Preeclampsia in pregnancies with and without diabetes; the associations with placental weight. A population study of 655 842 pregnancies

Abstract

Introduction Women with diabetes are at increased risk of preeclampsia, and women with diabetes tend to deliver placentas and offspring that are large-for-gestational-age. We therefore studied placental weight in preeclamptic pregnancies according to maternal diabetes status. Material and methods Information on all singleton births from 1999 through 2010 (n = 655 842) were obtained from the Medical Birth Registry of Norway. We used z-scores of placental weight to adjust for differences in gestational age at birth between deliveries, and compared the distribution of placental weight z-scores, in deciles, in preeclamptic pregnancies with and without diabetes, and in non-preeclamptic pregnancies with and without diabetes. Results Overall, the prevalence of preeclampsia was higher in pregnancies with diabetes than in pregnancies without diabetes (9.9% vs. 3.6%). Among preeclamptic pregnancies, having a placental weight in the highest decile was nearly three times more frequent (28.8%) in pregnancies with diabetes than in pregnancies without diabetes (9.8%). In the lowest decile, preeclamptic pregnancies with diabetes were underrepresented (7.5%), and preeclamptic pregnancies without diabetes were overrepresented (13.6%). Among pregnancies with preterm delivery, the above patterns were more pronounced, with 30.1% of the placentas in in preeclamptic pregnancies with diabetes in the highest decile, and 19.5% of the placentas in preeclamptic pregnancies without diabetes in the lowest decile. Conclusions These results suggest that women with diabetes who develop preeclampsia have a higher placental weight than other women with preeclampsia or non-preeclamptic women.