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.