jurnal body fat in spe risk

8/9/2019 Jurnal Body Fat in SPE Risk

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Research ajog.org

OBSTETRICS

Early-pregnancy percent body fat

in relation topreeclampsia risk inobese omenLindsay K. Sween, MD; Andrew D. Althouse, PhD;James M. Roberts, MD

OB!ECTI"E# The p$rpose of this st$dyas to identify differences of early-pregnancy body fat percentage and bodymass inde% &B'I( beteen obese omenthat e%perienced preeclampsia and thoseho did not.

ST)*+ *ESI,# e performed an analysis of the

/renatal E%pos$res and /reeclampsia /re0ention 1

longit$dinal cohort st$dy of preeclampsia

mechanisms in obese and o0ereight omen.

omen completed 2$estionnaires regarding their

health beha0iors3 had hematocrit le0el4 eight and

height4 and aist and hip circ$mferences

meas$red4 and had resistance and reactance

meas$red by bioelectric impedance analysis

machine d$ring the first4 second4 and third

trimesters. Total body ater4 fat mass4 and percent

body fat ere calc$lated ith the $se of pregnancy-

specific form$las. /reeclampsia as assessed ith

the clinical definition and a research definition

&clinical preeclampsia pl$s hyper$ricemia(. 5ogistic

regression models ere constr$cted to analy6e

early-pregnancy B'I and body fat percentage

&meas$red at 78.9 1.8 eeksof gestation( as predictors of preeclampsia o$tcomes.

RES)5TS# Three h$ndred se0enty-

three omen ere incl$ded in the

analysis# 18 omen had

preeclampsia by clinical definition

&:.8;(4 and 7< omen had

preeclampsia by the research

definition &1.:;(. There as no

relationship beteen B'I and

preeclampsia risk in obese omen3

hoe0er4 body fat percentage as

associated signifi-cantly ith

increased risk of both the clinical

definition of preeclampsia and the

research definition. In 91= obese

omen4 a 7; increase in body fat

as associated ith appro%imately

79; increased odds of clinical

preeclampsia and 9ey ords#bioelectricimpedanceanalysis4 body fatpercentage4 bodymass inde%4

obesity4preeclampsia

Cite this article as# Seen 5>4

?ltho$se ?*4 Roberts !'.Early-pregnancy percent

body fat inrelation to

preeclampsiarisk in obese

omen. ?m ! Obstet ,ynecol987@3979#:


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ealth.

The a$thors report noconflict of interest.

Corresponding a$thor#!ames '. Roberts4 '*.

jrobertsmri.magee.ed$

8889-=1A:FG1D.88 H 987@/$blished by Else0ier Inc.

http#FFd%.doi.orgF78.787DFj.ajog.987


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a7o.or Obstetrics Research

mellitus, renal disease, other medical complications, or multiple

estations were e(cluded. 6omen were recruited in early

prenancy %rom the outpatient clinics o% Maee"6omens

8ospital in Pittsburh, PA, and had body composi"tion assessed

by bioelectrical impedance in the first, second, and third

trimesters -at appro(imately '9, )9, and +! wee*s o% estation0.

he outpatient clinics ser1e primarily low"income, uninsured,unmarried, blac*, or biracial women; +:+ women had complete

early"prenancy -first trimester0 data and were eliible %or

inclusion in this study.

'eas$rements

6omen completed a uestionnaire reardin their health

beha1iors, repro"ducti1e history, and demoraphic char"

acteristics. Standin heiht and waist and hip circum%erences

were measured twice %or accuracy, and the mean o% the ) 1alues

was used. 6aist circum%erence was measured at the natural waist

with the center o% the na1el as a physical landmar*. 8ip

circum%erence was measured 7ust below the bony promi"nence o% the anterior superior iliac spine. 5arly prenancy M/ was

calculated %rom weiht and heiht measurements at the first 1isit-at '9.+ ).< wee*s o% estation0.

reactancemeasured by a/A machine andthe patientJsheiht, weiht,abdominalcircum%erence,and hemat"ocrit

le1el. 6 durin prenancy wascalculated with theeuation deter"mined by Lu*as*i

et al: -able '0.

