he bmj |
BMJ
2017;358:j3119 | doi: 10.1136/bmj.j3119 1
RESEARCH
E ec o die and physical ac i i y based in e en ions
in p egnancy on ges a ional weigh gain and p egnancy
ou comes: me a-analysis o indi idual pa icipan da a om
andomised ials
The In e na ional Weigh Managemen in P egnancy (i-WIP) Collabo a i e G oup
ABSTRACT
Objec i e
To syn hesise he e idence on he o e all and
di e en ial e ec s o in e en ions based on die
and physical ac i i y du ing p egnancy, p ima ily on
ges a ional weigh gain and ma e nal and o sp ing
composi e ou comes, acco ding o women’s body mass
index, age, pa i y, e hnici y, and p e-exis ing medical
condi ion; and seconda ily on indi idual complica ions.
DESIGN
Sys ema ic e iew and me a-analysis o indi idual
pa icipan da a (IPD).
DATA SOURCES
Majo elec onic da abases om incep ion o Feb ua y
2017 wi hou language es ic ions.
ELIGIBILITY CRITERIA FOR SELECTING STUDIES
Randomised ials on die and physical ac i i y based
in e en ions in p egnancy.
DATA SYNTHESIS
S a is ical models accoun ed o clus e ing o
pa icipan s wi hin ials and he e ogenei y ac oss
ials leading o summa y mean di e ences o odds
a ios wi h 95% con idence in e als o he e ec s
o e all, and in subg oups (in e ac ions).
RESULTS
IPD we e ob ained om 36 andomised ials (12 526
women). Less weigh gain occu ed in he in e en ion
g oup han con ol g oup (mean di e ence −0.70 kg,
95% con idence in e al −0.92 o −0.48 kg, I2=14.1%;
33 s udies, 9320 women). Al hough summa y e ec
es ima es a ou ed he in e en ion, he educ ions
in ma e nal (odds a io 0.90, 95% con idence in e al
0.79 o 1.03, I2=26.7%; 24 s udies, 8852 women) and
o sp ing (0.94, 0.83 o 1.08, I2=0%; 18 s udies, 7981
women) composi e ou comes we e no s a is ically
signi ican . No e idence was ound o di e en ial
in e en ion e ec s ac oss subg oups, o ei he
ges a ional weigh gain o composi e ou comes.
The e was s ong e idence ha in e en ions educed
he odds o caesa ean sec ion (0.91, 0.83 o 0.99,
I2=0%; 32 s udies, 11 410 women), bu no o o he
indi idual complica ions in IPD me a-analysis. When
IPD we e supplemen ed wi h s udy le el da a om
s udies ha did no p o ide IPD, he o e all e ec
was simila , wi h s onge e idence o bene i o
ges a ional diabe es (0.76, 0.65 o 0.89, I2=36.8%;
59 s udies, 16 885 women).
CONCLUSION
Die and physical ac i i y based in e en ions du ing
p egnancy educe ges a ional weigh gain and lowe
he odds o caesa ean sec ion. The e is no e idence
ha e ec s di e ac oss subg oups o women.
In oduc ion
Hal o all women o childbea ing age wo ldwide
a e o e weigh o obese.1-3 Obesi y and excessi e
ges a ional weigh gain pu mo he and o sp ing
a isk, bo h in p egnancy and in la e li e.4-6 The
esul an cos s o he heal h se ice and socie y a e
conside able.7 8 Inc easingly, heal hca e o ganisa ions
and esea ch unding bodies p io i ise esea ch on
in e en ions and s a egies o educe ma e nal weigh
ela ed ad e se ou comes in p egnancy.9-12
Syn heses o s udy le el da a on e ec s o die and
physical ac i i y based in e en ions in p egnancy13
ha e shown an o e all bene i on limi ing ges a ional
weigh gain, bu he indings a ied o hei p o ec i e
e ec on ma e nal and o sp ing ou comes.13 14
Impo an ly, he subg oups o women who may bene i
he mos om such in e en ions a e no known.15 Fo
his, p ima y s udies do no ha e su icien powe ,16 17
and me a-analyses o s udy le el da a a e limi ed by he
absence o published de ails o subg oup e ec s,18 and
by po en ial ecological bias.19 These p oblems can be
add essed by e idence syn hesis using aw indi idual
le el da a om ele an s udies.20 21
We unde ook an indi idual pa icipan da a (IPD)
me a-analysis o assess he e ec s o die and physical
ac i i y based in e en ions, p ima ily on ges a ional
weigh gain and on ma e nal and o sp ing composi e
ou comes, in subg oups de ined by body mass index
(BMI), age, pa i y, e hnici y, and p e-exis ing medical
Co espondence o: K S Khan
k.s.kh[email p o ec ed]
Addi ional ma e ial is published
online only. To iew please isi
he jou nal online.
Ci e his as: BMJ 2017;358:j3119
h p://dx.doi.o g/10.1136/bmj.j3119
Accep ed: 15 June 2017
WHAT IS ALREADY KNOWN ON THIS TOPIC
Inc eased weigh gain in p egnancy is associa ed wi h ma e nal and e al
complica ions
In e en ions based on die o physical ac i i y o bo h in p egnancy minimise
ges a ional weigh gain
In e en ions based on die and physical ac i i y may ha e a po en ial ole in
p e en ing ad e se p egnancy ou comes
WHAT THIS STUDY ADDS
Die and physical ac i i y based in e en ions consis en ly educe ges a ional
weigh gain ac oss a ious subg oups o women ca ego ised by age, pa i y, body
mass index, e hnici y, and p e-exis ing medical condi ion
The educ ion in odds o ad e se ma e nal and o sp ing composi e ou comes
wi h die and physical ac i i y is no signi ican , and does no a y ac oss a ious
subg oups o women
In e en ions signi ican ly lowe he odds o caesa ean sec ion and ha e no
e ec on o sp ing ou comes
RESEARCH
2 doi: 10.1136/bmj.j3119 |
BMJ
2017;358:j3119 | he bmj
condi ion. Fu he mo e, we assessed he o e all e ec s,
and hose o indi idual in e en ions (die , physical
ac i i y, mixed), on c i ically impo an ma e nal and
o sp ing complica ions. In addi ion o using IPD, we
also assessed he impac o inco po a ing s udy le el
da a om o he s udies no p o iding IPD.
Me hods
The IPD me a-analysis was pe o med using a
p especi ied p o ocol (PROSPERO CRD42013003804)22
and was epo ed in line wi h ecommenda ions o he
P e e ed Repo ing I ems o Sys ema ic e iews and
Me a-Analysis o Indi idual Pa icipan Da a (PRISMA-
IPD).23
Li e a u e sea ch and s udy iden i ica ion
We sea ched he majo elec onic da abases Medline,
Embase, Coch ane Da abase o Sys ema ic Re iews,
Da abase o Abs ac s o Re iews o E ec s, Coch ane
Cen al Regis e o Con olled T ials, and Heal h
Technology Assessmen Da abase om Oc obe 2013
o Ma ch 2015 o upda e ou p e ious sea ch in his
opic o andomised ials on die and physical ac i i y
based in e en ions in p egnancy.13 The sea ch was
u he upda ed in Janua y 2016 and Feb ua y 2017 o
iden i y new s udies. We sea ched he in e ne by using
gene al sea ch engines, and con ac ed esea che s in
he special y o iden i y ele an ials. The e we e no
language es ic ions. Web appendix 1 p o ides de ails
o he sea ch s a egy.
