Maternal Blood Test Can Tell Parents Fetus’s Sex After 7 Weeks

Blood tests that isolate fetal DNA from a mother’s blood to detect gender work after seven weeks of gestation and are better than ultrasound at ruling out some genetic abnormalities, according to a report.

Ultrasound and urine tests are unreliable at determining fetal gender at that stage of development, according to a review of studies in the Journal of the American Medical Association. Amniocentesis, which involves using a needle to remove and test amniotic fluid, carries a risk of miscarriage and can’t be used until at least 15 weeks, after the end of the first trimester.