Comparison of growth and body composition of infants born to mothers with, and those without, gestational diabetes mellitus
Date
2021
Authors
Ngobeni, Martha
Journal Title
Journal ISSN
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Abstract
In low-middle-income countries like South Africa, the application of selective screening for
gestational diabetes mellitus (GDM) is based on the presence of risk factors. Gestational diabetes
mellitus is public health problem which results in short- and long-term consequences, like obesity,
type 2 diabetes mellitus (T2DM) and cardiovascular disease for both the mother and child later in
life.
Children exposed to GDM in utero are likely to be born macrosomic resulting from increased body
fat composition. Early life exposures alter body composition by increasing adipose tissue while
increasing the risk of non-communicable diseases (NCD). Furthermore, metabolic factors may
influence rapid growth in infancy by increasing adipose tissue which increases the risk of NCD
later in life.
Aim: This study aimed to assess the uptake of universal screening for GDM and to investigate the
relationship between maternal factors and birth outcomes (growth and body composition) in
infants born to mothers with and those without GDM.
Design: The study comprised of two sections: (i) the uptake of universal screening and
effectiveness of selective screening for GDM (ii) a case-control longitudinal comparative study
that followed infants born to mothers with (n = 22) and without (n = 110) GDM from birth until
six months of age.
Data collection and analysis: Pregnant women who had been referred from district hospitals and
local clinics in Soweto and surrounding areas (Orange Farm and Lenasia) to Chris Hani
Baragwanath Academic Hospital (CHBAH) were invited to participate in the study. The following
inclusion criteria were applied: women who were less than 20 weeks pregnant at recruitment, black
South African (ethnicity verbally reported), 18 years of age or older and pregnant with singleton
pregnancies that were naturally conceived. Furthermore, no foetal abnormalities could have been
detected and the women could not have been diagnosed with pre-existing diabetes or epilepsy.
These women were booked to have an oral glucose tolerance test (OGTT) performed between 24-
28 weeks gestation. Body composition data on the infants were obtained from air-displacement
plethysmography. Other collected data included socio-economic status (SES), obstetric history and
anthropometric measurements of infants and mothers. Z-scores (weight, length, head
circumference, body mass index (BMI)) and conditionals (weight and length) were treated as
outcome variables. Data analysis included descriptive, bivariates and multivariate analyses which
were performed in STATA 14. The probability value of < 0.05 was considered statistically
significant.
Results: The majority of the pregnant women were screened for GDM but 43% of them failed to
take up the offer of an OGTT for various reasons, including lack interest in testing, difficulty in
getting time off at work, relocating to another province, previously tested at CHBAH and kept
rescheduling but failed to attend; these women were therefore excluded.
At birth, the mean ± standard deviation weight of infants born to mothers with GDM was 3396g ±
502 while the mean weight for infants born to mothers without GDM was 3472 g ± 610 (p = 0.587).
At six months, the mean weight was 7401 g ± 853 of infants born to mothers with GDM compared
to 7389 g ± 1240 of infants born to mothers without GDM (p = 0.948). Despite there being no
statistically significant difference in length (p = 0.721) at birth, the length of infants exposed to
GDM was 49.64 cm ± 3.17 slightly longer than unexposed to GDM was 49.37 cm ± 3.32. At six
months of growth, the mean lengths were 64.04 cm ± 1.88 versus 64.49 cm ± 2.98 in infants
exposed and unexposed to GDM respectively (p = 0.511). There was no statistical difference at
birth in the median head circumference of infants born to women with, 35.48 cm (34.63-36.40)
and without, 35.15 cm (34.90-35.60) GDM (p = 0.351). Despite the statistical non-significance at
six months, the head circumference of infants born to women with GDM were slightly bigger than
infants born to women without GDM (p = 0.963).
According to the BMI-for-age, infants in both groups were not overweight or obese in the first six
months of life. The weight gain of infants exposed to GDM was significant at one (p = 0.005),
three (p < 0.001), four (p = 0.026) and six months (p < 0.001) of age compared to the infants
unexposed to GDM. In addition the conditional length growth of the infants born to mothers with
GDM showed significant growth at birth (p = 0.004), two (p = 0.001) and five months (p = 0.049)
compared to infants born to mothers without GDM in the first six months of life
Description
A dissertation submitted in fulfilment of the requirements for the degree of Master of Science in Medicine to the Faculty of Health Sciences, School of Clinical Medicine, University of the Witwatersrand, Johannesburg, 2021