Biochemical screening for chromosomal disorders and neural tube defects (NTD): is adjustment of maternal alpha-fetoprotein (AFP) still appropriate ininsulin-dependent diabetes mellitus (IDDM)?

Maternal serum alpha-fetoprotein (AFP) has been reported to be decreased in insulin-dependent diabetes mellitus (IDDM). The objective of the present s tudy was to reinvestigate this finding in detail. Maternal serum levels of AFP, human chorionic gonadotropin (hCG), and unconjugated estriol (uE3) in 114 diabetic women, of whom 84 had IDDM, were compared to those of 19,251 c ontrol pregnancies in the second trimester (15th to 20th gestational weeks) . The mean body weight at the date of sampling was 73.7 kg in all diabetic women, 72.7 kg in women with IDDM and 68.3 kg in non-diabetic women, respec tively. Body weights were significantly (p<0.001) elevated in all diabetic pregnancies. Using weight-adjusted MoM (multiple of the median) values no s tatistical difference of serum levels in diabetic and non-diabetic pregnant women was found. Median MoM levels were 1.01 (hCG), 1.01 (uE3), 1.06 (AFP) in all diabetic women, and 0.95 (hCG), 0.96 (uE3), 0.96 (AFP) in women wit h IDDM, respectively. Ignoring adjustment for maternal weight leads to a re duction of all serum parameters in diabetic pregnancies. However, median Mo M values of all three analytes are not statistically different when compare d to non-diabetic pregnancies. This finding is contrary to the results of f ormer studies from the 1970s and 1980s. It is concluded that progress in in sulin adjustment and blood glucose surveillance of diabetic patients on the whole has balanced out serum levels. Therefore adjustment of serum AFP val ues for diabetic status no longer seems reasonable. Copyright (C) 2001 John Wiley & Sons, Ltd.