Two independen esea che s (ER and NM, AAM, o
EM) selec ed s udies in a wo s age p ocess. In he i s
s age, po en ial ci a ions we e iden i ied. Nex , we did a
de ailed e alua ion o he ull manusc ip s o po en ial
pape s and selec ed a icles ha ul illed he eligibili y
c i e ia. We included andomised ials ha assessed he
e ec s o in e en ions based on die , physical ac i i y,
and mixed in e en ions in p egnancy, on ma e nal and
o sp ing ou comes. We classi ied complex in e en ions
on die and physical ac i i y, including hose wi h
beha iou al change componen s, as mixed in e en ions.
We excluded s udies ha only included women wi h
ges a ional diabe es a baseline, in ol ed animals,
epo ed only non-clinical ou comes, and we e published
be o e 1990. The p ima y ou comes we e ges a ional
weigh gain, a composi e o ma e nal ou comes, and
a composi e o o sp ing ou comes. The seconda y
ou comes we e indi idual ma e nal and o sp ing
complica ions. The componen s o he composi e
ou comes we e de e mined by a wo ound Delphi su ey
o esea che s in his special y, and we e conside ed o be
c i ically impo an o clinical p ac ice.24 The ma e nal
composi e ou come included ges a ional diabe es
melli us, hype ensi e diso de s o p egnancy, p e e m
deli e y, and caesa ean sec ion. The o sp ing composi e
ou come included s illbi h, small o ges a ional age
e us, la ge o ges a ional age e us, and admission o he
newbo n o a neona al in ensi e ca e uni .
We de ined ges a ional weigh gain as he di e ence
be ween ma e nal weigh a an ena al booking and he
las weigh measu ed be o e deli e y. We accep ed he
p ima y au ho s’ de ini ion and epo ing o ges a ional
diabe es melli us, p egnancy induced hype ension,
p e-eclampsia, caesa ean sec ion, s illbi h, and
admission o a neona al in ensi e ca e uni . We de ined
p e e m deli e y as bi h be o e 37 weeks o ges a ion,
and small o ges a ional age and la ge o ges a ional
age as babies wi h a bi h weigh below he 10 h and
a o o e he 90 h cen iles, espec i ely, adjus ed o
mo he ’s BMI, pa i y, and ges a ional age a deli e y.25
Es ablishmen o IPD collabo a i e ne wo k and
da abase—We es ablished he In e na ional Weigh
Managemen in P egnancy IPD Collabo a i e G oup
by con ac ing esea che s o eligible s udies.26 A
bespoke da abase was de eloped, and we eques ed
collabo a o s o ele an da a in any o ma . We sen
h ee eminde s when he e was no esponse.
Quali y assessmen o he included s udies
Two independen e iewe s assessed he quali y o he
andomised ials using a isk o bias ool o sequence
gene a ion, alloca ion concealmen , blinding, incomple e
ou come da a, selec i e ou come epo ing, and o he
po en ial sou ces o bias.27 We conside ed a s udy o
ha e a high isk o bias i i sco ed as such in a leas one
o he ollowing domains: andomisa ion, alloca ion
concealmen , blinding o ou come assessmen , o
incomple e ou come da a; all i ems should be sco ed as
low isk o a s udy o be classi ied as low isk o bias.
Da a ex ac ion and assessmen o IPD in eg i y
Two independen e iewe s (ER and NM) unde ook
da a ex ac ion a s udy le el o inclusion and exclusion
c i e ia, he cha ac e is ics o he in e en ion, and
he epo ed ou comes. We sough o ob ain IPD om
ele an s udies published un il July 2015, which was
he endpoin o IPD acquisi ion, o allow su icien ime
o da a cleaning, s anda disa ion, and amalgama ion
o da ase s. We also ex ac ed he published s udy le el
da a o all ele an s udies published un il Feb ua y
2017, including hose published beyond he indi idual
da a acquisi ion imeline, and hose o which IPD
we e no p o ided by s udy au ho s.
We ob ained IPD o indi idual ma e nal
cha ac e is ics ha we e de e mined a p io i, such as
BMI, age, pa i y, e hnici y, socioeconomic s a us, and
p e-exis ing medical condi ions. Con inuous a iables
we e kep con inuous, bu some we e also ca ego ised
when conside ed o be clinically use ul. These included
ca ego isa ions based on BMI (no mal 18.5-24.9 kg/m2,
o e weigh 25-29.9 kg/m2, obese ≥30 kg/m2) and age
(cu -o 20 yea s). Mo he ’s e hnici y was classi ied as
whi e o non-whi e. We used he mo he ’s educa ional
s a us o indica e socioeconomic s a us: low s a us i
he mo he did no comple e seconda y educa ion o A
le el, medium i she comple ed seconda y educa ion
(A le el equi alen ), and high i she comple ed any
u he highe educa ion. We de ined p e-exis ing
medical condi ions as diabe es melli us, ea ly onse o
ges a ional diabe es, o hype ension.
We conside ed pa icipan s o be adhe en o
he in e en ion based on he ollowing c i e ia:
RESEARCH
he bmj |
BMJ
2017;358:j3119 | doi: 10.1136/bmj.j3119 3
comple ion o a leas 70% o he in e en ion
p o ocol, da ase p o ided in o ma ion on adhe ence
in a yes o no o ma , o pa icipan was deemed o
be adhe en as pe he s udy c i e ia. We pe o med
ange and consis ency checks on all IPD and p oduced
summa y ables. The andomisa ion a io, baseline
cha ac e is ics, and me hod o analysis in he IPD
da ase we e compa ed wi h he published in o ma ion.
Any disc epancies, missing da a, ob ious e o s, and
inconsis encies be ween a iables o ou lying alues
we e que ied and ec i ied as necessa y wi h inpu
om he o iginal au ho s.
Da a syn hesis
To ob ain summa y es ima es (mean di e ence o
ges a ional weigh gain and odds a ios o bina y
ou comes) and 95% con idence in e als o he
in e en ion e ec s o each p ima y ou come we
unde ook a wo s age IPD me a-analysis.21 We
assessed he e ec s ac oss all in e en ions o e all
and o indi idual in e en ions. A wo s age IPD me a-
analysis was used o ob ain summa y es ima es o
he subg oup e ec s (in e ac ions) o in e es , which
compa ed di e en ial e ec s o in e en ions ac oss he
p ima y ou comes. Addi ionally we e alua ed whe he
he e a e any di e en ial e ec s o in e en ions o
indi idual complica ions, acco ding o BMI (no mal,
o e weigh , obese). All analyses we e designed o
p ese e he in en ion o ea p inciple.
