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Journal of Obstetrics and Gynaecology (1999) Vol. 19, No. 5, 474± 476
OBSTETRICS
Obstetric hazards of maternal obesity
A. J. ROOPNARINESINGH, H. HOMER, B. BASSAW, A. SIRJUSINGH andS. ROOPNARINESINGHDepartment of Obstetrics and Gynaecology, University of the West Indies, Trinidad
Summary
To test the hypothesis that obesity represents a risk factor in
pregnancy, we conducted a prospective case± control study todetermine whether or not there was any divergence in the
obstetric outcome among 132 obese women from that in a
control group of 136 non-obese patients. Obese mothers hadan increased incidence of pregnancy-induced hypertension
and gestational diabetes but there was no signi® cant differ-ence in the duration of pregnancy or in the frequency of low
Apgar score at 1 minute. The favourable fetal outcome inobese parturients re¯ ects an increased awareness of the
possible medical and obstetric complications and an early
recourse to abdominal delivery.
IntroductionIn a previous analysis of our experience with obese
gravidae at this hospital, we reported a higher peri-
natal mortality rate and more depressed babies at birth
(Apgar score <7) than among non-obese mothers
(Naraynsingh et al., 1988). A policy of careful antenatal
surveillance for pregnancy-induced hypertension and
diabetes was instituted thereafter, and we adopted an
aggressive approach in favour of caesarean section
particularly for suspected fetal macrosomia.
The present investigation consists of a similar
appraisal of the reproductive performance of obese
parturients during the year 1997. The purpose of this
study was to establish whether or not there has been
any improvement in fetal outcome as a result of a
greater awareness of the major contributors to peri-
natal morbidity and mortality.
Patients and methodsOne hundred and thirty -two consecutive obese
pregnant patients were recruited from the antenatal
clinic of the Mount Hope Maternity Hospital which is
a tertiary care teaching institution. On the same day,
one or two controls were chosen from among the
antenatal clientele. None of these women had any
signi® cant pre-existing medical history at the booking
visit. The controls were matched for age, parity and
ethnicity. All patients were of low socioeconomic status.
Obesity was de® ned as a body mass index [weight
(kg)/height2
(m)] of ³ 30 at the ® rst antenatal visit. The
control group of 136 patients weighed between 50 and
65 kg with a body mass index of 20 ± 28.
All gravidae were routinely subjected to a 50 g oral
glucose screening test for diabetes, at least once in the
third trimester. Those with a plasma glucose value of
³ 140 mg/dl were further evaluated by a 75 g oral
glucose tolerance test.
Blood pressure was measured by the same observer
with the patient in a sitting position, using a mercury
sphygmomanometer and an appropriate-sized cuff.
Pregnancy-induced hypertension was de® ned as a blood
pressure of 140/90 mmHg or greater during the second
half of pregnancy in a previously normotensive woman.
If fetal macrosomia ( ³ 4000 g) was suspected on
abdominal palpation, caesarean section was embarked
upon, electively at 38 weeks or as an emergency, intra-
partum.
The antenatal course, gestational age at delivery,
mode of delivery and fetal outcome in terms of birth-
weight, Apgar scores and perinatal mortality were
documented.
Statistical analysis was employed using the c 2and
odds ratio (OR) and its 95% con® dence interval (CI).
A P value >0´05 was not considered signi® cant.
ResultsThe incidence of pregnancy-induced hypertension was
signi® cantly higher among obese patients (13´6% vs.
2´9%; P<0´01).
The incidence of diabetes among obese mothers was
higher than the control group but this difference was
not statistically signi® cant (11´4% vs. 6´5%; P>0´05).
There was no signi® cant difference in the incidence
of preterm ( £ 37 weeks) or post-term ( ³ 42 weeks)
deliveries between the obese and the control group
(Table I).
The caesarean section rate among obese patients
was almost twice that in the control group (26´5% vs.
14´7%; OR=1´8, 95% CI: 1´02± 3´28, P<0´05).
Obese mothers were delivered of more macrosomic
babies and fewer infants weighing less than 2500 g than
were non-obese mothers (Table II).
Table III reveals that the frequency of a low Apgar
score at 1 minute was similar in both groups (10´6% vs.
10´9%). Of the nine macrosomic infants in the obese
group, four were delivered by caesarean section with
zero mortality and of the ® ve delivered vaginally, one
developed shoulder dystocia and intrapartum asphyxia,
and died in the early neonatal period. The single
stillbirth in the obese group was an intrauterine demise
due to severe pre-eclampsia at 32 weeks. The perinatal
mortality rates in obese mothers and controls were
14/1000 and 6/1000, respectively. There were no
maternal deaths.
