Antenatal Corticosteroid Administration in Women with Diabetes in Pregnancy

Abstract

Aim: Diabetes is the most common medical disorder in pregnancy and many women with diabetes in pregnancy (DIP) give birth preterm. Antenatal corticosteroids (ANC) decrease complications in babies born preterm, but there is little evidence about their effects in women with DIP. ANC increase maternal hyperglycaemia and thus potentially affect neonatal glycaemic control. The focus of this thesis is to describe ANC administration to mothers with DIP and to analyse the impact on maternal and neonatal glycaemic control. Methods: Reported ANC prescribing practices of obstetricians in New Zealand and Australia to women with and without diabetes in pregnancy were identified through an on-line survey. Actual prescribing practices were identified from a cohort of 647 women with pre-existing or gestational diabetes receiving ANC at a tertiary New Zealand hospital from 2006-2016. Reported and observed ANC practices were compared to existing guideline recommendations. Maternal and neonatal blood glucose concentration data were collected and associations with ANC administration were analysed. A prospective protocol using continuous glucose monitoring was developed to assess the relationship between maternal and neonatal glycaemia after ANC. Findings: Survey-reported ANC administration was consistent with the guidelines for women receiving ANC at <35 weeks or a repeat course at <33 weeks. Contrary to the guidelines, reported ANC administration was common at ≥35 weeks and ≥33 weeks for a repeat course. The reported ANC administration pattern was similar in women with and without DIP. Observed patterns of ANC administration in the cohort were similar to those reported. Maternal hyperglycaemia (>7 mmol/L) after ANC administration was observed in 99% of women with type-1 diabetes, 95% of women with type-2 diabetes and 90% of women with gestational diabetes. Neonatal hypoglycaemia (<2.6 mmol/L) was common in babies born to mothers with DIP, particularly when ANC were administered 12 to 48 hours before birth. Maternal hyperglycaemia within 24 hours of birth was associated with an increased risk of neonatal hypoglycaemia (OR 1.51, 95%CI 1.10-2.07, p=0.01). Conclusions: Women with DIP receive ANC largely in keeping with current recommendations, although some receive ANC later in pregnancy than recommended. The relationships between maternal and neonatal glycaemia suggest that maternal hyperglycaemia increases the risk of neonatal hypoglycaemia. Further research should investigate approaches to mitigate this risk.