The i s s age o he wo s age me a-analysis in ol ed
analysing he IPD in each ial sepa a ely, o accoun
o he clus e ing o pa icipan s wi hin ials, and o
ob ain he es ima es o in e es and hei a iances. Fo
he clus e andomised ials, we included a andom
in e cep o a uni o andomisa ion o accoun o
his u he clus e ing. Fo he ou come o ges a ional
weigh gain, we used analysis o co a iance in each
ial o eg ess he inal weigh alue agains he
in e en ion while adjus ing o baseline weigh and
cen es in clus e andomised ials. Fo ma e nal and
o sp ing ou comes, we used a logis ic eg ession model
o each ial sepa a ely, wi h he in e en ion as a
co a ia e. We excluded women wi h con i med glucose
in ole ance o a hype ensi e diso de a baseline,
as de ined by he p ima y au ho s, in he analysis o
composi e ad e se p egnancy ou comes. To assess
po en ial in e en ion e ec modi ie s, we ex ended
he a o emen ioned models o include in e ac ion
e ms be ween pa icipan le el co a ia es and he
in e en ion (ie, ea men -co a ia e in e ac ion e ms).
In he second s age, we pooled he de i ed e ec
es ima es (ie, ea men e ec s o ea men -co a ia e
in e ac ions) ac oss ials using a andom e ec s
model i ed using es ic ed maximum likelihood. The
andom e ec s app oach allowed us o accoun o
unexplained in e s udy he e ogenei y in e ec s ac oss
s udies. This p oduced summa y es ima es and 95%
con idence in e als o he in e en ion e ec s and he
in e ac ions (subg oup e ec s). The Ha ung-Knapp
co ec ion was applied when subsequen ly de i ing
95% con idence in e als o he ue mean e ec ,
o help accoun o he unce ain y o he es ima e o
in e s udy he e ogenei y.28 29
We included s udies ha did no con ibu e IPD, by
inco po a ing hei ex ac ed s udy le el da a wi hin
he second s age o he IPD me a-analysis amewo k,
o ob ain summa y es ima es o in e en ion e ec s
ha combined IPD and non-IPD s udies. Sensi i i y
analyses we e also pe o med by excluding s udies
wi h high isk o bias, analysing he p ima y ou comes
sepa a ely o each in e en ion ype (die , physical
ac i i y, and mixed), excluding pa icipan s no
adhe en o he in e en ion, by analysing change in
BMI ins ead o weigh gain, and excluding ma e nal
weigh gain es ima es om p egnancies ha ended
be o e 37 comple ed weeks o ges a ion o a oid
sys ema ic di e ences.
He e ogenei y was summa ised using he I2
s a is ic, he es ima ed in e s udy a iance (τ2),30 and
app oxima e 95% p edic ion in e als, which indica e
he po en ial in e en ion (o in e ac ion) e ec in a
new popula ion simila o hose included in he me a-
analysis.31
Small s udy e ec s (po en ial publica ion bias) we e
in es iga ed by using con ou enhanced unnel plo s
alongside isual examina ion and s a is ical es s o
asymme y (Egge ’s es o con inuous ou comes o
Pe e ’s es o bina y ou comes).32 We assessed o IPD
a ailabili y bias by compa ing he summa y esul s
when including non-IPD s udies wi h hose om IPD
s udies.33 Fu he mo e, we compa ed he symme y
o unnel plo s be o e and a e inclusion o non-IPD
s udies. All me a-analyses we e unde aken using S a a
so wa e e sion 12.1 (S a aCo p, College S a ion, TX,
USA), and s a is ical signi icance was conside ed a he
5% le el.
Pa ien in ol emen
No pa ien s we e in ol ed in se ing he esea ch
ques ion o he ou come measu es, no we e hey
in ol ed in de eloping plans o ec ui men , design, o
implemen a ion o he s udy. A pa ien ep esen a i e
p o ided an inpu o he in e p e a ion and w i ing up
o esul s. The e a e no plans o dissemina e he esul s
o he esea ch o s udy pa icipan s o he ele an
pa ien communi y. I was no e alua ed whe he
he s udies included in he e iew had any pa ien
in ol emen .
Resul s
S udy selec ion
We iden i ied 58 ials published up o June 2015,
o which 36 s udies (62%) p o ided indi idual
pa icipan da a (IPD),16 17 34-66 ha accoun ed o
da a om 80% o he pa icipan s (12 526/15 541); 22
s udies (3015 women) did no p o ide IPD ( ig 1).67-88
A u he 45 ials (9945 women)89-133 we e iden i ied
a e he IPD acquisi ion imeline un il Feb ua y 2017.
Cha ac e is ics o included s udies and pa icipan s
IPD we e a ailable om 36 ials in 16 coun ies.
Twen y wo s udies17 34 36-39 41 42 47 48 51-53 56-63 67 we e
RESEARCH
4 doi: 10.1136/bmj.j3119 |
BMJ
2017;358:j3119 | he bmj
om Eu ope, ou each om No h Ame ica,4454
65 66 Aus alia,16 43 45 50 and B azil,35 49 55 64 and
one s udy each om Egyp 40 and I an.46 Twen y
h ee IPD s udies included women o any body
mass index (BMI),
34-38 42 44-48 52 54-56 58-61 64-67 se en
included only obese women,1739-41 50 62 63 and six
included obese and o e weigh women.16 43 49 51 53 57
The in e en ions included hose mainly based on
die ( ou IPD s udies)47 61 62 64 o physical ac i i y
(16 IPD s udies),35-37 42 46 49-52 55 58 59 65 66 69 and
hose based on a mixed app oach o die , physical
ac i i y, o beha iou modi ying echniques, o all
h ee oge he (15 IPD s udies).16 17 34 39-41 43-45 48
53 54 56 60 63 One s udy had a h ee a m design wi h
in e en ion a ms being physical ac i i y only and a
mixed app oach.57 The web appendix p o ides he
cha ac e is ics o all IPD s udies, and also hose ha
did no con ibu e IPD.
