Omega-3 supplements in pregnancy for leaner kids?

11th May 2024, A/Prof Chee L Khoo

Omega-3 supplements?

I recall reading somewhere that increasing fish intake during pregnancy results in leaner offsprings. It all makes sense as we know that ω-3 fatty acid (ω-3 FA) is beneficial for adults (also read somewhere). It must be good for babies then. Is there data on those claims? Well, sort of. We shall look into them. And the more fish oils, the better? Well, what about fish oil supplements rather than fish intake. It’s faster and easier, isn’t it? If more is better, taking lots via supplements must be good? Maybe, maybe not.

There have been suggestions that there may be an association between the ratio of ω-6/ω-3 fatty acid and adipose tissue development during the critical early phases of life. There is evidence to suggest that ω-3 FA have anti-obesity effects by decreasing lipid synthesis in cells. Well, it is then reasonable to suggest that maternal intake of ω-3 FA during pregnancy might help to reduce susceptibility to obesity later in life.

The results to date are rather conflicting. Wood K et al. supplemented women in the second half of pregnancy with ω-3 FA (high-DHA tuna oil (800 mg/day DHA)), chiefly as DHA and looked at percentage body fat of children at 7 years of age (1). There were also no differences in height, weight or waist and hip circumference between the DHA and placebo groups at 7 years of age.

Middleton, P, et al conducted a Cochrane to assess the effects of ω-3 FA, as supplements or as dietary additions, during pregnancy on maternal, perinatal, and neonatal outcomes and longer-term outcomes for mother and child (2). The effect of ω-3 FA on body mass index at 19 years (1 trial, 243 participants; very low‐quality evidence) was uncertain.

When Mariam Vahdaninia et al conducted a systematic review and meta-analysis in 2018 to look into the potential role of ω-3 FA supplementation during pregnancy on subsequent risk of obesity outcomes in the offspring, they found that maternal supplementation with ω-3 FA during pregnancy does not have a beneficial effect on obesity risk. They did comment that there was heterogeneity in the studies and the studies had small sample size and high attrition rates.

Vinding R et al examined the effect of supplementation with ω-3 FA in pregnancy on anthropometry and body composition in offspring. 736 pregnant women and their offspring were given either fish oil or olive oil (placebo) from week 24 of pregnancy. Fish oil supplementation from the 24th week of pregnancy led to a higher BMI in the offspring from 0 to 6 years of age but not an increased risk of obesity at age 6. The body composition at age 6 years in children given fish oil supplementation was characterised by a proportional increase in lean, bone, and fat mass suggesting a general growth stimulating effect of n ω-3 FA.

Vinding R et al recently presented their findings after 10 years of follow-up. Children of mothers receiving ω-3 FA supplementation had increased BMI at age 10 y, increased risk of being overweight, and a tendency of increased fat percentage and higher metabolic syndrome score.

Interestingly, the ω-3 FA supplementation was not associated with blood lipids, blood glucose, waist circumference, or blood pressure when analysed independently, although all the estimates were in the direction of an unhealthier metabolism among children in the ω-3 FA group. Further, the effect estimates of the ω-3 FA supplementation on BMI, weight, waist circumference, fat percentage, and metabolic syndrome score were higher in children born by mothers with maternal BMI <25 compared to the children born by mothers with BMI >25.

In summary, data on the offspring benefits of omega 3 FA supplementation in pregnant women is still unclear. The latest long (10 year) follow up on children whose mother had ω-3 FA supplements suggest that there may be harm in these children. Naturally, we need more studies and await further updates as these 10 year old grow past their puberty years.


  1. K. Wood, E. Mantzioris, B. Lingwood, J. Couper, M. Makrides, R.A. Gibson, et al. The effect of maternal DHA supplementation on body fat mass in children at 7 years: follow-up of the DOMInO randomized controlled trial Prostaglandins Leukot. Essent. Fatty Acids., 139 (2018)
  2. P. Middleton, J.C. Gomersall, J.F. Gould, E. Shepherd, S.F. Olsen, M. Makrides Omega-3 fatty acid addition during pregnancy Cochrane Database Syst. Rev., 11 (11) (2018)
  3. M. Vahdaninia, H. Mackenzie, T. Dean, S. Helps The effectiveness of ω-3 polyunsaturated fatty acid interventions during pregnancy on obesity measures in the offspring: an up-to-date systematic review and meta-analysis Eur. J Nutr., 58 (7) (2019)
  4. R.K. Vinding, J. Stokholm, A. Sevelsted, T. Sejersen, B.L. Chawes, K. Bønnelykke, et al. Effect of fish oil supplementation in pregnancy on bone, lean, and fat mass at six years: randomised clinical trial BMJ, 362 (2018)
  5. Vinding R et al. Fish oil supplementation during pregnancy, anthropometrics, and metabolic health at age ten: A randomized clinical trial The American Journal of Clinical Nutrition, Volume 119, Issue 4, April 2024