6 was thenused to estimatethe weiht o% body%at. 6e deri1ed aneuation %or weiht o% %at massat any estational

ae based on theeuations pro1ided

by 1an Raai7 et al.#

6ater content o% %at %ree mass wascalculated usintwo separateeuations, one %or 9 to '9 wee*s o% estation and one%or '9 to 29 wee*so% estation, thatwere deri1ed %rom=iure ' o% 1an

Raai7 et al.# hese

euations were1alidated aainstdeuterium dilution

spaces: and under"

water weihin.#

8ematocritle1el wasmeasured in bloodsamples that wereobtained by1enipuncture.

/reeclampsiadefinition

6e used )

definitions o% preeclampsia. he

first matches thecurrent American

>ollee o%

?bstetrics and

@ynecoloy

definition when we

bean the study, inwhich a woman

with pre1iously

normal blood

pressure has a

blood pressure

'29 andor


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random urine sample, a catheteri3ed urine sample with 'þ

protein, or a protein"creatinine ratio M9.+. A 7ury re1iewed the

abstracted medical

records to

determine that

criteria %or

preeclampsia had

been satisfied.

Resistance and reactance were measured

with a Buantum /C ioelec"trical

/mpedance Analy3er -RJL Systems, >linton

ownship, M/0. Measurements were ta*en

with the patient lyin supine with arms at a

+9"deree anle %rom the body and with the

les not touchin so as not to disrupt the

electrical circuit. 5lectrodes were attached

in a tetrapolar arranement, with )electrodes on the dorsal sur%ace o% the riht

%oot and ) electrodes on the dorsal sur%ace

o% the riht hand, ' pro(imally and '

distally. he distal electrodes act as the

ener"atin electrodes that transmit a small,

painless

electrical

current; the

pro(imal

electrodes

recei1e the

electric

current and

measure the1oltae drop

between the

riht hand

and riht

%oot.!

Bodycompositioncalc$lations

/A theoryestimates

total bodywater -60

based ontheresistanceand

T?B5E 7

Bodycompositione2$ation

s"ariable

Total body ater4 5

eight of fat mass4 kg

78 k

98 k

18 k


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Research Obstetrics a7o.or

Statistical methods

aseline data were described with the mean standard de1iation

%or contin"uous 1ariables and percentaes %or cate"oric 1ariables

in the total population and separately by preeclampsia status.

Potential di%%erences between women with normal prenancies or

with pre"eclampsia were e1aluated with the use o% t tests %or

continuous 1ariables -eual 1ariances unless otherwise called %or;uneual 1ariances test used where appropriate0 and c) tests %or cateoric di%%erences -=isher e(act test in cases where e(pected

cell counts were N!0. his study %ocused on early prenancy M/

and body %at percentae as pre"dictors o% preeclampsia outcomes;

there%ore, first"trimester measurements o% M/ and body %at were

used in all primary analyses. ody %at percentae was e(amined

as a %unction o% M/; the Pearson correlation coe% ficient is pre"

sented to assess the linear relationship. Lac*in su% ficient sample

si3e to test appropriately %or interaction between M/ and percent

body %at, we instead assessed the relationship between body %at

and preeclampsia by testin %or di%"%erences in percent body %at

between women with preeclampsia and healthy control sub7ectswithin each o% the 6orld 8ealth ?rani3ation M/ classifications

usin t tests -a test with uneual 1ariance where appropriate0.

Loistic reression models were constructed to analy3e M/ and

body %at percentae as continuous 1ariables and allow ad7ustment

%or a limited selection o% potential con"%ounders. ecause the

Prenatal 5(po"sures and Preeclampsia Pre1ention + study was

desined to compare obese women who did or did not e(perience

preeclampsia, we initially limited our loistic reression models

only to obese women. 6e also per%ormed a secondary analysis

that included all participants because o% the surprisinly hih

rates o% preeclampsia in the lean and o1er"weiht women -by the

clinical defini"tion, :.4


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1alues N .9! were considered statistically preeclampsia ris* by both the researchsinificant. and clinical definition. =or each '$ in"

crease in body %at, the ris* o% clinical

RES)5TS preeclampsia increased ')$ -odds ratioStudy participants were aed )+.: 2.' E?RF, '.')2;

