Severe hypoglycaemia during pregnancy in women with Type 1 diabetes is common and planning pregnancy does not...

The aim of this study was to identify risk factors for severe hypoglycaemia (SH) in pregnancy in Type 1 diabetes, including associations with pregnancy planning and glycaemic control.

Clinical data including details of the pregnancy and its outcome, glycaemic control, frequency of SH and evidence of pregnancy planning were collected prospectively as part of a national audit of 160 pregnancies in women with Type 1 diabetes.

An episode of SH was experienced by 29.4% of women at some point during the pregnancy, with the percentage of women experiencing SH decreasing from 21.9% in the first trimester to 18.1% in trimester 2 and 10.9% in trimester 3. Longer duration of diabetes was associated with increased frequency of SH during pregnancy (r = 0.191, P = 0.012). A greater fall in glycated haemoglobin (HbA(1c)) between pre-pregnancy and the first trimester was not associated with increased risk of SH in trimester 1. Planned pregnancies had better glycaemic control but higher risk of SH in trimester 1 (P = 0.047). Women with pre-pregnancy retinopathy and current smokers had an increased risk of SH in trimester 3 (P = 0.029, P = 0.033).

SH is common during pregnancy and particularly in the first trimester. Planning pregnancy does not decrease the risk of SH. Improvements in glycaemic control at the start of pregnancy do not appear to increase the risk of SH. Education of women and their partners about the risks of SH and its management is essential when planning pregnancy.