Eligible s udies iden i ied beyond da a
acquisi ion imeline (n=45; 9945 women)
S udies o which IPD we e sough (n=58)
S udies o which IPD da a we e no
a ailable (n=67; 12 960 women)
Ges a ional weigh gain (n=48; 8210 women)
Ma e nal ou comes
Ges a ional diabe es (n=32; 8033 women)
Hype ensi e diso de o p egnancy (n=23; 5231 women)
P e e m bi h (n=17; 2663 women)
Caesa ean sec ion (n=34; 6631 women)
O sp ing ou comes
S illbi h (n=2; 815 women)
Small o ges a ional age (n=11; 1271 women)
La ge o ges a ional age (n=11; 1301 women)
Admission o NICU (n=5; 1358 women)
S udies ha p o ided IPD (n=36; 12 526 women)
Ci a ions om p e ious sys ema ic e iew
(incep ion o Jan 2012) and o he sou ces† (n=105)
Ci a ions om elec onic da abases sea ch
om Jan 2012 o Feb 2017* (n=11 815)
Reco ds a ailable a e duplica es emo ed (n=7038)
Full ex s udies assessed o eligibili y (n=218)
Eligible s udies (n=103)
S udies wi h IPD and wi hou lPD a ailabili y
Ma e nal ou comes: ges a ional weigh gain (n=81; 17 530 women), ges a ional diabe es (n=59; 16 1885 women),
hype ensi e disease (n=45; 14 849 women), p e e m bi h (n=49; 14 339 women), caesa ean sec ion (n=66; 18 041 women)
O sp ing ou comes: sS illbi h (n=4; 4534 women), small o ges a ional age (n=44; 12 937 women),
la ge o ges a ionaI age (n=45; 13 348 women), admission o NICU (n=21; 9498 women)
Ci a ions excluded (n=6820)
Excluded (n=115):
Published be o e 1990 (n=4)
Pilo ial inco po a ed in o main ial (n=2)
P o ocol (ongoing ec ui men ) (n=37)
I ele an s udy objec i e o in e en ion (n=15)
Ac i e compa ison (n=28)
No obs e ic ou comes (n=11)
W ong s udy popula ion (n=14)
Full ex o abs ac no a ailable (n=4)
S udies ha did no p o ide IPD (n=22):
Con lic o in e es (n=2; 610 women )
Lack o ime (n=2; 286 women)
Da a sha ing issue (n=1; 132 women)
Da a loss (n=2; 421 women)
Con ac loss (n=4; 531 women)
No esponse (n=11; 1035 women)
Ges a ional weigh gain (n=33; 9320 women)
Ma e nal composi e (n=24; 8852 women)
Ges a ional diabe es (n=27; 9427 women)
Hype ensi e diso de o p egnancy (n=22; 9618 women)
P e e m bi h (n=32; 11 676 women)
Caesa ean sec ion (n=32; 11 410 women)
O sp ing composi e (n=18; 7981 women)
S illbi h (n=2; 3719 women)
Small o ges a ional age (n=33; 11 666 women)
La ge o ges a ional age (n=34; 12 047 women)
Admission o NICU (n=16; 8140 women)
NICU=neona al in ensi e ca e uni
*Da abase sea ch was upda ed in Oc obe 2013 (9359 eco ds), Ma ch 2015 (3551 eco ds), Janua y 2016 (1373 eco ds), and Feb ua y 2017 (1547 eco ds)
†O he sou ces: e e ence sea ch, pe sonal communica ion, and Google sea ch
Fig1 | Iden i ica ion and selec ion o s udies in indi idual pa icipan da a (IPD) me a-analysis o die and physical
ac i i y based in e en ions on p egnancy ou comes a e ges a ional weigh gain
RESEARCH
he bmj |
BMJ
2017;358:j3119 | doi: 10.1136/bmj.j3119 5
Mo e han 80% o women in he IPD me a-analyses
we e o whi e o igin, and a leas hal we e classi ied
as o high socioeconomic s a us. A ound 45% o
women we e nullipa ous, 40% we e obese, and a
simila p opo ion was classi ied as ha ing seden a y
s a us wi h no exe cise a baseline ( able 1). IPD
we e a ailable o assess he e ec s o in e en ions
on ges a ional weigh gain (33 s udies, 9320
women), ma e nal composi e ou comes (24 s udies,
8852 women), and o sp ing composi e ou comes
(18 s udies, 7981 women). The la ges IPD we e
a ailable o he ou come o la ge o ges a ional
age e us (34 s udies, 12 047 women), ollowed by
p e e m deli e y (32 s udies, 11 676 women), small
o ges a ional age e us (33 s udies, 11 666 women),
any caesa ean sec ion (32 s udies, 11 410 women),
hype ensi e diso de s o p egnancy (22 s udies,
9618 women), and ges a ional diabe es (27 s udies,
9427 women). We did no ha e access o IPD o
51% o all eligible women (12 960/25 486) om 67
s udies ( ig 1).
Quali y o included s udies
O e all, ials had a low isk o bias in andom
sequence gene a ion (71%, 73/103). Mo e han 90%
(34/36) o s udies ha con ibu ed o he IPD we e
assessed as low isk o bias in his domain compa ed
wi h 58% (28/67) o he non-IPD s udies. Two IPD
s udies (2/36) and one non-IPD s udy (3/67) we e
conside ed high isk o alloca ion concealmen .
Blinding o ou come assessmen was app op ia e
in 44% (16/36) o IPD and 33% (22/67) o non-IPD
s udies ( ig 2). Fewe IPD s udies (5/36) we e assessed
as high isk o bias o incomple e ou come da a han
non-IPD s udies (15/67). Figu e 2 shows he summa y
o he isk o bias es ima es o all eligible s udies
and hose ha did and did no con ibu e o IPD. We
did no encoun e any issues ha we we e no able
o cla i y wi h he IPD con ibu o du ing he IPD
in eg i y check.
Table1 | Baseline cha ac e is ics o women included in s udies ha con ibu ed o he me a-analysis o indi idual
pa icipan da a on die and physical ac i i y based in e en ions in p egnancy. Values a e numbe s (pe cen ages*)
unless s a ed o he wise
Cha ac e is ics No o s udies (No o women) In e en ion Con ol
Mean (SD) age (yea s) 35 (12 006) 30.0 (5.1) 30.1 (5.2)
Weigh (body mass index): 34 (12 031)
No mal (18.5-24.9 kg/m2)1974 (31.7) 1842 (31.8)
O e weigh (25-29.9 kg/m2)1578 (25.3) 1523 (26.3)
Obese (≥30 kg/m2)2680 (43.0) 2434 (42.0)
Race/e hnici y: 27 (10 020)
Whi e (including Russians and Aus alians) 4562 (88.0) 4217 (87.2)
Asian 157 (3.0) 156 (3.2)
Black 292 (5.6) 292 (6.0)
Cen al and Sou h Ame ican 67 (1.3) 64 (1.3)
Middle Eas e n (including I anian and Tu kish) 37 (0.7) 37 (0.8)
O he 71 (1.4) 68 (1.4)
Educa ional s a us o mo he †: 29 (8914)
Low 722 (15.6) 724 (16.9)
Medium 1372 (29.6) 1292 (30.2)
High 2536 (54.8) 2268 (52.9)
Smoke 29 (10 958) 875 (15.4) 865 (16.4)
Pa i y: 33 (11 805)
0 3027 (49.5) 2692 (47.3)
1 2136 (34.9) 2083 (36.6)
2 647 (10.6) 634 (11.1)
3 179 (2.9) 165 (2.9)
≥4 129 (2.1) 113 (2)
No exe cise o seden a y 27 (7583) 1761 (44.6) 1731 (47.6)
P e-exis ing diabe es melli us 25 (9589) 6 (0.1) 9 (0.2)
P e-exis ing hype ension 23 (5494) 73 (2.5) 54 (2.1)
*P opo ion ou o obse a ions in con ol o in e en ion a ms, espec i ely.
†Low=no comple ed seconda y educa ion o A le el; medium=comple ed seconda y educa ion (A le el equi alen ); high=any u he o highe educa ion.