E>/F, '.9'#e'.)290, and the ris* o% years; 4+$ o% them were blac*, and

)9$ o% them were smo*ers -able )0. preeclampsia by the research definition) increased )2$ -?R, '.)+

he a1erae M/ was ++.' :.# *m ;'.9!2e'.2!!0. hese relationships were by study desin, most participants were

o1erweiht -)).9$0 or obese -42.'$0. strenthened slihtly when we ad7usted

@estational diabetes mellitus was the model %or ae, race, and smo*in

more common in women in the both status -able 20. 6e considered models

clinical -4.

which suests that body %at percentae 9.

fi compared with '.)< -/,8ealth ?rani3ation M/ classi cations,

only in the hihest cateory o% obese '.92e'.4'0 %or blac* women. 6e did not

women -M/ M29 *m)0 was the body ha1e a su% ficiently lare sample to

fi %ormally test interaction by race.%at percentae sini cantly hiher in

women who e(perienced preeclampsia 6hen we e(amined these relation"

compared with those women who did ships in all women -includin the lean

not -able +0. and o1erweiht women0, neither M/

6e compared M/ and percent nor body %at percentae was associated

body %at as predictors o% preeclampsia sinificantly with increased ris* o% pre") eclampsia by the clinical definition or

in obese women -M/ +9 *m ;the research definition -able !0, whichable 20. 8iher M/ was associated

sinificantly with hiher ris* %or the suested that the relationship betweenresearch definition o% preeclampsia, but percent body %at and preeclampsianot the clinical definition. he e%%ect was was present only in the obese women.no loner sinificant a%ter ad7ustment hese relationships did not 1ary sinifi"%or ae, race, and smo*in status. /n cantly when we ad7usted %or estational

contrast, there was a sinificant rela" diabetes mellitus, waist circum%erence,tionship between percent body %at and or waisthip ratio.

:


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s t e t r i c s I , y n e c ol o g y

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O b s t e t r i c s

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I,)RE

The relationship beteen B'I and percentage ofbody fat

opreeclampsia

reeclampsia

:8

A8 RS T 8.DD1

D8

F a t

@8

% B o d

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T?B5E 1

*istrib$tion of body fatpercentages

Body mass inde% classification

5ean

O0ereight

Obese class 7

Obese class 9

Obese class 1Seen. /ercent body fat andpreeclampsia risk. ?m ! Obstet ,ynecol987@.


11/15

:


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a7o.or Obstetrics Research

T?B5E <

Relationships beteen body fat percentage and risk of preeclampsia# obese participants onlyOdds ratio

/redictor O$tcome )nadj$sted =@; confidence inter0al ?dj$steda

=@; confidence inter0al

Body mass inde% Clinical preeclampsia &n O 7=( 7.87A 8.=

=urthermore, this

study was desined

to recruit women

with M/ M+9

*m), and most

studies that ha1e

in1estiated the

relationship

between

preprenancy M/

and preeclampsia

ha1e had small

sample si3es o% women with M/

M+! *m). odnar

et al2 %ound that the

?Rs o%

preeclampsia bean

trendin downward

a%ter M/ +!

*m), althouh

they remained M'.9compared with

M/ )' *m).

Rela"tionship

between M/ and

preeclampsia may

become more ill"

defined at 1ery hihM/s, i1en the

1aryin percent

body %at and body

%at distributions

-e, central,

abdominal,

peripheral, or

1isceral0 betweenobese indi1iduals.

Despite these

possible

e(planations, both

the de1iation %rom


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the well"established association between increasin M/ and

ele1ated preeclampsia ris* and the un"usually hih incidence o%

preeclampsia amon the lean and o1erweiht women do raise

uestions about the

representa"ti1e

nature o% this

cohort.

T?B5E @

Relationships beteen obesity

metricsand riskofpreeclam

psia# allpatients

/redictor

Body mass inde%

Body fat

Research preeclampsia &n O 7<a ?dj$sted for age4 race4 and smoking stat$s.

