Association of maternal insulin resistance with neonatal insulin resistance and body composition/size: a prospective cohort study in a sub-Saharan African population.

Purpose: We prospectively evaluated the association of the insulin resistance of third-trimester Nigerian pregnant women with their newborn infants' insulin resistance and birth size. Pregnancy-associated insulin resistance (IR), often assessed with homeostatic model assessment of IR (HOMA-IR), is associated, especially among women with gestational diabetes (GDM), with abnormal neonatal birth size and body composition, predisposing the baby to metabolic disorders like diabetes and obesity. The associations of maternal IR with neonatal IR, birth size and body composition are less studied in nondiabetic pregnant women, especially in sub-Saharan settings like Nigeria.

Methods: We originally recruited 401 third trimester, nondiabetic pregnant women to a prospective cohort study, followed up until birth. Blood samples of mothers and babies were obtained, respectively, at recruitment and within 24 hours postbirth for fasting serum glucose (FSG) and insulin (FSI) assays, and HOMA-IR was calculated as [(FSI × FSG)/22.5)].

Results: Complete data for 150 mother-baby dyads was analysed: the mothers, with a mean (standard deviation [SD]) age of 31.6 (4.5) years, had live births at a mean (SD) gestational age of 39.2 weeks. The proportions of infants with wasting, stunting, impaired fetal growth (either wasting or stunted), small-for-gestation-age, large-for-gestational-age, low birthweight, and macrosomia were 4.2% (95% confidence interval, 1.1-10.3), 19.7% (12.9-28.0), 23.1% (15.8-31.8), 10.1% (5.3-17.0), 12.6% (7.2-19.9), 0.8% (0.02-4.5), and 5.0% (1.8-10.5), respectively. Maternal HOMA-IR was not associated with neonatal HOMA-IR (p=0.837), birth weight (p=0.416) or body composition measured with weight-length ratio (p=0.524), but birth weight was independently predicted by maternal weight (p=0.006), body mass index (p=0.001), and parity (p=0.012).

Conclusion: In this nondiabetic/non-GDM cohort, maternal HOMA-IR was not associated with neonatal IR, body size or body composition. Larger studies are required to confirm these findings, with addi-tional inclusion of mothers with hyperglycaemia for comparison.