Associations between long chain omega-3s in pregnancy and obesity in young children
Donahue SMA, Rifas-Shiman SL, Gold DR, et al. Prenatal fatty acid status and child adiposity at age 3y: results from a US pregnancy cohort. Am J Clin Nutr , 2011; 93(4): 780-788.
This observational study looked at associations between EPA and DHA omega-3 and omega-6 fatty acids in women during pregnancy and adiposity (obesity) in their children at three years of age. Early influences on obesity are important because body composition evolves dramatically in early development and fat cell numbers established in early childhood remain stable throughout adulthood. The authors observed that higher intake of marine-source (long chain) omega-3s during pregnancy were associated with lower adiposity in early childhood. They also concluded that higher umbilical cord levels of omega 6:3 ratio were associated with higher adiposity.
This was a large study using mother-child pairs in the Project Viva observational cohort from eastern Massachusetts, USA. Dietary intake of long-chain fatty acids was measured at mid-pregnancy in more than 1100 mothers. Nutrient intakes were calculated from Food Frequency Questionnaires. Blood samples were taken from the mothers at mid-pregnancy, and also from the umbilical cord vein from the infants immediately after delivery. Obesity measures were made using well accepted markers, that is, body mass index (BMI), sub scapular, and triceps skinfold thickness. Obesity was defined at BMI greater than 95th percentile.
The mothers were an average of 32 years old and more than one-third were obese before pregnancy. Fish was the primary source of EPA and DHA. The mothers consumed on average 150 mg/day of combined EPA and DHA, well below current recommendations. Nearly 10% (9.4%) of the children were considered obese at age 3. Of interest, the percent of obese infants was equally distributed across all ages of pregnant women, but more children of women who were obese before pregnancy were measured as obese (22%). There was also more child obesity in children of women who used tobacco during their pregnancy.
The researchers concluded that the risk of obesity was about one-third lower in children at three years if maternal intake of EPA/DHA was higher (≥ 200mg per day). A higher ratio of omega 6:3 in umbilical cord blood correlated with increased risk of obesity. Because no significant association was found between omega-6 intake and child adiposity, the authors concluded that the association between the omega 6:3 ratio and adiposity was more likely due to low intakes of EPA and DHA.
Strengths of the Study
Large study population of mother-child pairs.
Long-chain fatty acids were measured in blood samples taken from the mothers at mid-pregnancy and children at birth (umbilical cord)
Obesity measurements were made using BMI and skin fold thickness (sub scapular and triceps).
Mothers who consumed fish oil supplements (including cod liver oil) were excluded from participating.
Weaknesses of the Study
Standard limitations with use of Food Frequency Questionnaires.
Standard reservations that occur with observational studies, such as potential influences of confounding factors.
Limitations of generalizing findings from this population to others around the world.
Relevance to Previous Studies
These study findings are consistent with the work of Helland et al (2008) who reported that cod liver oil supplementation during pregnancy until three months post-partum had no effect on BMI of the resultant children at seven years of age. These results are also similar to findings from a small intervention trial carried out by Bergman et al (2007); this study showed that children born of mothers who received 200 mg DHA per day through supplementation until the third month of lactation had lower BMI and weight (determined at 21 months of age) than infants in the placebo group.
Winwood R, Vannice GK, Weatherhead G, Cope M. Advances in EPA & DHA Research: Associations between long-chain omega-3s in pregnancy and obesity in young children. Quarterly Journal of Significant Omega-3 Research, 04;(02), 2011
Bergmann LR, Bergmann KE, Hascke-Becher E. et al. Does maternal docosahexaenoic acid supplementation during pregnancy and lactation lower BMI in late infancy? J Perinat Med, 2007; 35(4):295-300.
Helland IB, Smith L, Blomén B, et al. Effect of supplementing pregnant and lactating mothers with n-3 very-long-chain fatty acids on children's IQ and body mass index at 7 years of age. Pediatrics, 2008;122(2):e472-479.