Seen. /ercent body fat and preeclampsia risk. ?m! Obstet ,ynecol 987@.

!?)?R+ 987@ ?merican !o$rnal of Obstetrics ,ynecology :


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Another challene encountered in this study was the unusually

hih rates o% preeclampsia in the lean and o1erweiht women.

he o1erall rate o% preeclampsia has not chaned dramatically in

our Pittsburh population, which suests that the hih incidence

o% preeclampsia may be an aberrant findin that is related to theintentionally small numbers o% lean and o1erweiht women.

Alterna"ti1ely, the cohort is 4+$ blac* women,%or whom the literature is mi(ed with reards to preeclampsia

ris*.+,'4,':

/n one

study, lean blac* women were more li*ely to e(perience

preeclampsia than lean white women, but the trend re1ersed at

M/ M)! *m).+ hus, the lare number o% blac* women in the

lean cohort may e(plain the hih le1els o% preeclampsia in this

roup. /n our study, when we dichotomi3ed by race, there was no

sinificant relationship between body %at percentae in whiteobese women and preeclampsia ris*, probably because o% a

smaller number o% cases in this subset. /n obese blac* women,

there was a sinificant relationship between increasin body %at

percentae and ris* o% preeclampsia by the research, but not bythe clinical definition. his findin is also probably because o% a

small sample si3e in the research definition subroup and not atrue racial interaction. /t was an un%ortunate limitation o% this

study that the sample o% women who e(peri"enced preeclampsia

was not lare enouh to assess adeuately the impact o% body %at

percentae by race.

here were additional limitations in this study. his cohort had

a small number o% cases -+9 cases by the clinical definition, o% which '2 cases also fit the research definition0, which led to wide

confidence inter1als %or some M/ and

body %at percentae

1alues. =urther, we

did not ad7ust %or

multiple

comparisons in our

reression

modelin, which

allowed the possibility o% a

spurious result

bein interpreted as

positi1e; howe1er,

we belie1ed that

the application o% a

particularly harsh

ad7ustment o% the

sinificance le1el

would ha1e made it

impossible to

detect any e%%ect ina cohort with

relati1ely %ew

cases. 6e ad7usted

the loistic

reression model

%or ae, race, and

smo*in durin

prenancy but

could not account

%or other potential

co1ariates, such as

preprenancy and

prenancy diet and

e(ercise habits.

his study

supports the

relationship o% %at

to preeclampsia.

Subseuent lon"

itudinal,

multicenter trials

with larer case

numbers are

needed to %urther

assess the utility o%

/A"determined

body %at

percentae in the

prediction o% pre"

eclampsia onset. -

REERECES

1. ?merican College

of Obstetricians and

,y- necologists.*iagnosis andmanagement of preeclampsia andeclampsia. ?CO,Committee on

/ractice B$lletins#Obstetrics. ?CO,practice b$lletin no.11. Obstet ,ynecol98893==# 7@=-DA.

2.Roberts !'4

,ammill S./reeclampsia recentinsights.ypertension

988@3lebanoff '?4 ess RB4Roberts !'./repregnancy bodymass inde% and theocc$rrence of se0ere hy-pertensi0e disordersof pregnancy.Epidemi- ology988A37:#91opp

5E4 >ing !C4 ong

4 'ayclin /5. l$id

changes d$ring

pregnancy# $se of

bioimpedance

spectroscopy. ! ?ppl

/hysiol 7==@3A:#781A-

4 Roberts 5'4Bron '?. /lasma$ric acid remains amarker of poor o$tcome in hy-

pertensi0epregnancy# aretrospecti0e cohortst$dy. B!O,9879377=#+4 et

al. )ric acid is as

important as

protein$ria in

identifying fetal risk in

omen ith

gestational hyperten-

sion. ypertension

988@3


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0ariations on the theme. /lacenta 988=391&s$ppl(#S19-A.

13. B$rton ,!4 oods ?4 !a$nia$% E4 >ingdom !C/.

Rheological and physiological conse2$ences of con0ersion of thematernal spiral arteries for $teroplacental blood flo d$r- ing h$manpregnancy. /lacenta 988=318#

jurnal body fat in spe risk

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