Omega-3s for better pregnancies

Pregnancies are difficult and risky in general, but complications can be devastating and fatal. For example, preterm birth, which is defined as an infant born before 37 weeks of gestation, accounts for more than 85% of perinatal complications^[1] and deaths in newborns. It is also the leading cause of death^[2] in children under the age of five, accounting for nearly 17% of all child deaths.

Although advances in neonatal care have reduced mortality rates, children who are born preterm also experience developmental issues^[3] and are also at higher risk for several conditions such as respiratory distress syndrome, necrotising enterocolitis, blindness, and cerebral palsy.

Adding to the possibility of such complications during pregnancy is the risk of depression, the most common mood disorder correlated with childbirth. A 2005 systematic review^[4] suggests that nearly 20% of women experience depression within three months of giving birth. Postnatal depression is also associated with poor childhood development outcomes.

Interventions that can reduce such complications are highly sought after. Prior research has shown that omega-3 fatty acids hold much promise. In the late 1980s^[5] and into the 1990s, health researchers noticed that certain populations who consumed diets high in fish had better pregnancy outcomes. However, many of these studies were observational and may have suffered from selection bias and confounding. While there are complex statistical^[6] and graphical^[7] methods to help address these problems, it is still difficult to conclude a causal relationship from such data, so randomized controlled trials (RCTs) were necessary to investigate the link.

As you can see in Figure 1’s timeline, a Cochrane review^[8] of six RCTs from 2006 concluded that there still was not enough evidence to recommend omega-3 fatty acid supplementation for pregnancy outcomes. Six years later, a systematic review of 15 RCTs^[9] found a small benefit on preterm birth. However, a 2015 systematic review^[10] of nine RCTs failed to find a significant difference, along with a 2016 systematic review^[11] of 95 RCTs and 48 observational studies by the U.S. Agency for Healthcare Research and Quality.

The study under review sought to review all of the current published and unpublished clinical trials, update the 2006 Cochrane analysis, and determine the effects of omega-3 interventions on preterm birth and several other pregnancy outcomes.

Preterm birth along with other pregnancy complications are responsible for a notable proportion of child deaths. Early observational research showed that populations that consumed fish also had better pregnancy outcomes. However, systematic reviews of randomized trials in the past decade failed to show any statistically significant effects on outcomes like preterm birth. The study under review looked at all the published and unpublished studies to date to assess the overall effect of fish oil on various pregnancy outcomes including preterm birth.