1. Singleton pregnancy
2. Gestational age of ≥ 37 weeks at the time of delivery
3. Availability of documented records of maternal
weight and height at the booking visit.
The exclusion criteria were:
1. Documented history of type 1 or type 2 diabetes
mellitus prior to the index pregnancy.
2. Multiple- pregnancy.
3. Women who were not screened for gestational
diabetes during the index pregnancy.
All women booked for antenatal care at KKUH are
screened for pre-existing diabetes mellitus using fasting
blood glucose (FBG) during their first antenatal visit.
Values above 5.3 mmol/l indicate a full oral glucose
tolerance test (OGTT). Further screening is carried
out between 24–28 gestation weeks. Oral glucose
(50 g) was administered, regardless of the time of the
last meal. Venous plasma glucose was measured 1 h later.
A value of 7.8 mmol/l (140 mg/dl) or more indicated the
need for a full diagnostic OGTT. The diagnosis of GDM
is based on the results of a 3-h, 100-g OGTT, interpreted
according to the diagnostic criteria of Carpenter and Coustan
[19]. Definitive diagnosis requires that two or more of
the venous plasma glucose concentrations meet or exceed:
fasting, 5.3 mmol/l (95 mg/dl), 1 h 10.0 mmol/l (180 mg/dl),
2 h 8.6 mmol/l (155 mg/dl) and 3 h 7.8 mmol/l (140 mg/dl).
Once diagnosed, women with GDM follow a specific
course of treatment including nutritional therapy and
counseling together with antenatal fetal surveillance.
Insulin therapy is introduced when nutritional therapy
fails to maintain the FBG at 5.8 mmol/l (105 mg /100 ml)
and/or the 2 h postprandial at 7.8 mmol/l (140 mg/dl).
Due to the proven effect of tobacco smoking, including
environmental tobacco smoke (ETS) exposure, on
the pregnancy outcomes, we collected data on maternal
smoking status. We considered women to be exposed to
ETS when the husband or one of the children smokes at
home. Duration of exposure to ETS was not reported in
this study as only 30% of the participants could recall
the duration of exposure.
The BMI was calculated for each subject using the maternal
weight and height recorded during the booking
visit, according to the following equation; BMI = weight
(kg)/height (m)2. Women were booked for their first
antenatal visit during the first or the second trimester of
pregnancy, subject to availability of appointments. To investigate
the independent effect of maternal obesity and
GDM on the pregnancy outcomes, women were divided
into two groups based on the BMI, non-obese with
BMI < 30 kg/m2 and obese with BMI ≥ 30 kg/m2. Further
stratification of the study population into a total
of four groups was based on the results of the GDM
screening as follows; women with no GDM and who were
not obese were considered the control group, second
group was women who had GDM but were not obese,
third group was women who were obese but did not have
GDM and the fourth group were women with both obesity
and GDM.
Data on the demographic and reproductive characteristics
in addition to data on the outcomes of pregnancies
were collected from the participants’ medical records,
after delivery in the post-natal ward, using a pre-designed
data collection sheet. Data on exposure to tobacco smoke
were collected from the participants in the postnatal ward.
The maternal characteristics included in the study were;
maternal age, parity, booking visit weight and height,