What Causes Vaginal Bleeding in Newborns?

Vaginal bleeding in newborn girls is a physiological phenomenon known as “pseudo-menstruation.” While in utero, newborns are continuously exposed to maternal estrogen. After delivery and umbilical cord clamping, this maternal estrogen supply is abruptly cut off, leading to a rapid decline in estrogen levels. As a result, newborn girls may exhibit vaginal bleeding resembling that seen during the menstrual cycle in adult women.

This typically occurs on days 5–7 after birth and may be accompanied by abundant non-purulent vaginal discharge, lasting approximately one week. If the bleeding is minimal, no specific treatment is required—simply change diapers or disposable diapers promptly and maintain perineal hygiene.

However, if the bleeding volume is substantial, a bleeding disorder should be considered. A common cause is vitamin K deficiency. In such cases, prompt referral to the neonatology department is recommended for comprehensive evaluation, timely diagnosis, and appropriate treatment.

For infants under six months of age, vaginal bleeding—provided no trauma is evident—may initially be observed. However, if bleeding persists beyond 24 hours, immediate medical evaluation is advised to determine the underlying cause and initiate timely treatment. Parents should always take great care in protecting their infants, especially when cleaning the genital area of baby girls—avoid excessive force or vigorous scrubbing.