No o s udies assessed o isk o bias
All eligible s udies
IPD
Non-IPD
All eligible s udies
IPD
Non-IPD
All eligible s udies
IPD
Non-IPD
All eligible s udies
IPD
Non-IPD
All eligible s udies
IPD
Non-IPD
All eligible s udies
IPD
Non-IPD
0
20
40
60
80
100
Random
sequence
gene a ion
High Unclea Low
4
26
73
2
34
4
24
39
49
23
26
60
17
43
38 16
22
71
28
42
5
49
3
11
2
38
43
19
24
5
49
14
6
2
43
20
12
5
3
15
10
73 23
50
20
11
7
6
5
12
Alloca ion
concealmen
Blinding o
pa icipan s
and s a
Blinding o
ou come
assessmen
Incomple e
ou come
da a
Selec ing
epo ing
Fig2 | Assessmen o isk o bias in all eligible s udies (n=103), s udies wi h indi idual
pa icipan da a (IPD) (n=36), and s udies wi hou access o IPD (n=67)

RESEARCH
6 doi: 10.1136/bmj.j3119 |
BMJ
2017;358:j3119 | he bmj
E ec s o in e en ions on p egnancy ou comes
Ges a ional weigh gain
Based on IPD me a-analysis (33 s udies, 9320 women),
die and physical ac i i y based in e en ions esul ed
in signi ican ly less ges a ional weigh gain compa ed
wi h con ol (summa y mean di e ence −0.70 kg, 95%
con idence in e al −0.92 o −0.48 kg, I2=14.1%),
a e adjus ing o baseline weigh and clus e ing. The
app oxima e 95% p edic ion in e al o he in e en ion
e ec in a new se ing was −1.24 o −0.16 kg ( able 2).
Di e en ial e ec s in subg oups
No s ong e idence was ound o a ea men -co a ia e
in e ac ion o baseline BMI when ea ed as a
con inuous co a ia e (−0.02 kg change in in e en ion
e ec pe one uni inc ease in BMI, 95% con idence
in e al −0.08 o 0.04 kg), o when compa ed as
o e weigh e sus no mal (−0.11 kg, −0.77 o 0.55 kg),
obese e sus no mal (0.06 kg, −0.90 o 1.01 kg), and
obese e sus o e weigh (−0.09 kg, −1.05 o 0.86 kg).
We also did no obse e e idence o a subg oup e ec
o age (−0.03 kg pe one yea inc ease in age, 95%
con idence in e al −0.08 o 0.02 kg), pa i y (0.10 kg
change in e ec o mul ipa i y e sus nullipa i y, 95%
con idence in e al −0.39 o 0.60 kg), e hnici y (0.05
kg change in e ec o non-whi e e sus whi e, 95%
con idence in e al −1.27 o 1.37 kg), and unde lying
medical condi ion (1.51 kg change in e ec o
women wi h a leas one condi ion e sus none, 95%
con idence in e al −2.01 o 5.02 kg). The indings
we e consis en when con inuous co a ia es we e
analysed as ca ego ical measu es based on clinically
ele an cu poin s ( able 3).
Sensi i i y analyses
The educ ion in ges a ional weigh gain owing o he
in e en ion was consis en ly obse ed when he analysis
was es ic ed o s udies wi h low isk o bias (−0.67 kg,
95% con idence in e al −0.95 o −0.38 kg; 15 s udies,
5585 women), women adhe en o he in e en ion
(−0.76 kg, −1.00 o −0.52 kg; 33 s udies, 8565 women),
women ollowed up un il mo e han 37 weeks’ ges a ion
(−0.91 kg, −1.17 o −0.66 kg; 28 s udies, 5324 women),
and o BMI ins ead o ma e nal weigh as an ou come
(−0.30 kg/m2, −0.39 o −0.21 kg/m2; 31 s udies, 9238
women).
Table2 | E ec s o die and physical ac i i y based in e en ions on ges a ional weigh gain summa ised using indi idual pa icipan da a (IPD)
alone, and by supplemen ing IPD wi h s udy le el da a om s udies ha did no con ibu e IPD. Values a e means (s anda d de ia ions) unless s a ed
o he wise
Ou comes
No o s udies (No o women) In e en ion Con ol Mean di e ence (95% CI) I2 (%)
IPD IPD and non-IPD IPD
IPD and
non-IPD IPD
IPD and
non-IPD IPD IPD and non-IPD IPD
IPD and
non-IPD
O e all 33 (9320) 81 (17 530) 10.1 (5.4) 10.6* 10.8 (5.4) 11.5* −0.70 (−0.92 o −0.48) −1.10 (−1.46 o −0.74) 14.1 73.8
Die 4 (1168) 12 (2017) 10.2 (4.4) 9.2* 11.0 (4.8) 11.7* −0.72 (−1.48 o 0.04) −2.84 (−4.77 o −0.91) 0.0 92.3
Physical ac i i y 15 (2915) 37 (7355) 9.8 (4.4) 11.3* 10.8 (4.8) 11.9* −0.73 (−1.11 o −0.34) −0.72 (−1.04 o −0.41) 0.0 45.4
Mixed app oach 15 (5369) 35 (8448) 10.2 (6.0) 10.3* 10.6 (5.9) 11.0* −0.71 (−1.10 o −0.31) −1.00 (−1.39 o −0.61) 34.9 54.6
*Recalcula ion using De Simonian-Lai d.
Table3 | Di e en ial e ec s o die and physical ac i i y based in e en ions on ges a ional weigh gain in subg oups o
p egnan women
Ma e nal cha ac e is ics
No o s udies
(No o women)
Mean di e ence* kg
(95% CI)
T ea men co a ia e in e ac ion
Coe icien ; 95% CI (95% PI) I2 (%)
Baseline body mass index:
No mal 21 (3376) −0.77 (−1.15 o −0.39) −0.02; −0.08 o 0.04 (−0.21 o 0.17)† 39.8
O e weigh 28 (2574) −0.75 (−1.22 o −0.27)
Obese 31 (3335) −0.85 (−1.41 o −0.29)
Pa i y:
Nullipa ous 27 (4513) −0.80 (−1.17 o −0.43) 0.10; −0.39 o 0.60 (−0.83 o 1.04)‡ 4.8
Mul ipa ous 27 (4548) −0.62 (−0.88 o −0.37)
E hnici y:
Whi e 21 (6814) −0.74 (−1.07 o −0.42) 0.05; −1.27 o 1.37 (−1.28 o 1.39)§ 26.1
Non-whi e 15 (621) −0.42 (−1.12 o 0.28)
Age (yea s):
≥20 32 (9045) −0.72 (−0.95 o −0.50) −0.03; −0.08 o 0.02 (−0.14 o 0.09)¶ 25.9
<20 13 (232) 0.05 (−1.34 o 1.44)
P e-exis ing medical condi ions**:
None 18 (4335) −0.62 (−0.90 o −0.34) 1.51; −2.01 o 5.02 (−4.13 o 7.15)†† 28.4
≥1 6 (128) 0.40 (−1.92 o 2.71)
PI=p edic ion in e al.
