Abstract

Objective: To identify a polyunsaturated fatty acid (PUFA) biomarker able to detect which women with singleton pregnancies are most likely to benefit from omega-3 supplementation to reduce their risk of early preterm birth.

Design: Exploratory analysis of a randomised controlled trial.

Setting: Six Australian hospitals.

Population: Women with a singleton pregnancy enrolled in the ORIP trial.

Methods: Using maternal capillary whole blood collected ~14 weeks' gestation, the fatty acids in total blood lipids were quantified using gas chromatography. Interaction tests examined whether baseline PUFA status modified the effect of omega-3 supplementation on birth outcomes.

Main outcome measure: Early preterm birth (<34 weeks' gestation).

Results: A low total omega-3 PUFA status in early pregnancy was associated with a higher risk of early preterm birth. Among women with a total omega-3 status ≤4.1% of total fatty acids, omega-3 supplementation substantially reduced the risk of early preterm birth compared with control (0.73 versus 3.16%; relative risk = 0.23, 95% confidence interval [CI] 0.07-0.79). Conversely, women with higher total omega-3 status in early pregnancy were at lower risk of early preterm birth. Supplementing women with a baseline status above 4.9% increased early preterm birth (2.20 versus 0.97%; relative risk = 2.27, 95% CI 1.13-4.58).

Conclusions: Women with singleton pregnancies and low total omega-3 PUFA status early in pregnancy have an increased risk of early preterm birth and are most likely to benefit from omega-3 supplementation to reduce this risk. Women with higher total omega-3 status are at lower risk and additional omega-3 supplementation may increase their risk.

Tweetable abstract: Low total omega-3 fat status helps identify which women benefit from extra omega-3 to reduce early prematurity.