Prenatal Vitamins for Malnourished Moms Improve Birth Weight

DELHI, India, Jan. 3 -- Prenatal vitamin and mineral supplements may benefit babies born to undernourished pregnant women, researchers here have found.

Among 200 pregnant women in a resource-poor area, micronutrient supplements reduced the rate of low birth weight by 70% and early neonatal morbidity by 58%, said Piyush Gupta, M.D., M.A.M.S., of the University College of Medical Sciences here, and colleagues.

Although the primary study endpoint of mean birth weight was not significantly affected by multivitamin supplements, reducing the incidence of low birth weight (under 2,500 g) may improve later health, the researchers said in the January issue of the Archives of Pediatrics & Adolescent Medicine.

"Infants who are small or disproportionate in size at birth also have an increased risk of developing coronary heart disease, type 2 diabetes mellitus, stroke, and hypertension during adult life," they wrote. "It is postulated that these diseases are programmed by inadequate supply of nutrients to the developing fetuses."

Previous trials of vitamins for pregnant women in developing countries have not targeted undernourished pregnant women, who are at greater risk for delivering undersize infants.

So, the researchers randomized 200 women who had a low body mass index (18.5 or less) or anemia (hemoglobin count 7 to 9 g/dL) to once-daily supplements containing 29 vitamins and minerals or to receive placebo containing only calcium. Both groups also received iron and folic acid supplements.

The double-blind study was conducted at a tertiary care hospital that serves poor residents from nearby urban slums and rural communities. Only women who lived within three miles of the hospital were enrolled. They were all given routine antenatal and dietary advice, immunization, and health education.

The women averaged about seven to eight weeks of treatment before delivery, with 87% and 85% compliance in the micronutrient and placebo groups, respectively.

The low birth weight incidence was 16.2% in the supplement group versus 43.1% in the control group (relative risk 0.30, 95% CI 0.13 to 0.71, P=0.006).

Neonatal morbidity during the first week of life was also significantly less common among infants in the micronutrient group (14.8% versus 28.0%, RR 0.42, 95% CI 0.19 to 0.94, P=0.04).

After adjusting for confounding factors, infants in the micronutrient group weighed 98 grams more (about 0.22 pounds, 95% confidence interval -?16 to 213 g) and were 0.8 centimeters longer (about 0.31 inches, 95% CI 0.03 to 1.57 cm) compared with infants in the control group. Mid arm circumference was also larger by 0.20 cm (about 0.80 inches, 95% CI 0.04 to 0.36 cm).

Pregnancy weight gain was no different between groups (9.2 versus 8.7 kg, P=0.26) nor was mean gestational age at delivery (39.6 versus 39.6 weeks, P=0.9) in the micronutrient and placebo groups, respectively.

The proportion born small for gestational age, though, was 55% lower in the micronutrient group (31.1% versus 51.4%, adjusted RR 0.61 0.45, 95% CI 0.21 to 0.97, P=0.04). Only one infant in each group was born preterm (gestational age less than 37 weeks).

Birth weight correlated very strongly with neonatal morbidity in the multivariate model and eliminated the group effect (P<0.001). Mortality was similar between groups (RR 0.93, 95% CI 0.24 to 3.61, P=0.92) as were causes of death.

Delivery details were available for 170 cases. Delivery complications among the 170 cases with details available occurred at a similar rate between groups (15% micronutrient versus 12% placebo P=0.66).

About 27% of women dropped out of the study and those who did were significantly more likely to have a lower family income (P<0.001) though no other baseline factors differed between these women and the overall groups.

Adverse effects of the intervention were no more common among women in the supplement group than in the control group (seven versus 13). They included nausea, vomiting, diarrhea, abdominal pain, and anorexia, but none required discontinuation.

The multimicronutrient supplement used in the study contained all 15 micronutrients suggested by the WHO and United Nations Children's Fund for pregnant women as well as the FDA recommended daily intake of 14 other nutrients.

However, it was an "unconventional formulation," commented Rachel A. Haws, M.H.S., and Gary L. Darmstadt, M.D., M.S., both of Johns Hopkins in Baltimore, in an accompanying editorial. This and other design flaws limited generalizability as did the targeted population studied, they said.

"Design flaws (e.g., restricted outcome assessment, inadequate sample size, insufficient duration/timing of nutrient exposure) and questionable severity of deficiencies in tested populations have precluded a clear evidence base to support widespread antenatal multiple-micronutrient supplementation at this time."

Furthermore, it was given only during the last trimester of pregnancy due to logistic constraints," they added. "Duration of supplementation (regression coefficient 9.24, P<0.001) and compliance (regression coefficient 12.35, P=0.001) both were significantly correlated with birth size, so supplementation throughout the pregnancy would be expected to have a greater effect.

Further studies will need to evaluate the impact of longer duration supplementation as well as to corroborate the findings, the researchers said.