BARCELONA -- Breast-feeding apparently is a strong antidepressant: Mothers who don't breast-feed at all during a baby's first year are almost twice as likely to be depressed as moms who have nursed, a researcher reported over the weekend.
And the outcome is not because women with better mental health are more likely to nurse, says psychologist Elizabeth Mezzacappa of Columbia College of Physicians and Surgeons in New York. She presented her findings at the American Psychosomatic Society meeting here.
''If a woman has pre-existing mental illness, this won't cure her, but for garden-variety moms, it can make a big difference,'' Mezzacappa says.
About one out of 10 U.S. women develop clinical depression within six weeks of their baby's birth, she says.
Using a large federal health survey, Mezzacappa looked at the link between mothers' mental health and nursing during the first year of their babies' lives. She then checked their depression levels three years after birth. The mothers filled out questionnaires and were interviewed on their symptoms of depression.
In the first survey, the 605 women who exclusively bottle-fed had almost twice the depression rate of the 378 mothers who had done some breast-feeding, even briefly.
But three years after childbirth, with findings available from 509 bottle-feeding and 333 nursing mothers, there was no difference in their depression levels.
Mezzacappa took into account key factors known to affect mental health, such as work and marital status, number of children, education and income level.
Breast-feeding appears to give new mothers a mood boost that disappears after the baby is weaned, she says. The most likely cause is oxytocin, a hormone released in nursing that is known to have an antidepressant effect, Mezzacappa says. Depressed people have low oxytocin levels, she adds.
This oxytocin-fueled mood lift probably evolved to promote survival of the species, Mezzacappa suggests.
''It's as though the baby has to do something to reward the mother for breast-feeding because in ancient times, babies died if their moms didn't bond with and nurse them,'' she says.
About seven out of 10 U.S. mothers start breast-feeding in the hospital, but only three in 10 are still doing it six months later, says Lawrence Gartner, an emeritus pediatrics professor at the University of Chicago Medical School and an expert on breast-feeding. The American Academy of Pediatrics advises at least 12 months of breast-feeding.
Recent trends are pro-breast-feeding, Gartner says. In 1970, only one out of four U.S. women even started at the hospital, and less than one in 20 still nursed when babies were 6 months old, he says.
''There's a learning curve here, and it does get easier over time. . . . About half of mothers need some help. But because breast-feeding became so unpopular, we lost several generations of knowledge. Many women breast-feeding now have never seen a woman do it,'' Gartner says.
Returning to work makes nursing harder, he adds. But some large corporations are providing breast pumps, as well as places and time for new moms to express milk so they can continue to nurse. Among the businesses Gartner named: Eastman-Kodak Co. and Cigna Corp.
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