*Model accoun ed o baseline weigh and clus e ing e ec .
†Pe uni o body mass index.
‡Mul ipa ous e sus nullipa ous.
§Non-whi e e sus whi e.
¶Pe yea o age.
**Diabe es melli us o hype ension.
†† ≥1 medical condi ion e sus none.
RESEARCH
he bmj |
BMJ
2017;358:j3119 | doi: 10.1136/bmj.j3119 7
Addi ion o s udies ha did no con ibu e IPD
In me a-analysis unde aken by supplemen ing he
IPD wi h s udy le el da a om s udies (48 s udies,
8210 women) ha did no con ibu e IPD, we obse ed
a la ge bene icial in e en ion e ec o weigh gain
(summa y mean di e ence −1.1 kg; 95% con idence
in e al −1.46 o −0.74 kg; 81 s udies, 17 530
women). The bene i was also consis en ly obse ed
o indi idual in e en ions based on die , physical
ac i i y, o mixed app oach ( able 2).
Ma e nal and o sp ing composi e ou comes
In he IPD me a-analyses, he summa y es ima es
a ou ed he in e en ion g oup o educ ion in odds
o ma e nal (odds a io 0.90, 95% con idence in e al
0.79 o 1.03, I2=26.7%; 24 s udies, 8851 women) and
o sp ing composi e ou comes (0.94, 0.83 o 1.08,
I2=0%; 18 s udies, 7981 women), bu hese we e no
s a is ically signi ican ( able 4).
Di e en ial e ec s ac oss subg oups
We obse ed no s ong e idence o di e en ial
subg oup e ec s o ma e nal composi e ou come
acco ding o ei he baseline BMI ( ea men -co a ia e
in e ac ion 1.00, 95% con idence in e al 0.98 o
1.02), age (1.01, 0.99 o 1.03), pa i y (1.03, 0.75 o
1.39), e hnici y (0.93, 0.63 o 1.37), and unde lying
medical condi ion (1.44, 0.15 o 13.74) ( able 5).
A simila lack o di e en ial e ec was obse ed
o o sp ing composi e ou come in mo he s g ouped
acco ding o baseline BMI (in e ac ion 0.98, 95%
con idence in e al 0.95 o 1.00), age (1.01, 0.98 o
1.04), pa i y (0.94, 0.64 o 1.37), e hnici y (1.12, 0.75
o 1.68), and unde lying medical condi ion (0.58,
0.03 o 9.81) ( able 4). The indings did no change
o ma e nal and o sp ing composi e ou comes when
BMI and age we e analysed as con inuous ins ead o
ca ego ical a iables.
Indi idual ma e nal ou comes
O e all, in he IPD me a-analysis we obse ed a
signi ican educ ion in caesa ean sec ion (odds
a io 0.91, 95% con idence in e al 0.83 o 0.99,
I2=0%; 32 s udies, 11 410 women) o in e en ions
compa ed wi h ou ine ca e. The educ ion in o he
indi idual ou comes such as ges a ional diabe es
(0.89, 0.72 o 1.10, I2=23.8%; 27 s udies, 9427
women), hype ensi e diso de s o p egnancy (0.95,
0.78 o 1.16, I2=24.2%; 22 s udies, 9618 women),
and p e e m deli e y (0.94, 0.78 o 1.13, I2=17.3%;
32 s udies, 11 676 women) we e no s a is ically
signi ican in IPD me a-analyses ( able 5). We did no
obse e any di e en ial e ec acco ding o baseline
BMI ca ego y (no mal, o e weigh , obese) o any o
he indi idual ma e nal ou comes (see web appendix
3). The indings we e consis en when s udy le el da a
om non-IPD s udies we e me a-analysed wi h IPD,
bu wi h a s onge e idence o bene i o ges a ional
diabe es. The educ ion in ges a ional diabe es (0.76,
0.65 o 0.89, 36.8%; 59 s udies, 16 885 women)
became signi ican ( able 5).
Among indi idual in e en ions, hose based mainly
on physical ac i i y showed a educ ion in ges a ional
diabe es in bo h IPD (odds a io 0.67, 95% con idence
in e al 0.46 o 0.99, I2=0%; 10 s udies, 2700 women)
and in combined (IPD and non-IPD) me a-analyses
(0.66, 0.53 o 0.83, I2=0%; 27 s udies, 6755 women).
While he summa y es ima es o physical ac i i y
based in e en ions a ou ed caesa ean sec ion (0.82,
0.67 o 1.01, I2=0%; 13 s udies, 3046 women) and
hype ensi e diso de s o p egnancy (0.74, 0.42 o
1.33, I2=6.0%; 7 s udies, 2565 women) in IPD me a-
analyses, he addi ion o non-IPD s udies esul ed in
s onge e idence o bene i o hese complica ions,
wi h educ ion in he espec i e odds by 17% (0.83,
0.73 o 0.95, I2=0%; 32 s udies, 6587 women) and
32% (0.68, 0.49 o 0.93, I2=0%; 20 s udies, 5125
women).
A s ong e ec was obse ed o p e e m bi h wi h
die based in e en ions in bo h IPD (odds a io 0.28,
95% con idence in e al 0.08 o 0.96, I2=0%; 4 s udies,
1344 women) and combined analyses (0.32, 0.14 o
0.70, I2=0%; 7 s udies, 1696 women), bu he o e all
sample sizes we e ela i ely small ( able 5). The e was
no e idence o bene i wi h mixed in e en ions o any
ma e nal ou comes.
Indi idual o sp ing ou comes
No s ong e idence was ound ha in e en ions
had an e ec on indi idual o sp ing ou comes
such as s illbi h (odds a io 0.81, 95% con idence
in e al <0.001 o 256.69, I2=0%; 2 s udies, 3719
women), small o ges a ional age e us (1.06, 0.94
o 1.20, I2=0%; 33 s udies, 11 666 women), la ge o
ges a ional age e us (0.90, 0.76 o 1.07, I2=38.0%;
34 s udies, 12 047 women), and admission o a
neona al in ensi e ca e uni (1.01, 0.84 o 1.23,
I2=0%; 16 s udies, 8140 women) based on he IPD
me a-analyses. The signi icance o he indings did
no change when non-IPD s udies we e added o
he IPD me a-analyses ( able 5). The numbe s o
eligible pa icipan s o whom da a we e ob ained,
e ec es ima es, and con idence in e als o all
abo e analyses a e a ailable om he s udy au ho s
on eques . The e was no di e en ial e ec o any
indi idual o sp ing ou come acco ding o he BMI
ca ego y (see web appendix 3).
Small s udy e ec s
We ound isual and s a is ical e idence (Egge ’s es
P=0.04) o small s udy e ec s in he con ou enhanced
unnel plo s o he IPD me a-analysis o he o e all
e ec on ges a ional weigh gain. The asymme y o
he plo was no imp o ed by he addi ion o s udy
le el da a om non-IPD s udies o he me a-analysis.
