MATERNAL SERUM SCHWANGERSCHAFTS PROTEIN-1 (SP1) AND FETAL CHROMOSOMAL-ABNORMALITIES AT 10-13 WEEKS GESTATION

Maternal serum SP1 concentration was measured at 10-13 weeks' gestatio n in samples from 87 pregnancies with fetal chromosomal abnormalities (trisomy 21 n = 45; trisomy 18 n = 19; trisomy 13 n = 8; Turner syndro me n = 7; 47,XXX or 47,XXY n = 4; triploidy n = 4), and in samples fro m 348 matched controls. In the control group, SP1 increased significan tly with fetal crown-rump length (r = 0.20, P < 0.0001) and there was no significant association with fetal nuchal translucency thickness (r = 0.03). similarly, in the group with fetal chromosomal abnormalities , SP1 increased significantly with crown-rump length (r = 0.31, P < 0. 01) and there was no significant association with nuchal translucency thickness (r = -0.08). In the groups with fetal trisomy 18 and trisomy 13, the median SP1 (0.76 MoM and 0.57 MoM, respectively) was signific antly lower than in the controls (z = 2.64 and z = 3.27, respectively) ; in 21% and 25% of the cases, values were below the 5th centile. In t he group with trisomy 21 and other chromosomal abnormalities the media n SP1 (0.96 MoM and 0.93 MoM, respectively) was not significantly diff erent from controls (z = 1.17 and z = 0.67, respectively). Measurement of SP1 concentration at 10-13 weeks' gestation is not likely to be us eful in the prediction of fetal chromosomal abnormalities.