Results of the recently published Omega-3 to Reduce the Incidence of Preterm Birth (ORIP) trial showed that supplementation with omega-3 long chain polyunsaturated fatty acids from 14 weeks of gestation until 34 weeks of gestation did not lower risk of early preterm delivery. The study included 5486 pregnant women which were randomized to receive either 900 mg of omega−3 long-chain polyunsaturated fatty acids or vegetable-oil capsules that contained trace n−3 long-chain polyunsaturated fatty acids (control) daily. In the omega-3 group, early preterm birth occurred in 61 case (2.2%) out of 2734, and in the control group it occurred in 55 cases (2%) out of 2752.
These results contradict other research, such as a Cochrane review which found that supplementation with omega-3s reduced the risk of preterm birth by 11% and early preterm birth by 42%. Another study published in the Journal of Nutrition found that omega-3 supplementation during the third trimester increased gestational age, size of gestational age, and the birth weight of infants.
While the ORIP trial did not find significant results and contradict previous findings, the researchers attribute the lack of significance to higher baseline omega-3 levels in subjects during the trial, which may have contributed to a lack of appreciable effect. Many women take perinatal supplements which contain small doses of DHA (less than 150 mg). According to an article from NUTRAingredients-asia.com, the researchers also interpret the results to mean that preventing preterm birth might be best achieved through targeted supplementation rather than a one-size-fits-all approach. Further investigation within the supplementation group found that women with initially low omega-3 levels did benefit from supplementation. Therefore, the researchers are now assessing the omega-3 levels of subjects and the levels needed to reduce preterm birth.