Pregestational Diabetes and Pregnancy

An Australian experience

We examined the current status of pregnancy complicated by preexisting diabetes in Australia. Data were collected on 180 pregnancies from 10 teaching hospitals (in NSW, Victoria, and Western Australia) with an interest in pregnancy complicated by diabetes, for the period from July 2003 to June 2004.

The majority of the pregnancies were complicated by type 2 (55%) rather than type 1 diabetes. The women with type 2 diabetes were significantly older (32.8 ± 5.4 years) than those with type 1 diabetes (30.9 ± 5.1 years, P = 0.014, independent t test). Type 2 diabetic women also had a shorter diabetes duration (4.4 ± 3.3 vs. 13.3 ± 8.2 years, P < 0.0001).

The outcomes were 172 (96.6%) live births at 37.1 ± 2.9 (mean ± SD) weeks of gestation. The mean weight was 3,473 ± 820 g (median 3,580 g), a result which would fall within the 87th and 96th centiles using the Gestation Network Centile Calculator (1). Sixty three percent of deliveries were by Caesarean section.

The survey did not capture early miscarriages. There were six (3.4%) neonatal deaths. One of these related to a termination for fear of congenital malformations. There were five stillbirths, giving a stillbirth rate of 2.8%, four times that seen in the general population. (In the NSW Midwives Database, the perinatal mortality, which includes stillbirths and later neonatal deaths, was 0.71 in 2002.) Five of the six deaths occurred in women with type 2 diabetes. Four of these women were of non-English speaking background, and none had received prepregnancy counseling or folate supplementation.

Prepregnancy counseling could be documented in only 19.8% of the women: 27.8% of those with type 1 diabetes and merely 12% of those with type 2 diabetes. Folate supplementation at the time of conception as a surrogate for planned pregnancy was documented in 45.7% of the women: 56.6% of those with type 1 diabetes, 36.4% of those with type 2 diabetes.

Neonatal hypoglycemia was common (25%), as was shoulder dystocia (8.1%). Congenital malformations were also common, with 8.1% major malformations and 12% minor malformations. A first-trimester HbA_1c was available for five of the pregnancies with a major congenital malformation and was 7.6 ± 2.1% compared with 7.1 ± 1.8% (n = 119) in those without a major congenital abnormality. In the NSW Birth Defects Register, the rate of major birth defects before 2002 was ∼2.1%. Thus, the rate of major malformation in our survey was four times that of the background population.

Type 2 diabetes is now the more common type of diabetes in women of reproductive age, and this will continue to increase based on the increasing prevalence of type 2 diabetes in this age-group documented in the AusDiab study (2). Pregnancies in patients with type 2 diabetes have significantly worse outcomes than the general population and are not more benign than pregnancies complicated by type 1 diabetes. We believe that these poor outcomes are at least in part due to the lack of attention directed to these women because of their relative social disadvantage and a perception that type 2 diabetes is not as severe a problem, even in pregnancy. Public health measures need to be taken to educate both the public and the medical profession about the dangers of type 2 diabetes and pregnancy.