Health Encyclopedia

Hormonal effects in newborns

Definition

While in the womb, a baby is exposed to many chemicals (hormones) present in the mother's blood stream. After birth, the infants are no longer exposed to these hormones. This may cause temporary conditions in a newborn.

Alternative Names

Newborn breast swelling; Physiologic leukorrhea

Information

Hormones from the mother (maternal hormones) are some of the chemicals that pass through the placenta during pregnancy. They affect the baby.

For example, during pregnancy high levels of the hormone estrogen are produced. This causes breast enlargement in the mother. It can have a similar affect in newborn boys and girls by the third day after birth. Such newborn breast swelling is temporary, but is a common concern among new parents. The breast swelling should go away by the second week after birth as the hormones leaves from the newborn's body. Do not squeeze or massage the newborn's breasts because this can cause an infection under the skin (abscess).

Maternal hormones may also cause some fluid to leak from the infant's nipples. This is called witch's milk. It is common and usually goes away within 2 weeks.

Newborn girls may also have temporary changes in the vaginal area.

The skin tissue around the vaginal area, called the labia, may look puffy as a result of the estrogen exposure.
There may be a white fluid (discharge) from the vagina. This is called physiologic leukorrhea.
There may also be a small amount of bleeding from the vagina.

These changes are common and should slowly go away over the first 2 months of life.

Review Date:3/14/2009
Reviewed By:Neil K. Kaneshiro, MD, MHA, Clinical Assistant Professor of Pediatrics, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

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