Accuracy of fetal gender determination in maternal plasma at 5 and 6 weeks of pregnancy

Objective To assess the viability of the early diagnosis of fetal gender in maternal plasma before 7 weeks of pregnancy by real‐time polymerase chain reaction (real‐time PCR), starting at 5 weeks of pregnancy. Method Peripheral blood was collected from pregnant women, starting at 5 weeks of gestation. After centrifugation, plasma was separated for fetal DNA extraction. DNA was analyzed by quantitative real‐time PCR for two genomic regions, one on the Y chromosome (DYS‐14) and the other shared by both sexes (ß‐globin), by the TaqMan Minor Groove Binder (MGB) probe assay. The results of the examinations were compared to fetal gender determined after delivery. Results A total of 79 examinations of fetal DNA in maternal plasma were performed for 52 pregnant women. Accuracy according to gestational age was 92.6% (25 of 27 cases) at 5 weeks, and 95.6% (22 of 23 cases) at 6 weeks. These results also demonstrate that fetal DNA is present at low concentrations in maternal plasma at 5 weeks (8.5 genome equivalents (GE)/mL) and 6 weeks (34.1 GE/mL) of pregnancy. Conclusion Quantitative real‐time PCR and TaqMan MGB probes specific for the detection of fetal gender in maternal plasma starting at 5 weeks of gestation have good sensitivity and excellent specificity. Copyright © 2006 John Wiley & Sons, Ltd.