Hormonal Effects in Newborns

Alternate Names : Normal Conditions in A Newborn Resulting from Maternal Hormones

What are the signs and symptoms of the condition?

The hormones that the fetus is exposed to in the several weeks prior to birth primarily affect the newborn's skin and genitals. For the first 6 to 8 weeks after birth, an infant will often have a rash on his or her face. This rash consists of small, red bumps and "whitehead" like pimples. For this reason, the condition is often referred to as "baby acne." This rash occurs most often on the forehead, cheeks and nose. It can also occur on the upper trunk.

Estrogen hormones from the mother's body cause breast tissue to enlarge in both boys and girls. This normally occurs late in pregnancy. Beginning at about the 36th week of pregnancy both infant girls and boys begin to develop "breast buds." This is the swelling of breast tissue immediately beneath and around the nipples. At birth these buds are usually about 1/2 to 3/4 inch in diameter and protrude about 1/4 inch. The nipple itself does not become enlarged. At times a small drop of a milk-like secretion may be seen on the infant's nipple. Breast buds may remain swollen for several weeks after birth in breastfed infants who continue to be exposed to these estrogen hormones.

Maternal hormones also affect the pigmentation of the newborn's skin. These hormones mainly affect skin areas that are sensitive to hormones, such as the nipples and genitals. At birth, this skin is darkly pigmented in both boys and girls. This is similar to the effects hormones will have on these areas in puberty. In addition, the hormone exposure in late pregnancy causes baby's genitals to enlarge. However, the size and color of the genitals returns to normal within a few weeks after birth.

Another condition caused from maternal hormones in some newborn girls is a slight, whitish mucous discharge from the vagina. This discharge is due to a temporary maturation of the mucous-secreting vaginal cells. It too goes away within a few weeks.

Maternal hormones can also affect newborn infants through a condition called "breast milk jaundice." Some mothers produce a hormone in their milk called pregnanediol. This hormone interferes with the liver's ability to metabolize or breakdown a substance called bilirubin. Bilirubin is a by-product of the breakdown of the hemoglobin in red blood cells. Normally, bilirubin is broken down in the liver so that it can be excreted in the urine. If bilirubin does not break down properly, it can accumulate in the blood and other tissues. This causes jaundice, which is a yellowish discoloration of the skin, urine and whites of the eyes. Unless there are other complicating factors, breast milk jaundice is not harmful to the baby. It usually goes away within several weeks. Interrupting breast-feeding for 24 to 48 hours often causes the jaundice to resolve more quickly. However, this is not necessary for the health of the baby.