Expectant mothers may be able to prevent potentially serious medical problems in themselves and their babies simply by boosting their daily calcium intake, says a new systematic review. Not only that, but pregnant women at greatest risk for these problems may benefit most from the extra calcium.
The problems are gestational hypertension - or high blood pressure associated with pregnancy - and preeclampsia, a medical disorder of pregnant women characterized by high blood pressure and protein in the urine.
If untreated, both conditions can lead to potentially life-threatening medical problems for the mother and complications of preterm birth for the baby, including low birth weight and size, respiratory distress, long-term neurological deficits and even death.
"Pregnant women from communities with low dietary calcium who received at least 1.5 grams of calcium by mouth [daily] during the second half of pregnancy had a lower risk of hypertension and preeclampsia, and of severe complications including death, than women who received placebo treatment," said lead review author Dr. G.J. Hofmeyr.
The results were less dramatic for women with opportunities for better prenatal nutrition: "Women from communities with adequate dietary calcium had a small (10 percent) reduction in the risk of hypertension, but no significant reduction in the risk of preeclampsia or other adverse outcomes," said Hofmeyr, head of the obstetrics and gynecology department, East London Hospital Complex in South Africa.
The review appears in the current issue of The Cochrane Library, a publication of The Cochrane Collaboration, an international organization that evaluates medical research. Systematic reviews draw evidence-based conclusions about medical practice after considering both the content and quality of existing medical trials on a topic.
The authors looked at 12 randomized controlled studies, one involving more than 4,000 expectant moms in North America. The most recent and largest of the studies - conducted by the World Health Organization - involved more than 8,000 pregnant women internationally.
Preterm birth, or birth before 37 weeks, often stems from high blood pressure and is the leading cause of newborn deaths, particularly in low-income countries. A newly released report from the Institute of Medicine found that 12.5 percent of U.S. births are preterm and cost society an estimated $26 billion a year.
The Cochrane review found that calcium supplementation during pregnancy is a safe and relatively inexpensive way to reduce the risk of high blood pressure in women more likely to develop it, as well as in women from communities where consumption of dietary calcium is low.
"Calcium supplementation may be of some benefit in reducing the morbidity associated with preeclampsia, and it does no harm," said Dr. John T. Repke, chairman of obstetrics and gynecology at Penn State University College of Medicine.
"There is really almost nothing to lose from trying this approach, and based on this Cochrane Review, potentially something to be gained," added Repke, who has been conducting research on preeclampsia and related disorders for nearly 30 years.
In January 2002, the American College of Obstetricians and Gynecologists issued the following statement: "Daily calcium supplementation has not been shown to prevent preeclampsia and, therefore, is not recommended."