Pregnant adolescents who don’t eat enough dairy may be competing with their growing babies for calcium, according to recent research (American Journal of Clinical Nutrition, 2003, vol. 77, no. 5). Researchers at Johns Hopkins Bloomberg School of Public Health analyzed the diets of 350 African Americans who were 17 years old or younger and under the care of a Baltimore maternity clinic between 1990 and 2000. The pregnant teens were given a sonogram at 20 to 34 weeks to measure fetal femur bone length, an indicator of fetal bone development.

The women were sorted into three groups: “adequate” calcium intake (four or more 300-mg servings per day), “fair” intake (two to three servings per day), and “poor” intake (zero to one servings per day). Results showed that more than 75 percent of the adolescents consumed inadequate amounts of calcium. Teens who ate less than two dairy servings per day had the lowest fetal femur length among all subjects.

Lead researcher Kimberly O’Brien, PhD, says the study looked specifically at African-American adolescents because “this group is frequently understudied yet is at higher risk of early childbearing.” Also, according to O’Brien, African-American teens generally have lower calcium intakes than Caucasian teens.

The National Institute of Child Health and Human Development reports that nearly 85 percent of all females age 12 to 19 do not meet the RDA for calcium. The deficiency becomes a bigger threat when a teen is pregnant. “Teens that become pregnant during the key period of bone acquisition need to be especially vigilant with respect to calcium intake to ensure that they fully mineralize the skeleton of their developing fetus,” says O’Brien, “and to ensure that there is also adequate calcium available for them to achieve peak bone mass.” According to the National Academy of Sciences, adequate calcium intake for pregnant teens is 1,300 mg daily.