The cause of bleeding from the lower body of a newborn baby girl is mainly due to a physiological phenomenon. The physiological phenomenon is mainly caused by the fact that the newborn baby girl is subjected to significant fluctuations in the mother’s hormone levels after birth. Because the newborn is in the mother’s womb, the hormone levels in the body are greatly influenced by the mother’s hormone levels. The disconnection of hormone levels with the mother’s hormone levels after birth can cause the newborn baby girl’s hormone levels to fluctuate dramatically, which can lead to bleeding from the lower body. This is a normal physiological phenomenon, and as the newborn gets older, the bleeding will subside significantly. If the bleeding does not stop, the baby should be seen by a neonatologist.