Effects on birth weight and perinatal mortality of maternal dietary supplements in rural Gambia: 5 year randomised controlled trial.

Abstract

Objective: To test the efficacy in terms of birth weight and infant survival of a diet supplement programme in pregnant African women through a primary healthcare system. Design: 5 year controlled trial of all pregnant women in 28 villages randomised to daily supplementation with high energy groundnut biscuits (4.3MJ/day) for about 20 weeks before delivery (intervention) or after delivery (control). Setting. Rural Gambia. Subjects: Chronically undernourished women (twin bearers excluded), yielding 2047 singleton live births and 35 stillbirths. Main outcome measures: Birth weight; prevalence of low birth weight ([is less than] 2500 g); head circumference; birth length; gestational age; prevalence of stillbirths; neonatal and postneonatal mortality. Results: Supplementation increased weight gain in pregnancy and significantly increased birth weight, particularly during the nutritionally debilitating hungry season (June to October). Weight gain increased by 201 g (P [is less than] 0.001) in the hungry season, by 94 g (P [is less than] 0.01) in the harvest season (November to May), and by 136 g (P [is less than] 0.001) over the whole year. The odds ratio for low birthweight babies in supplemented women was 0.61 (95% confidence interval 0.47 to 0.79, P [is less than] 0.001). Head circumference was significantly increased (P [is less than] 0.01), but by only 3.1 mm. Birth length and duration of gestation were not affected. Supplementation significantly reduced perinatal mortality: the odds ratio was 0.47 (0.23 to 0.99, P [is less than] 0.05) for stillbirths and 0.54 (0.35 to 0.85, P [is less than] 0.01) for all deaths in first week of life. Mortality after 7 days was unaffected. Conclusion: Prenatal dietary supplementation reduced retardation in intrauterine growth when effectively targeted at genuinely at-risk mothers. This was associated with a substantial reduction in the prevalence of stillbirths and in early neonatal mortality. The intervention can be successfully delivered through a primary healthcare system.

Introduction

Low birth weight is a major contributor to neonatal and postneonatal mortality. Twenty five million babies a year are born below 2500 g, the World Health Organisation's cut off point for low birth weight and over 90% of these are born in developing countries where perinatal and infant mortality is already high.[1]

Considerable controversy still remains about whether dietary supplementation in pregnancy can increase birth weight. Some authors argue that the case at best is unproved.[2 3] Kramer performed a metaanalysis that showed only modest increases in maternal weight gain and fetal growth.[4] Others have shown that when data are disaggregated certain subgroups of women do benefit,[5-10] though Kramer's meta-analysis failed to find evidence that undernourished women benefited more than those who were adequately nourished.[4] Interpretation is often hampered by inadequate experimental design.[2]

We reported a highly significant beneficial effect of supplementation in a trial involving 379 rural Gambian women.[6 11] This trial was criticised, and was not entered in Kramer's analysis because it used historical controls (a condition imposed by an ethics committee). Additionally, the supplement was complex and expensive, and its distribution and consumption were carried out under intensive experimental conditions.

In the present study we tested the efficacy of a cheaper dietary supplement provided under realistic field conditions through the primary healthcare system in the Gambia. We report results from a 5 year prospective randomised controlled trial in 28 rural villages, with birth weight and infant survival as the primary outcome measures.

Methods

Design

The study was conducted among rural, subsistence-farming …