Impact of prenatal glucose screening on the diagnosis of gestational diabetes and on pregnancy outcomes

The authors examined the impact of universal screening on the diagnosis of gestational diabetes and its complications. AII mothers and newborns regist ered by the Canadian Institute for Health Information from 1984 to 1996 (ev en-numbered fiscal years only) were included in the analysis. Over this tim e period, the proportion of women with gestational diabetes increased ninef old (from 0.3% to 2.7%) while the proportion with prepregnancy diabetes fel l from 0.7% to 0.4%. As rates of gestational diabetes increased, a correspo nding reduction in the risks of complications (polyhydramnios, amniotic cav ity infection, cesarean delivery, and preeclampsia) occurred for women with gestational diabetes. The incidence of gestational diabetes fell in Metro- Hamilton (where screening was discontinued in 1989) but remained high in th e rest of Ontario (where screening continued in most areas). No related tem poral trends for fetal macrosomia, cesarean delivery, or other diabetes-rel ated complications were observed, regardless of screening policy The author s concluded that the substantial increase in gestational diabetes in Canada is an artifact caused by universal screening, with no evidence of benefici al effects on pregnancy outcomes.