Omega-3s don't reduce pregnancy complications

June 14, 2012

Taking fish-oil supplements late in pregnancy has little actual effect on reducing gestational diabetes mellitus or preeclampsia. » More

Rates of gestational diabetes and preeclampsia were only slightly affected by DHA supplementation in the second half of pregnancy.

Rates of macrosomia were higher in women who took DHA-enriched fish-oil capsules, but rates of low birth weight and neonatal convulsions and death were lower than for controls.

Contrary to previous reports, fish-oil supplementation in the second half of pregnancy does not lower rates of gestational diabetes mellitus (GDM) or preeclampsia, according to a new double-blind, multicenter trial from Australia.

The trial, known as the DHA to Optimize Mother Infant Outcome (DOMInO) trial, involved 2,399 women from 5 perinatal centers who were randomized to receive either 800 mg per day docosahexaenoic acid (DHA)-enriched fish-oil capsules or capsules containing a blend of 3 vegetable oils without DHA.

These women took the capsules from the time they entered the study, which was prior to 21 weeks’ gestation, until they gave birth. Recruited between October 2005 and January 2008, all of the women were pregnant with singleton pregnancies; 39% were primiparous.

Published in the American Journal of Clinical Nutrition (2012;95[6]:1378-1384), the results of the study reveal an overall incidence of 8% and 5%, respectively, of GDM and preeclampsia. Although the women who took the fish-oil capsules had a 3% lower risk of GDM and a 13% lower risk of preeclampsia than controls taking the vegetable oil capsules, the differences were not statistically significant.

The rate of macrosomia was higher in the DHA group than in controls; however, the percentage of women requiring antenatal hospitalization did not differ between the groups. Neither did glycemic response, bone fracture, or pregnancy complications. However, rates of low birth weight, neonatal death, and neonatal convulsion were lower in the DHA group than in controls.

The authors concluded that although fish-oil supplementation in the second half of pregnancy does not seem to lower rates of GDM or preeclampsia, its use in reducing rates of perinatal death and neonatal convulsions deserves further investigation.

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