Taking fish oil supplements during pregnancy won't boost baby's brain or prevent postpartum depression for mom, researchers found.
Overall cognitive scores were nearly identical and language scores tended to be lower in children exposed to docosahexaenoic acid (DHA)-rich fish oil during gestation than scores in controls, according to researcher Maria Makrides of the Women's and Children's Hospital in Adelaide, Australia.
As for the new mothers, there was no significant difference in the prevalence of depressive symptoms in the first six months postpartum between women who took the fish oil pills and those who didn't, the investigators reported in the Oct. 20 issue of the Journal of the American Medical Association.
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Many pregnant women have turned to such supplements to meet recommendations for daily intake of 200 mg/d DHA, a critical nutrient for neurodevelopment for which fish is the main dietary source.
Although epidemiologic evidence points to lower postpartum depression risk and better neurodevelopment with dietary consumption of fish in pregnancy, the evidence for fish oil supplements has been less than unanimous and limited by methodological issues, Makrides and colleagues noted.
The discrepancy might reflect residual confounding in the observational studies, or it may just be that eating fish is better than taking a supplement, commented Dr. Emily Oken of Harvard and Dr. Mandy B. Belfort of Children's Hospital Boston in an accompanying editorial.
"It may be that the n-3 polyunsaturated fatty acids in fish are more bioactive or that other beneficial nutrients within fish, such as selenium, vitamin D, and iodine, are also important," they wrote in JAMA.
Longer-term follow-up of children in the study is needed to see if advantages from extra DHA exposure show up in the school years, the editorialists noted.
Makrides' group argued that their results don't support routine DHA supplementation for pregnant women.
But Oken and Belfort recommended that, for now, women should continue to aim for the recommended daily intake of DHA through low-mercury, high-DHA fish intake or supplements.
Makrides' group used a higher than recommended dose -- 800 mg a day of DHA with 100 mg eicosapentaenoic acid -- in their DOMInO (DHA to Optimize Mother Infant Outcome) study.
The researchers cautioned that their study didn't include dietary analysis of DHA or high levels of eicosapentaenoic acid, which has been controversial for ratio to DHA in perinatal supplements.
The study included 2,399 women with singleton pregnancies of less than 21 weeks' gestation seen at five Australian maternity hospitals randomized to double-blind treatment with capsules containing DHA or vegetable oil as a placebo up until the time of birth.
The maternal primary endpoint turned up a nonsignificant 15 percent lower risk of high levels of depressive symptoms in mothers as indicated by a score of more than 12 on the Edinburgh Postnatal Depression Scale at six months postpartum.
This might deserve further study, although it's possible that just being in the study resulted in the lower than expected rate of depressive symptoms, which weren't confirmed with clinical diagnosis, the researchers noted.
Among the infants, the primary endpoint of development scores on the Bayley Scales of Infant and Toddler Development at 18 months showed that those whose mothers took the fish oil supplement didn't score better for composite cognition or composite language compared with children in the control group.
For the secondary developmental outcomes, DHA exposure in utero appeared to have no impact on motor development, social-emotional behavior, or adaptive behavior at 18 months.
DHA did appear to have an effect on duration of gestation, though, consistent with prior studies.
The DOMInO trial showed the greatest impact of DHA at the extremes, with fewer very preterm births before 34 weeks gestation but also more post-term births requiring obstetric intervention.
The editorialists pointed to the reduction in preterm birth as a noteworthy result despite the small number of these events.
"Preterm birth is a serious and thus far intractable public health problem that is the leading cause of neonatal death in the U.S," they wrote, noting that tocolysis is of limited effectiveness and no preventive strategy is appropriate for the general population.