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Fish Oil Consumption May Prevent Pre-Term Birth

Low consumption of fish oils appears a strong risk factor for pre-term delivery and low birth weight.

A study among 8,729 pregnant Danish women indicates that long chain omega n.3 fatty acids in amounts above 2 g a day may delay spontaneous delivery and prevent recurrence of pre-term delivery, declares Dr Sjurour Frooi Olsen and colleagues at the Maternal Nutrition Group, Danish Epidemiology Science Centre, Statens Serum Institut, Copenhagen, Denmark.

The clinicians note that in an earlier study a findings of high birth weights and long gestations in the fish eating community of the Faroe Islands suggested that intake of seafood rich in long chain omega n.3 fatty acids can increase birth weight by prolonging gestation or by increasing the fetal growth rate.

Randomised controlled trials have shown that fish oil can delay spontaneous delivery and prevent recurrence of pre-term delivery, but the minimum amount of omega n.3 fatty acids needed to obtain this effect remains to be determined.

In their prospective cohort study, Dr Olsen found that the occurrence of pre-term delivery differed significantly across four groups of seafood intake by the women. This fell progressively from 7.1 percent in the group never consuming fish, to 1.9 percent in the group consuming fish as a hot meal and an open sandwich with fish at least once a week.

Adjusted odds for pre-term delivery were increased by a factor of 3.6 in the zero consumption group compared with the highest consumption group. Analyses based on quantified intakes indicated that the working range of the dose response is mainly from zero intake up to a daily intake of 15 g fish, or 0.15 g of omega 3 fatty acids.

Estimates of risk for low birth weight were similar to those for pre-term delivery.

Several observational studies have found associations between measures of maternal seafood intake and fetal growth rate.

Possible explanations are that the effects could be from consumption of omega n.3 fatty acids exerted before 16-20 weeks gestation, or by effects of other substances in seafood.

Dr Olsen and colleagues conclude: "Our study could substantiate neither of these two possibilities, as the associations between seafood consumption in early pregnancy and fetal growth rate tended to disappear after adjustment for potential confounders.

"Randomised controlled trials to examine the dose response relations between long chain n.3 fatty acids and timing of delivery and pre-term risk are warranted."
BMJ 2002;324:447-450. "Low consumption of seafood in early pregnancy as a risk factor for preterm delivery: prospective cohort study"

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