When s udies wi h high isk o bias we e excluded
om he analysis, he symme y o he unnel plo
imp o ed (Egge ’s es P=0.61). We ound signi ican
e idence o small s udy e ec s o he ma e nal
composi e ou come (Pe e ’s es P=0.04), bu no o
he o sp ing composi e ou come (P=0.85) (see web
appendix 4).
RESEARCH
8 doi: 10.1136/bmj.j3119 |
BMJ
2017;358:j3119 | he bmj
Discussion
Ou la ge, collabo a i e indi idual pa icipan da a
(IPD) me a-analysis con i ms ha die and physical
ac i i y based in e en ions in p egnancy educe
ges a ional weigh gain. This bene icial e ec was
consis en ly obse ed i espec i e o ma e nal
body mass index (BMI), age, pa i y, e hnici y, o
p e-exis ing medical condi ion; and emained
when s udies a high isk o bias we e excluded.
The indings a e gene alisable, wi h he 95%
Table4 | E ec s o die and physical ac i i y based in e en ions on p egnancy ou comes summa ised using indi idual pa icipan da a (IPD) alone,
and by supplemen ing IPD wi h s udy le el da a om s udies ha did no con ibu e IPD
Ou comes
No o s udies
(No o women)
In e en ion:
e en /No e en Con ol: e en /No e en Odds a io (95% CI) I2 (%)
IPD
IPD and
non-IPD IPD
IPD and
non-IPD IPD
IPD and
non-IPD IPD
IPD and
non-IPD IPD
IPD and
non-IPD
Ma e nal
Composi e ou come:
O e all 24 (8851) NA 1896/2728 NA 1837/2390 NA 0.90 (0.79 o 1.03) NA 26.7 NA
Die 3 (397) NA 42/137 NA 84/134 NA 0.60 (0.20 o 1.75) NA 0.0 NA
Physical ac i i y 9 (2311) NA 346/850 NA 367/748 NA 0.81 (0.61 o 1.09) NA 10.8 NA
Mixed app oach 13 (6259) NA 1508/1742 NA 1438/3009 NA 0.97 (0.84 o 1.12) NA 34.9 NA
Ges a ional diabe es:
O e all 27 (9427) 59 (16 885) 584/4333 974/7764 571/3939 1046/7101 0.89 (0.72 o 1.10) 0.76 (0.65 o 0.89) 23.8 36.8
Die 4 (490) 8 (1106) 13/208 57/476 19/250 75/498 1.03 (0.30 o 3.61) 0.79 (0.37 o 1.69) 0.0 0.0
Physical ac i i y 10 (2700) 27 (6755) 90/1300 240/3153 121/1189 347/3015 0.67 (0.46 o 0.99) 0.66 (0.53 o 0.83) 0.0 0.0
Mixed app oach 14 (6355) 27 (9342) 481/2825 677/4135 441/2608 672/3858 1.02 (0.79 o 1.32) 0.88 (0.72 o 1.07) 35.2 10.8
Hype ensi e
diso de s o
p egnancy:
O e all 22 (9618) 45 (14 849) 432/4586 559/7130 423/4177 592/6568 0.95 (0.78 o 1.16) 0.85 (0.71 o 1.00) 24.2 21.5
Die 3 (397) 5 (729) 18/161 23/322 39/179 49/335 0.59 (0.07 o 4.65) 0.57 (0.18 o 1.79) 35.8 38.0
Physical ac i i y 7 (2565) 20 (5125) 55/1242 106/2513 73/1195 147/2359 0.74 (0.42 o 1.33) 0.68 (0.49 o 0.93) 6.0 0.0
Mixed app oach 13 (6797) 21 (9136) 359/3183 430/4295 322/2933 407/4004 1.05 (0.86 o 1.28) 1.01 (0.87 o 1.17)* 19.4 16.3
P e e m bi h:
O e all 32 (11 676) 49 (14 339) 332/5713 414/6971 345/5286 443/6511 0.94 (0.78 o 1.13) 0.92 (0.79 o 1.08) 17.3 8.7
Die 4 (1344) 7 (1696) 9/647 13/819 35/653 45/819 0.28 (0.08 o 0.96) 0.32 (0.14 o 0.70) 0.0 0.0
Physical ac i i y 13 (3249) 23 (5149) 95/1541 160/2431 73/1540 148/2410 1.29 (0.90 o 1.85) 1.09 (0.84 o 1.41) 0.0 0.0
Mixed app oach 16 (7219) 20 (7630) 228/3525 241/3721 243/3223 256/3412 0.91 (0.73 o 1.12) 0.92 (0.75 o 1.12) 0.0 32.3
Caesa ean sec ion:
O e all 32 (11 410) 66 (18 041) 1525/4385 2373/6860 1506/3994 2440/6368 0.91 (0.83 o 0.99) 0.89 (0.83 o 0.96) 0.0 16.2
Die 4 (1340) 7 (1732) 117/535 238/610 149/539 264/620 0.78 (0.50 o 1.22) 0.88 (0.65 o 1.17) 0.0 0.0
Physical ac i i y 13 (3046) 32 (6587) 306/1230 648/2646 349/1161 746/2547 0.82 (0.67 o 1.01) 0.83 (0.73 o 0.95) 0.0 0.0
Mixed app oach 16 (7160) 28 (9858) 1102/2620 1487/3604 1059/2379 1481/3286 0.95 (0.84 o 1.08) 0.92 (0.80 o 1.06) 17.6 21.9
O sp ing
Composi e ou come:
O e all 18 (7981) NA 1007/3172 NA 951/2851 NA 0.94 (0.83 o 1.08) NA 0.0 NA
Die 2 (346) NA 34/132 NA 48/132 NA 0.71 (0.03 o 18.23) NA 0.0 NA
Physical ac i i y 5 (1274) NA 138/495 NA 143/498 NA 0.99 (0.67 o 1.46) NA 0.0 NA
Mixed app oach 12 (6494) NA 835/2545 NA 797/2317 NA 0.95 (0.81 o 1.11) NA 4.7 NA
S illbi h†:
O e all 2 (3719) 4 (4534) 9/1858 12/2261 11/1841 14/2247 0.81 (<0.01 o 256.69) 0.85 (0.24 o 3.02) 0.0 0.0
Small o ges a ional
age:
O e all 33 (11 666) 44 (12 937) 709/5324 773/6018 632/5001 685/5461 1.06 (0.94 o 1.20) 1.05 (0.94 o 1.18) 0.0 0.0
Die 4 (1337) 6 (1628) 41/610 56/746 47/639 55/771 0.92 (0.45 o 1.88) 1.05 (0.62 o 1.77) 0.0 0.0
Physical ac i i y 14 (3272) 21 (3955) 243/1402 274/1740 232/1395 271/1670 1.05 (0.84 o 1.34) 1.01 (0.83 o 1.24) 12.3 51.7
Mixed app oach 16 (7193) 20 (7670) 425/3312 443/3532 370/3086 386/3309 1.08 (0.92 o 1.28) 1.08 (0.93 o 1.27) 0.0 0.0
La ge o ges a ional
age:
O e all 34 (12 047) 45 (13 348) 744/5492 820/6185 759/5052 833/5510 0.90 (0.76 o 1.07) 0.86 (0.71 o 1.04) 38.0 41.0
Die 4 (1408) 6 (1699) 155/529 172/663 176/548 203/661 0.91 (0.60 o 1.37) 0.82 (0.54 o 1.22) 0.0 0.0
Physical ac i i y 15 (3330) 21 (3930) 121/1557 159/1842 124/1528 161/1768 0.96 (0.59 o 1.54) 0.96 (0.67 o 1.37) 34.3 6.9
Mixed app oach 16 (7450) 21 (8040) 468/3406 489/3680 481/3095 523/3348 0.89 (0.67 o 1.17) 0.83 (0.62 o 1.10) 51.0 4.3
Admission o neona al
in ensi e ca e uni :
O e all 16 (8140) 21 (9498) 302/3973 406/4543 279/3586 400/4149 1.01 (0.84 o 1.23) 0.97 (0.82 o 1.14) 0.0 0.0
Die 1 (289) 2 (389) 3/137 11/179 13/136 29/170 NA‡ 0.33 (<0.01 o 47.97) NA 0.0
Physical ac i i y 3 (1166) 4 (1240) 31/552 34/586 40/543 43/577 0.77 (0.21 o 2.81) 0.79 (0.35 o 1.78) 20.8 0.0
Mixed app oach 13 (6818) 15 (7771) 268/3284 360/3626 230/3036 332/3453 1.10 (0.89 o 1.35) 1.05 (0.88 o 1.25) 0.0 0.0
*Recalcula ion using De Simonian-Lai d.
