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Prenatal multivitamins for undernourished women may reduce risk of low birth weight

January 02, 2007

Undernourished women who take a vitamin and mineral supplement while pregnant may be less likely than women taking only iron and folic acid supplements to have babies weighing less than 2,500 grams, and their newborns may be less likely to have morbidity in the first seven days of life, according to a report in the January issue of Archives of Pediatrics & Adolescent Medicine, one of the JAMA/Archives journals.

Low birth weight, or a weight of less than 2,500 grams, is a major predictor of death in infancy, according to background information in the article. It also increases the risk that the child will grow up to develop coronary heart disease, type 2 diabetes, stroke or high blood pressure. In countries low on resources, a mother's nutrition before and during pregnancy are known to affect the birth weight of her baby. Low-income women are often deficient in a number of micronutrients (vitamins and minerals), including vitamins C and E, vitamin B complex and folate.

Piyush Gupta, M.D., M.A.M.S., University College of Medical Sciences, Delhi, India, and colleagues conducted a randomized trial involving 200 women who were 24 to 32 weeks pregnant and either underweight (having a body mass index of less than 18.5) or with a low hemoglobin level (between 7 and 9 grams per deciliter), which can indicate malnourishment. The women all lived within 5 kilometers of a hospital in East Delhi, India, and planned to deliver either at the hospital or in the neighborhood. Information about the participants, including age, height and pre-pregnancy weight, was collected at the hospital between May 1, 2002, and April 30, 2003.

One hundred and one of the women were randomly assigned to take a placebo tablet containing only calcium, and the other 99 received a tablet containing a mix of 29 micronutrients and were instructed to take it daily. Both groups were given iron and folic acid supplements and guidance on prenatal health and were monitored during regular prenatal clinic visits. If the baby was born at the hospital, information about the delivery, birth weight and health of the child was collected there; otherwise, the mothers were contacted personally and asked for this information. Newborns at the hospital were followed up for seven days to detect any evidence of congenital abnormalities or other conditions or illnesses.

Women in the micronutrient group gained an average of 9.2 kilograms (20.3 pounds) during their pregnancies, compared with 8.7 kilograms (19.2 pounds) in the placebo group. Of the 200 babies born, 146 were included in the analysis of birth size and 170 (88 in the micronutrient group and 82 in the placebo group) in the analysis of death or illness within seven days. After the researchers adjusted for other factors that affect birth weight, babies whose mothers took micronutrients weighed an average of 98 grams more and were .8 centimeters longer. Rate of low birth weight was 43.1 percent in the placebo group vs. 15.2 percent among those on micronutrient supplements. Four infants died in each group.

"Our findings are of a preliminary nature and need to be further corroborated," the authors write. "We advocate community-based trials in deprived populations to ascertain the impact of a supplementation schedule lasting throughout pregnancy. The sample size should be large enough to evaluate the effect of such supplementation on neonatal morbidity and mortality, in addition to the size at birth."

JAMA and Archives Journals