Aims: To monitor pregnancies in women with pregestational Type 1 diabetes for pregnancy loss, congenital malformations and fetal growth parameters, in a geographically defined area in the north west of England.
Methods: Population cohort study of 547 pregnancies in women with Type 1 diabetes from maternity clinics in 10 centres over a 5-year period (1995-1999 inclusive). Main outcome measures were numbers and rates of miscarriages, stillbirths, neonatal and post-neonatal deaths; prevalence of congenital malformations; birth weight in relation to gestational age.
Results: Among 547 pregnancies, there were six (1.1%) pairs of liveborn twins, 439 (80.3%) liveborn singletons; 72 (13.2%) spontaneous abortions, 14 (2.6%) stillbirths and 16 (2.9%) terminations. Four of the terminations were performed because of congenital malformations. Both the stillbirth rate (30.1/1000 total births (95% confidence interval (CI) 16.6-50.0)), and prevalence of congenital malformations (84.3/1000 live births (95% CI 60.3-113.8)) were significantly higher than the local population (P < 0.001). When corrected for gestational age, mean birth weight in the sample was 1.3 sd greater than that of infants of non-diabetic mothers (P = 0.12). Infants with congenital malformations weighed less than those without.
Conclusion: In an unselected population, the infants of women with pregestational Type 1 diabetes mellitus have 6.4 times the reported risk of a congenital malformation and 5.1 times the reported risk of perinatal mortality than infants in the general population. Further improvements in the management of diabetes and pregnancy in these women are needed if the St Vincent's Declaration target is to be met.