As most people could guess, hormones during pregnancy prepare the breasts for nursing. Jabara said that mothers who adopt babies and wish to breast-feed can mimic this process by taking hormones, particularly prolactin.
Experts explain that a woman in Nancy Beattie's position, who gave birth to children years ago, could potentially breast-feed simply by using a breast pump and simulating the motion of nursing.
"It's easier to turn on the faucet, so to speak, after having a child," said Dr. Jane Morton, a clinical professor of pediatrics at Stanford University in Palo Alto, Calif.
Morton explained that the hormones in pregnancy permanently change the breast tissue to prepare it for breast feeding. After a pregnancy, the breasts stay "mature" forever.
If a woman isn't pregnant, Morton said, "it's a slow process to gradually increase your production," but it is possible. The key to getting milk to flow from mature breast tissue, either moments after childbirth or years later, is to stimulate the nipple.
"You have a nerve connection from the nipple that goes all the way to another part of the brain that produces oxytocin," said Jabara.
"Even if you have all the right conditions, if the baby doesn't stimulate the nipple, you won't have milking," he said.
Pregnancy and the stimulation of nipples may be nature's way of starting lactation, but Jabara notes there are various other conditions that can set off lactation, even in men.
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