Maternal serum alpha-fetoprotein and epithelial tumour marker concentrations are not increased by fetal sacrococcygeal teratoma.

Maternal serum alpha-fetoprotein (AFP) and total beta-human chorionic gonadotrophin (hCG) concentrations were measured at the 15th gestational week in ten pregnancies complicated by fetal sacrococcygeal teratoma. The findings corresponded to those in normal pregnancies. Similarly, third-trimester concentrations of cancer antigen 12-5, tumour-associated trypsin inhibitor, and the amino-terminal propeptide of type III procollagen in the maternal serum were not significantly elevated. Histologically mature and immature/malignant cases did not differ from each other as regards the above-mentioned parameters. This abnormality cannot be detected by maternal serum trisomy screening in the second trimester.