The Case of Perinatal Mortality

Recent studies show that the infants of women with pregestational diabetes have a 4to 6-fold increased risk of PNM reaching 28 to 48 per 10003-14. However, the true PNM rate in this population is difficult to asses because it includes women with type 1 and type 2 diabetes and excludes some women with previously undiagnosed type 2 diabetes misdiagnosed as having GDM. There are only a few published reports on PNM in type 2 diabetes. Cundy et al7 reported a rate of 46 fetal deaths per 1000 pregnancies over a 12-year period, significantly higher than the 12.5/1000 reported for type 1 or the 8.9/1000 reported for GDM. Most of the increased mortality rate was explained by late fetal deaths related to maternal obesity, advanced age, hypertension and low socioeconomic class. However, as the study sample consisted mostly of native Maori women and immigrants from the Pacific Islands residing in New Zealand, the findings cannot be generalized to more heterogeneous populations. Other maternal comorbidities including obesity, higher maternal age, higher frequency of hypertension, and low socioeconomic class were also present in these women and probably contributed to the increased mortality rate. These women also presented for care later than women with type 1 disease and many were smokers. Many women with type 2 diabetes suffer from massive obesity, which has been associated with an increased risk of late fetal death, fetal macrosomia, and preterm delivery. Other studies reported a PNM rate ranging from 4/1000 to 81/1000. Some studies showed no significant difference in PNM between patients with type 2 and type 1 diabetes whereas one study reported four perinatal deaths in 113 patients with type 2 and none in 46 patients with type 1 disease17. Other neonatal outcomes were also examined in this study. There were no significant differences in the rates of macrosomia, cesarean section, shoulder dystocia, or neonatal hypoglycemia between mothers with type 1 and those with type 2 diabetes. If this finding is confirmed in other studies and if, in fact, the outcomes of women with type 2 diabetes are similar to those of women with type 1 diabetes, women with type 2 diabetes and their infants should receive similar concern to that shown to women with type 1 diabetes. Just as infants born of mothers with type 1 diabetes are at increased risk of congenital anomalies, so are the infants of women with type 2 diabetes. Major congenital anomalies affect 4-12% of infants of mothers with overt diabetes, a percentage that is 3to 5-fold greater than that in the offspring of nondiabetic mothers, and these anomalies are a leading cause of PNM in this population. Moreover, poorer attendance at prepregnancy care, later booking for prenatal care, and poorer glycemic control during organogenesis are thought to contribute to the higher rate of congenital malformations.