Population studies indicate that dietary intake of docosahexaenoic acid (DHA) is associated with longer gestation, but the U.S. diet usually includes less than 100 mg per day of DHA. A pilot study of dietary supplementation using eggs with enhanced DHA content showed gains in duration of gestation and infant birth weight in U.S. women. Smuts and colleagues studied similar dietary supplementation in 347 women receiving prenatal care at an urban university medical center.

The patients enrolled in the study between weeks 24 and 28 of pregnancy, with gestation confirmed by ultrasonography. Those with singleton pregnancies and no contraindications to the study were randomly assigned to eat eggs enriched with DHA (mean: 133 mg of DHA per egg) or ordinary eggs (mean: 33 mg DHA per egg). All participants received 12 eggs per week. Participants were interviewed biweekly to monitor egg intake and followed until delivery.

Most of the mothers were black and received government assistance. The two study groups were equivalent in all significant variables. Complete data were available on 142 patients in the high-DHA group and 149 patients in the placebo group. No safety concerns were noted during the study. After controlling for significant variables, such as smoking, previous pregnancies, and maternal body mass index, the patients in the high-DHA group gained a significant six days of gestation. Infant birth weight increased by 103 g. Rates of preterm delivery, low birth weight, and other outcomes did not differ between groups.

The authors conclude that increasing DHA intake provided clinically significant gains in duration of gestation in a population of high-risk mothers.