Down syndrome screening is a method that detects the concentration of alpha-fetoprotein and human chrionic gonadotropin (HCG) hormone(chorionic gonadotropin) in maternal serum, and combines the due date, age, weight, and gestational age at the time of blood collection to calculate the risk coefficient of giving birth to a Down syndrome child.
Genital bleeding in children could be due to delayed menstruation caused by breastfeeding, or other reasons, and should be checked by a doctor promptly.