Currently invasive cytogenetic determination is the standard for ambiguous genitalia, X-linked conditions and single gene disorders such as congenital adrenal hyperplasia.
Chorionic villus sampling and amniocentesis have procedure related pregnancy loss.
Fetal sex determination can be performed by ultrasound as early as 11 weeks gestation, although not reliably.
Fetal sex determination by ultrasound is not successful in 7.5-50% of pregnancies at 11 weeks gestation, and the percentages falls to 3%-24% at 13 weeks (Odeh M et ).
Ultrasound fetal sex determination is incorrect as often as 40% of the time at 11 weeks, although by 13 weeks accuracy approaches 100%.
Noninvasive prenatal determination of fetal sex uses cell free fetal DNA to detect the presence of a Y-chromosome sequence performance was greatest using real time quantitative PCR after 20 weeks gestation.