Strict glycemic control in diabetic pregnancy-implications for second-trimester screening for Down syndrome

OBJECTIVES: Studies in the early 1990s showed that the normal levels of the biochemical markers used to screen for Down syndrome in the second trimester of pregnancy differ between healthy women and women with insulin-dependent diabetes mellitus (IDDM). Thereafter, most laboratories adopted correcting factors to adjust for these differences. However, the current validity of these factors in light of the recent improvements in glycemic control in diabetic pregnancy has not been investigated. METHODS: The sample consisted of 35 pregnant women with strictly controlled IDDM and 40 healthy controls matched for age and gestational week. All women had singleton pregnancies and were followed till delivery. RESULTS: Comparison of the triple test results between the two groups after adjustment with the traditional corrective factors yielded no significant differences in serum levels of any of the markers (unconjugated estriol, human chorionic gonadotrophin, alpha-fetoprotein). CONCLUSIONS: These results suggest that the recent improvement in glycemic control of pregnant women with IDDM changes the metabolic milieu that might cause the biochemical differences with healthy pregnant patients.