Breast development in infants

Written by arleah difebbo
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Breast development in infants
Newborns are affected by their mother's hormones for several weeks after birth. (baby image by Yvonne Bogdanski from

They may be welcomed by pregnant women and expected by female teenagers, but breast development in babies is both surprising and nothing to worry about. Mothers and teens aren't the only ones affected by pesky hormones. For weeks after a baby is born, the hormones from his mother can cause breast buds.

Why It Happens

Pregnancy and hormones go hand in hand. After surging through a woman's body for nine months, some of those hormones get transferred to her baby. Heidi Murkoff, B.S.N., and author of "What to Expect: The First Year" says "Because of an infusion of female hormones from the placenta just before birth, many babies, boys and girls, have swollen breasts and/or genitals."

Size and Shape

Breasts can develop in male and female infants. The small buds are generally a half-inch in size and do feel firm, but should not appear red or feel warm when touched. The breasts can also have a milky discharge. However, Shanna R. Cox, M.D., warns, "If parents note the bud to be changing in size, or should it develop any surrounding redness, this should immediately be reported to the child's paediatrician. Bloody discharge should also be checked immediately. These symptoms may be indicative of an infection in the breast tissue, or of a clogged duct."


Entering parenthood comes with much unsolicited advice from family, friends and even strangers. While all of it is usually said with good intentions, each piece of advice should be taken with a grain of salt. This includes the idea that modern-day vitamins or hormones in food are the cause of breast development in infants.

In fact, breast development in babies has been documented for some time. According to Cox, "In the past (the milky) discharge was often referred to as 'witch's milk.' Many believed this to be an abnormal reaction that indicated 'possession' of the infant by a witch. Clearly this theory lost favour, along with many other superstitious beliefs, centuries ago."

Breasts in Toddlers

Breast development in infants is caused by the mother's hormones, but the appearance of breasts in toddlers is a different story. If you notice your 2-year-old or 3-year-old has enlarged breasts, she could have "premature thelarche." It usually only occurs in females.

Shari Nethersole, M.D., says "The cause is not entirely clear but in some girls there seems to be a slight increase in oestrogen production for a short period of time. The oestrogen is what causes the breast to sprout. In the vast majority of girls who have this, the breast bud will shrink down again over a period of several months, or if it doesn't become smaller, at least it won't continue to enlarge."

Time Frame

Hold off on buying a training bra or an extra-large T-shirt for your little newborn girl or boy. The breasts will eventually disappear, along with the cradle cap, infant acne, and other unfortunate side effects of being a newborn. It the breast buds and discharge haven't left in about a month, contact your child's paediatrician. Until then, don't sweat it, and know that it has happened to almost every baby, quite possibly since the beginning of time.

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