VERY-LOW MATERNAL SERUM CHORIONIC-GONADOTROPIN LEVELS IN ASSOCIATION WITH FETAL TRIPLOIDY

OBJECTIVE: The objective of this study was to identify the parental or igin of the extra haploid set of chromosomes in triploid pregnancies a nd to correlate the parental origin to very low levels of human chorio nic gonadotropin and unconjugated estriol levels (multiple of the medi an less than or equal to 0.20) and normal cr-fetoprotein levels. STUDY DESIGN: Three triploid pregnancies were ascertained retrospectively, and three pregnancies were identified prospectively. Maternal sera sam ples were analyzed for levels of alpha-fetoprotein, human chorionic go nadotropin, and unconjugated estriol. Deoxyribonucleic acid analysis w as performed on parental bloods and fetal fibroblasts in two prospecti vely identified pregnancies to establish the parental origin of the ex tra set of chromosomes. RESULTS: Levels of alpha-fetoprotein were norm al in all pregnancies. Levers of human chorionic gonadotropin were ver y low in five of six of pregnancies, and unconjugated estriol levels w ere low in three of six pregnancies. Deoxyribonucleic acid analysis in dicated maternal origin of the extra haploid set of chromosomes in two triploids. CONCLUSION: When the extra haploid set of chromosomes are maternally derived, some triploid pregnancies exhibit very low levels of maternal serum human chorionic gonadotropin and unconjugated estrio l with normal levels of alpha-fetoprotein.