A re‐evaluation of the influence of maternal insulin‐dependent diabetes on fetal nuchal translucency thickness and first‐trimester maternal serum biochemical markers of aneuploidy

Abstract

To evaluate the influence of maternal insulin-dependent diabetes mellitus (IDDM) on maternal serum free ß-hCG, pregnancy-associated plasma protein-A (PAPP-A) and fetal nuchal translucency (NT) thickness from 11 weeks to 13 weeks 6 days of gestation in a large cohort of women screened prospectively for chromosomal anomalies. Information on maternal IDDM status, maternal serum biochemical marker levels and fetal NT were collected from the prenatal screening computer records. On total, the control group included 83,972 and the IDDM group included 489 pregnancies. The median-corrected free β-hCG and PAPP-A, expressed as MoM, and fetal NT, expressed as delta values, in the IDDM and non-IDDM groups were compared. There were no significant differences between the IDDM and non-IDDM groups in median-corrected free β-hCG (IDDM 1.01 MoM, non-IDDM 1.01 MoM; p = 0.970), or mean delta NT (IDDM 0.00 mm, non-IDDM 0.02 mm; p = 0.412). However, the median-corrected PAPP-A was significantly lower (IDDM 0.88 MoM, non-IDDM 1.03 MoM; p < 0.0001). In pregnancies with maternal IDDM, first-trimester screening for chromosomal defects does not require adjustments for the measured fetal NT and maternal serum free ß-hCG. However, for PAPP-A the 15% reduction is large enough to require correction in the calculation of risks for chromosomal defects.