†All da a come om s udies wi h mixed app oach in e en ions.
‡No possible o es ima e s anda d de ia ions.
RESEARCH
he bmj |
BMJ
2017;358:j3119 | doi: 10.1136/bmj.j3119 9
p edic ion in e al sugges ing a bene icial e ec
on ges a ional weigh gain when he in e en ion
is applied in a new popula ion o se ing. The e is
no s ong e idence ha in e en ions educe he
isk o ma e nal and o sp ing composi e ou comes,
wi h no a ia ion in e ec obse ed ac oss he
subg oups.
Fo indi idual ou comes, in e en ions educe
caesa ean sec ion wi hou a s a is ically signi ican
educ ion in o he ma e nal and o sp ing
complica ions. The e ec s o in e en ions o
indi idual ma e nal and o sp ing complica ions
a e consis en i espec i e o he BMI o he mo he .
Addi ion o s udy le el da a om non-IPD s udies
o he IPD me a-analysis inc eased he p ecision o
es ima es, wi hou a change in he di ec ion o e ec ,
and showed addi ional bene i o ges a ional diabe es.
Among indi idual in e en ions, hose mainly based
on physical ac i i y lowe ed he odds o ges a ional
diabe es.
S eng hs and weaknesses o his s udy
To ou knowledge his is he i s IPD me a-analysis
o assess he di e en ial e ec s o die and physical
ac i i y based in e en ions o impo an , clinically
ele an ou comes, in subg oups o women who we e
iden i ied a p io i. Es ablishmen o he In e na ional
Weigh Managemen in P egnancy IPD Collabo a i e
G oup acili a ed he collabo a ion o key esea che s
in his a ea and p o ided access o he la ges IPD
in his special y. This allowed us o ex ac da a ha
we e no published, wi h la ge sample sizes o
ou comes such as p e e m bi h, small and la ge o
ges a ional age e uses, and admission o he neona al
in ensi e ca e uni o IPD han o s udy le el me a-
analysis. Fu he mo e, we we e able o minimise
he he e ogenei y in he popula ion by excluding
indi idual women who did no ul il he inclusion
c i e ia. We compa ed he quali y o s udies ha
con ibu ed o he IPD, which we e gene ally o highe
quali y han hose ha did no con ibu e IPD.
Table5 | Di e en ial e ec s o die and physical ac i i y based in e en ions on ma e nal and o sp ing composi e
ou comes in subg oups o p egnan women
Composi e ou comes
No o s udies
(No o women)
Odds a io*
(95% CI)
T ea men co a ia e in e ac ion
Coe icien ; 95% CI (95% PI) I2 (%)
Ma e nal
Baseline body mass index:
No mal 12 (2445) 0.91 (0.65 o 1.28) 1.00; 0.98 o 1.02 (0.98 o 1.02)† 0
O e weigh 19 (2222) 1.04 (0.86 o 1.26)
Obese 20 (4181) 0.92 (0.80 o 1.05)
Pa i y:
Nullipa ous 21 (4613) 0.87 (0.71 o 1.07) 1.03; 0.75 o 1.39 (0.53 o 2.00)‡ 34.0
Mul ipa ous 22 (4186) 0.92 (0.78 o 1.07)
E hnici y:
Whi e 15 (6510) 0.92 (0.79 o 1.07) 0.93; 0.63 o 1.37 (0.62 o 1.38)§ 0
Non-whi e 11 (917) 0.86 (0.63 o 1.17)
Age (yea s):
≥20 24 (8656) 0.91 (0.81 o 1.02) 1.01; 0.99 o 1.03 (0.99 o 1.03)¶ 0
<20 9 (172) 1.57 (0.66 o 3.71)
P e-exis ing medical condi ion**:
None 15 (3135) 0.85 (0.66 o 1.09) 1.44; 0.15 o 13.74 (0.03 o 76.75)†† 24.9
≥15 (89) 1.65 (0.36 o 7.51)
O sp ing
Baseline body mass index:
No mal 7 (1843) 0.93 (0.60 o 1.43) 0.98; 0.95 o 1.00 (0.94 o 1.02)† 18.5
O e weigh 12 (2065) 0.83 (0.61 o 1.13)
Obese 13 (4327) 0.92 (0.72 o 1.19)
Pa i y:
Nullipa ous 16 (4152) 0.97 (0.80 o 1.17) 0.94; 0.64 o 1.37 (0.39 o 2.28)‡ 35.5
Mul ipa ous 15 (4048) 0.91 (0.72 o 1.15)
E hnici y:
Whi e 11 (6018) 0.93 (0.79 o 1.08) 1.12; 0.75 o 1.68 (0.74 o 1.69)§ 0
Non-whi e 9 (939) 1.10 (0.78 o 1.54)
Age (yea s):
≥20 16 (8061) 0.95 (0.82 o 1.09) 1.01; 0.98, 1.04 (0.97 o 1.05)¶ 4.1
<20 7 (162) 1.01 (0.34 o 2.98)
P e-exis ing medical condi ion**:
None 12 (3407) 0.89 (0.74 o 1.08) 0.58; 0.03, 9.81 (<0.001 o 2440.15)†† 0
≥13 (63) 0.54 (0.04 o 7.52)
PI=p edic ion in e al.
*Model accoun ed o baseline weigh and clus e ing e ec .
†Pe uni o body mass index.
‡Mul ipa ous e sus nullipa ous.
§Non-whi e e sus whi e.
¶Pe yea o age.
**Diabe es melli us o hype ension.
††≥1 medical condi ion e sus none.