Calcium supplementation is associated with a significant protective benefit in the prevention of pre-eclampsia, and should be used for this indication according to a previous review. This review indicates that there are no additional benefits for calcium supplementation in prevention of preterm birth or low infant birth weight. While there was a statistically significant difference of 80 g identified in mean infant birth weight, there was significant heterogeneity identified, and the clinical significance of this difference is uncertain.
Effects of dietary calcium intervention on adolescent mothers and newborns: A randomized controlled trial.
To evaluate the effects of dietary calcium (Ca) intervention on adolescent pregnant mothers and their newborns.
                Seventy-two pregnant adolescent mothers were randomized into one of 3 groups: control, orange juice fortified with calcium, and dairy. The orange juice and dairy groups were required to take more than 1,200 mg Ca. Calcium tablets were added for those not able to meet required Ca. Maternal and infant weight, length, and blood pressure (BP) were recorded. Maternal dietary records were evaluated. Mother's blood was drawn for serum Ca, phosphate (P), magnesium (Mg), and vitamin 25-hydroxyvitamin D (D). Cord blood was collected for serum Ca and D. Newborn total body Ca was determined.
                All mothers were similar in weight, height, and BP. Mothers in the orange juice plus calcium and dairy groups had higher intakes of Ca (1,472 mg and 1,771 mg) than controls (862 mg). One half of the mothers in the orange juice plus calcium group required Ca tablets. Mothers in the dairy group had higher intakes of P, D, and Mg, higher serum folate and D, and higher cord D levels. Mothers in the orange juice plus calcium group had higher serum P but lower serum folate and D. Infants (3,517+/-273 g) in the dairy group were heavier than infants in the control (3,277+/-177 g) and orange juice plus calcium (3,292+/-165 g) groups. Infants in the dairy group had higher total body calcium than control infants.
                Calcium diet supplemented with dairy products during adolescent pregnancy resulted in higher maternal vitamin D and folate serum levels and higher newborn weight and bone mineralization compared with controls.