Effect of pregnancy on microvascular complications in the diabetes control and complications trial. The Diabetes Control and Complications Trial Research Group

Abstract

Objective: To assess the effect of pregnancy on the development and progression of retinopathy and microalbuminuria in type 1 diabetes.

Research design and methods: We conducted longitudinal analyses of the Diabetes Control and Complications Trial (DCCT), a multicenter controlled clinical trial that compared intensive treatment with conventional diabetes therapy and studied 180 women who had 270 pregnancies and 500 women who did not become pregnant during an average of 6.5 years of follow-up. Women assigned to the conventional treatment group were changed to intensive therapy if they were planning pregnancy or as soon as possible after conception. Fundus photography was performed every 6 months, and the urinary albumin excretion rate (AER) was measured annually.

Results: Compared with nonpregnant women, pregnant women had a 1.63-fold greater risk of any worsening of retinopathy from before to during pregnancy (P < 0.05) in the intensive treatment group; the risk was 2.48-fold greater for pregnant vs. not pregnant women in the conventional group (P < 0.001). In the conventional group, the odds of > or =3-step progression from the baseline retinopathy level was >2.9-fold among pregnant vs. not pregnant women (P = 0.003). The odds ratio (OR) peaked during the second trimester (OR = 4.26, P = 0.001) and persisted as long as 12 months postpregnancy (OR = 2.87, P = 0.005). The level of AER during pregnancy in the intensive group, but not in the conventional group, was significantly elevated from the level at baseline, albeit in the normal range. Although individual patients had transient worsening of retinopathy during pregnancy, even to the proliferative level, at the end of the DCCT, mean levels of retinopathy and albuminuria in subjects who had become pregnant were similar to those in subjects who had not become pregnant within each treatment group.

Conclusions: Pregnancy in type 1 diabetes induces a transient increase in the risk of retinopathy; increased ophthalmologic surveillance is needed during pregnancy and the first year postpartum. The long-term risk of progression of early retinopathy and albumin excretion, however, does not appear to be increased by pregnancy.