mentation in a group of women who had the lowest 20 percent of seafood consumption at study entry (p<0.05), compared to a 2.8-day increase in gestation associated with fish-oil supplementation in all women.
The committee found that compared to women in Denmark and Norway, US women have been shown to consume less omega-3 long-chain polyunsaturated fatty acids and have lower levels of DHA in breast milk (Jensen et al., 1995). They also have, on average, shorter gestation durations and smaller infants (Smuts et al., 2003 a,b; Olsen et al., 1992; Helland et al., 2001). Birth weight depends on both length of gestation and intrauterine growth. Problematically high birth weight is not due to excessive gestation but rather to excessive intrauterine growth. No experimental trials have been conducted in the United States in which fish-oil supplements were evaluated for increasing gestation duration.
In a randomized controlled trial, Smuts et al. (2003b) evaluated the effect of feeding DHA-fortified eggs (mean 133 mg DHA/egg) to pregnant women in the United States, beginning at 24–28 weeks gestation. They reported a significant increase in gestation of 6 days among women consuming the high-DHA eggs compared to women receiving unfortified eggs (mean 33 mg DHA/egg). There was no significant increase in birth weight (p=0.184), birth length (p=0.061), or head circumference (p=0.081) among infants of mothers consuming high-DHA eggs. Although birth weight is frequently used as a marker for infant growth, head circumference and birth length are likely better indicators of positive pregnancy outcome.
An observational study examining an association between seafood consumption and gestational duration was conducted in a cohort of women in the Orkney Islands and Aberdeen, Scotland. This study identified a significant association between the 30 percent greater amount of seafood consumed by Orkney Island women over that consumed by women in Aberdeen, Scotland, and an increase in gestational duration of 2.5 days (p=0.01) (Harper et al., 1991).
Olsen et al. (1991) examined whether there was a difference in the ratio of the long-chain polyunsaturated fatty acids (LCPUFA) EPA, DPA, and DHA to arachidonic acid (AA) measured in erythrocytes obtained within 2 days of delivery between Faroese and mainland Danish women and whether there was a correlation between the LCPUFA levels and gestational duration in these populations. Among the Faroese subjects, significantly higher percentages of blood EPA and DHA were detected compared to Danish subjects, whereas DPA and AA values in both groups were similar. The Faroese subjects were found to have a gestational duration an average of 2 days longer (p=0.3) and a corresponding higher birth weight of 140 g