Omega-3 supplements during pregnancy are a standard prescription for prenatal care. Researchers have long acknowledged the benefits of DHA and EPA, two specific omega-3 fatty acids that are critical to the healthy development of fetal brains. But a new study is suggesting the benefits of fish oil supplements during pregnancy last not only through the nine months in the womb, but through the first six years of a kid’s life.

Previous research had linked fish oil supplements during pregnancy to higher birth weight, a major metric of a newborn’s health. But whether that marker of good health at birth lasts, or whether it turns into a negative (say, steady higher weight due to fat accumulation) for kids, has been unknown.

Researchers from Denmark and the UK have now found that children of women who took prenatal fish oil supplements had a greater BMI than children of mothers who had taken olive oil supplements during pregnancy. Overall, these former children had greater bone, lean and fat mass, all proportionate to healthy growth; increased BMI did not signal an increased risk of childhood obesity, but rather increases in bone and lean mass.

“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,” rather than merely a weight stimulating effect, the researchers say.

Researchers only studied the long-term effects on kids of fish oil supplements during pregnancy; omega-3 supplements can also be derived from plant sources, like flax. However, other research has shown that DHA and EPA derived from plant life is not as beneficial for fetal development as omega-3s derived from fish.

That’s not to suggest pregnant women should turn into voracious pescatarians during pregnancy in order to set kids up for healthy development; other research has suggested the benefits of consuming fish and/or fish oil during pregnancy taper off after a certain level of consumption. But the takeaway here is: omega-3s derived from fish, taken during pregnancy, don’t just make for a healthier newborn, but for a healthier 6-year-old as well.