Second-trimester maternal serum analyte levels associated with fetal trisomy 13.

The aim of this study was to determine whether pregnancies affected by fetal trisomy 13 are associated with second-trimester maternal serum analyte levels different from those typical of the unaffected population. Pregnancies with trisomy 13 were identified through cytogenetics laboratories. Those which had second-trimester maternal serum screening analyte measurements were further evaluated. Maternal serum analyte levels for each case and five matched controls were statistically analysed by matched ranked-sum analysis. 28 cases of fetal trisomy 13 were identified. The median AFP, uE3 and hCG levels were 1.35 MoM, 0.71 MoM and 0.90 MoM, respectively. Only uE3 levels were statistically different (p < 0.01) from those for the unaffected population. These data suggest that second-trimester maternal serum AFP, uE3 and hCG levels are not useful in detecting fetal trisomy 13 and protocols already existing for Down syndrome or trisomy 18 screening will not detect the majority of cases of this aneuploidy.