One-quarter of pregnant US women not meeting recommended omega-3 intake

Omega-3 polyunsaturated fatty acids (PUFAs) are essential nutrients and studies have shown that they – particularly docosahexaenoic acid (DHA) – contribute to foetal and early life neurodevelopment as well as improving pregnancy outcomes, including a reduced risk for preterm birth.

Generally, pregnant and breastfeeding women are advised to consume at least 500 mg a day of long-chain omega-3 PUFAs, including 200 mg/day of DHA, for health, a recommendation based on data from a large number of observational studies and some randomised trials. The 2020-2025 US Dietary Guidelines also recommend that pregnant and breastfeeding women eat between 8 and 12 ounces (around 225 to 340 grams) per week of low-mercury seafood sources.

A study, however, has shown that many women in the US may be failing to meet these amounts. Publishing their findings in the journal Public Health Nutrition, researchers from the Harvard Pilgrim Health Care Institute used data from cohorts across the US participating in the Environmental influences on Child Health Outcomes (ECHO) programme. The data included information on fish consumption reported by 10,800 pregnant women and supplement intake information from 12,646 pregnant women.

Women who would benefit the most are least likely to supplement

The researchers found that 24.6% of women said they ate fish never or less than once a month; 40% did so less than once a week; 22% once or twice a week; and 13% more than twice a week. Women who ate less fish were also less likely to take omega-3 supplements, putting them at increased risk for insufficient intake of omega-3 fatty acids.

Additionally, the scientists found that supplement use was less common among women who had a higher risk of experiencing adverse pregnancy outcomes due to smoking, use of nicotine products, or having a higher body mass index (BMI). In other words, women who may benefit the most were less likely to take omega-3 supplements, according to the researchers.

Fish intake and supplement use were higher among older women and those with a higher income and education level. Women over the age of 40 were about twice as likely to use supplements as those under 29.

“Omega-3 fatty acids are essential nutrients for supporting positive health outcomes,” said lead author Emily Oken, Harvard Medical School professor and chair of the department of population medicine at the Harvard Pilgrim Health Care Institute. “Getting enough of these nutrients during pregnancy is vital for preventing preterm birth and promoting optimal child health and neurodevelopment.”

She added: “Our study provides updated information to inform much needed public health advice and resources to support clinical conversations to encourage consumption of low-mercury fish during pregnancy and intake of omega-3 supplements among those who do not consume fish.”

Eating fish is better than taking omega-3 supplements

According to the study, the scientific community tends to agree that the best way to meet recommendations for adequate omega-3 PUFA intake is by eating fish, partly because “experimental evidence has not supported offspring developmental benefits of supplementation”. However, for those who cannot or choose not to eat fish, omega-3 PUFA supplements are recommended, they added.

“Ongoing effective public health advice and resources to support clinicians are needed to encourage consumption of low-mercury fish during pregnancy and intake of omega-3 supplements among those who do not consume fish,” concluded the authors.

Although the study was based on a large sample size and included recent data from the two decades leading up to 2020, the authors noted they were limited by their inability to assess specific fish types and the fact that information on dietary intake was self-reported and therefore may be unreliable.

Additionally, the ECHO population may not necessarily be nationally representative as the participants chose to take part in the cohorts and therefore may be more health-conscious than the general population, they added.