Speaking of interesting articles by ACOG this month- they published one that showed increased intake of fish decreases risk of preterm birth in patients who have experienced preterm birth before. They found that 2-3 servings per week of fish particularly early in pregnancy had the greatest benefit, and that eating more than that did not show any extra benefit. However eating fish less than once a month for patients with increased preterm birth risk increased their risk of preterm birth again.
It is unknown if taking fish oil capsules has the same effect as eating fish. In this particular study, the patients who were given capsules started them at 16-21 weeks gestation and this did not decrease their risk for preterm delivery. Thus, it is either important to start them earlier in the first trimester or perhaps prior to pregnancy or to stick with fish as there may be some other dietary supplement in fish that decreases the risk of preterm labor/birth.
The study did not look at other socioeconomic factors, but as I tell all of my patients, 2 servings of fish/week is reasonable and may have added benefit of reducing preterm labor.