DHA supplementation and pregnancy outcomes.

Randomized, double-blind, placebo-controlled trial in pregnant women from the Kansas City metropolitan area. Eligibility included singleton pregnancy, English-speaking status, age 16 to 35.99 years, and enrollment at 8 to 20 weeks of gestation; women with multiple gestation, major medical illness, preexisting diabetes, systolic blood pressure at least 140 mm Hg, or BMI at least 40 were excluded. For the DHA arm, 178 participants were randomized and 154 had birth data available for analysis.

Pregnant participants in the active arm received 600 mg/day DHA as 3 oral capsules per day, each containing 200 mg DHA from marine algae oil (DHASCO; DSM Nutritional Products). Supplementation started at enrollment during 8 to 20 weeks of gestation and continued until birth, with placebo used as the comparator.

DHA supplementation improved maternal and infant DHA status and was associated with better birth outcomes. Maternal RBC-phospholipid DHA at birth was higher than placebo by 2.6% (P < 0.001), and cord RBC-phospholipid DHA was higher as well (P = 0.001). DHA increased infant size measures, including head circumference (P = 0.012), birth weight (P = 0.004), and birth length (P = 0.022), and reduced very early preterm birth: gestation <34 weeks was 0.6% vs 4.8% with placebo (P = 0.025) and birth weight <1500 g was 0.0% vs 3.4% (P = 0.026). Overall preterm birth was 7.8% vs 8.8%, and no safety concerns were identified for mother or infant.

The birth-outcome analysis included fewer participants than were randomized in the DHA arm (154 of 178), which can reduce precision. The trial was conducted in a single metropolitan area, so generalizability may be limited. Some outcomes were rare, so estimates for very preterm birth and very low birth weight are based on small event numbers.