Relationship between maternal hypoglycaemia and small-for-gestational-age infants according to maternal weight status: a retrospective cohort study in two hospitals

OBJECTIVE: The relationship between pre-pregnancy body mass index (BMI) and low glucose challenge test (GCT) results by maternal weight status has not been examined. This study aimed to clarify the relationship between a low GCT result and small for gestational age (SGA) by maternal weight status. DESIGN: A retrospective cohort study in 2 hospitals. SETTING: This study evaluated the obstetric records of women who delivered in a general community hospital and a tertiary perinatal care centre. PARTICIPANTS: The number of women who delivered in both hospitals between January 2012 and December 2013 and underwent GCT between 24 and 28 weeks of gestation was 2140. Participants with gestational diabetes mellitus or diabetes during pregnancy, and GCT results of ≥140 mg/dL were excluded. Finally, 1860 women were included in the study. PRIMARY AND SECONDARY OUTCOME MEASURES: The participants were divided into low-GCT (≤90 mg/dL) and non-low-GCT groups (91–139 mg/dL). The χ(2) tests and multivariate logistic regression analyses were conducted to investigate the association between low GCT results and SGA by maternal weight status. RESULTS: The incidence of SGA was 11.4% (212/1860), and 17.7% (330/1860) of the women showed low GCT results. The patients were divided into 3 groups according to their BMI (underweight, normal weight and obese). When the patients were analysed separately by their weight status after controlling for maternal age, pre-pregnancy maternal weight, maternal weight gain during pregnancy, pregnancy-induced hypertension, thyroid disease and difference in hospital, low GCT results were significantly associated with SGA (OR 2.10; 95% CI 1.14 to 3.89; p=0.02) in the underweight group. CONCLUSIONS: Low GCT result was associated with SGA at birth among underweight women. Examination of maternal glucose tolerance and fetal growth is necessary in future investigations.