Teenage girls who become pregnant may be at increased risk for weakened bones, researchers report.

In a new study, one third of teen mothers had low bone mass typical of the brittle-bone disease osteoporosis or a precursor condition called osteopenia.

The findings highlight the importance of adequate calcium intake during teenage pregnancy, the study’s lead author told Reuters Health.

“It is particularly important to insure that pregnant teens consume the recommended amount of calcium during pregnancy, 1,300 milligrams per day, to insure that sufficient calcium is absorbed to meet both maternal and fetal calcium demands,” said Dr. Kimberly O. O’Brien of the Johns Hopkins Bloomberg School of Public Health in Baltimore.

“Further research is needed,” she continued, “to determine if higher amounts of calcium than currently recommended can minimize maternal bone loss in this age group.”

Calcium is in high demand during pregnancy as the growing fetus needs the nutrient for bone formation. While the fetus needs calcium to develop healthy bones, so does the pregnant teen. In fact, girls form 40 percent of their bone mass during adolescence.

Even though more than half a million teens give birth in the U.S. each year, there is little information on how pregnancy affects the bones of young mothers.

O’Brien and her colleagues studied 23 pregnant girls ages 13.5 to 18.3 years. Fifteen of the girls were available for follow-up during the first couple of months after giving birth.

As is typical in adults during pregnancy, calcium absorption was higher during pregnancy than after delivery.

About one out of every three teen mothers showed signs of significant bone thinning after giving birth, the researchers report in the December issue of the American Journal of Clinical Nutrition.

Of the fifteen girls whose bone mass was measured 3 to 4 weeks after giving birth, two girls fit the criteria for the brittle-bone disease osteoporosis. Another three girls showed signs of osteopenia.

Not all pregnant girls are doomed to have weak bone, however. The study showed that a higher intake of calcium during pregnancy was directly related to improved calcium balance. This suggests that greater calcium consumption during pregnancy may protect against bone loss, according to the report.

O’Brien and her colleagues conclude that more research is needed to evaluate the long-term effect of teen pregnancy on the formation of peak bone mass.

More here.