Correspondence to: Professor S. Roopnarinesingh, Mount Hope Women’s Hospital, Champs Fleurs, Trinidad.
ISSN 0144± 3615 print/ISSN 1364± 6893 online/99/050474± 03 � Institute of Obstetrics and Gynaecology Trust, 1999
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DiscussionThe medical-obstetric risk factors operating during the
antepartum period in obese pregnant patients have
remained unchanged over the past ® ve decades
(Douglas and Scadron, 1951; Tracy and Miller, 1969;
Roopnarinesingh and Pathak, 1970; Gross et al., 1980;
Konje et al., 1993). Our results verify that pregnancy-
induced hypertension is the principal medical complica-
tion in the obese mother (Kerr, 1962; Treharne, 1984).
Despite this ® nding, there is nothing we are currently
able to do as clinicians to prevent the development of
this disease. Imposition of caloric restrictions is not
recommended (Abrams, 1994) and how to manage this
disorder and achieve good perinatal outcome remains
a clinical challenge.
Previous correlations between maternal obesity and
gestational diabetes have been reported (Edwards et
al., 1978; Naraynsingh et al., 1988). The present study
reveals that although diabetes is more prevalent in obese
patients, the difference was not statistically significant.
This is probably due to the high prevalence of diabetes
in our native population (Poon King et al., 1968;
Bassaw et al., 1995). Seen in perspective, our analysis
suggests that one in nine obese mothers will develop
gestational diabetes whereas the frequency of diabetes
in pregnancy among the hospital population is one in
100 (Manjoo et al., 1987). These ® ndings reinforce the
view that maternal obesity is an important risk factor
in screening for gestational diabetes (Plante, 1998), a
disorder which can be treated adequately, in contrast
to pregnancy-induced hypertension.
With respect to the in¯ uence of obesity on birth-
weight, our results con® rm that obese parturients are
delivered of more macrosomic and fewer low birth-
weight babies than are non-obese mothers. That big
mothers tend to have big babies has been a consistent
observation in the past (Witten, 1958; Edwards et al.,
1978; Bromwich, 1986) and it has been speculated that
the obese mother may have an overriding metabolic
effect that overcomes the multiple risk factors for having
low birthweight infants (Gross et al., 1980). In view of
the potential dangers of vaginal delivery of large babies,
we consider it prudent to predict fetal size in all obese
patients before deciding on the mode of delivery.
However, correct identi® cation of a large baby has its
limitations, either by ultrasound (Tamura et al., 1986)
or clinically (Parks and Ziel, 1978; Svigos, 1981; Rose
and McCallum, 1987) and in obese mothers, this is
further compounded by the inherent difficulty in
palpating a fetus through a sea of fat. The present
study demonstrates this drawback since only four of
the nine macrosomic infants were identi® ed before birth
by external palpation.
In our study a decade ago, we reported a perinatal
mortality rate of 3´7% and a caesarean section rate of
16´7% in obese gravidae (Naraynsingh et al., 1988). In
the current investigation, these ® gures are 1´4% and
26´5%, respectively, suggesting an inverse relationship
between these two parameters. This observation gives
some logical support to the inference that appropriate
use of caesarean section will contribute to diminishing
perinatal mortality. The achievement of a favourable
fetal outcome despite the prevalence of diabetes and
hypertension corroborates an Australian report (Calan-
dra et al., 1981) but differs from the British and
Jamaican experience (Kerr, 1962; Roopnarinesingh and
Pathak, 1970, respectively). These uniformly excellent
results in Trinidad may well be due to the implementa-
tion of attentive antenatal care, routine screening for
diabetes and a low threshold for operative intervention
in obese pregnant patients.
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Table I. Gestational age at delivery
Gestational age (weeks) Obese group (n) Control group (n) P value
£ 37 10 (7´6%) 19 (13´9%) >0´05>37± <42 112 (84´9%) 107 (78´7%) >0´05³ 42 10 (7´6%) 10 (7´4%) >0´05
n indicates the number of patients.
Table II. Comparison of birthweight between obese mothers and controls
Birthweight (grams) Obese (n) Non-obese (n) P value
<2500 5 18 <0´05³ 2500± 3999 118 117 NS>4000 9 1 <0´001
n indicates the number of patients.
Table III. Fetal outcome in obese mothers and controls
Complication Obese group (n) Control group (n)
Apgar score <7 14 (10´6%) 17 (10´9%)Shoulder dystocia 1 0Stillbirth 1 1Neonatal death 1 0
n indicates the number of patients.
Obstetric hazards of maternal obesity 475J
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