Preterm birth is the leading cause of child mortality worldwide

If asked to name the leading cause of child mortality, you’d probably guess infectious disease, or pneumonia, or something equally formidable. What you probably wouldn’t guess is being born too early. But you’d be wrong. 

Preterm birth, defined as birth before 37 weeks of pregnancy, is now the leading cause of child mortality worldwide, and currently on the rise in the United States.¹ According to the latest national birth statistics, one in ten babies in the United States are born preterm or early preterm (before 34 weeks), which is markedly higher than rates in other developed countries.^2,3

In addition to heightened mortality, these babies are at a higher risk of long-term complications, including visual impairment, developmental delay, and learning difficulties.⁴ As such, evidence-based methods for remediating visual, neurological, and developmental delays in children born prior to full-term need to be developed.

Supplementation with DHA during pregnancy may reduce the chances of delivering early

According to growing literature, one such method for safeguarding the developmental outcomes of children born preterm is supplementation with docosahexaenoic acid (DHA), a polyunsaturated fatty acid with specific structural and functional roles in the brain and body.⁵ Notably, the literature has already established that supplementation with omega-3 DHA during pregnancy can reduce a woman’s chances of  delivering too early; however, the focus of this article will be on how supplemental DHA can support the developmental outcomes of babies born before 37 weeks.^6–8

A developing baby receives DHA from the mother via placental transfer

DHA is widely believed to play an instrumental role in babies’ prenatal and postnatal development—particularly during periods of rapid brain and retinal development in the third trimester and first few years of postnatal life.⁵ A developing baby receives DHA from the mother via placental transfer throughout pregnancy, but especially during the third trimester. In fact, during the last few weeks of pregnancy (from weeks 35 to 40), DHA accumulation increases as much as 840% in skeletal muscle, the brain, the liver, and adipose tissue (fat)!^9,10 Consequently, children born during this period of concentrated DHA accumulation do not obtain the same amount of DHA as babies delivered full-term.

After birth, a nursing baby will continue to receive DHA from its mother’s breastmilk. Unfortunately, many American women of child-bearing age do not receive sufficient DHA through diet alone, which can affect the levels in their breastmilk, and ultimately, the amount of DHA their babies receive.¹¹ Because humans are unable to synthesize adequate DHA for themselves, and thus must rely on outside sources, it is recommended that non-breastfed children be given a formula enriched with DHA.¹²

However, whether or not children born prematurely should be provided with especially high doses of DHA—either through maternal supplementation or direct supplementation—has been a topic of debate for some time. Let’s look at the research.

DHA is especially important for premature infants

Evidence that babies born early benefit uniquely from DHA supplementation comes from a study comparing the neurodevelopmental outcomes of children from two large-scale intervention trials.¹³ In the first trial (the DHA to Optimise Mother Infant Outcome, or DOMInO trial), researchers compared the effects of DHA supplementation during pregnancy on children’s later mental development by randomly assigning women to take either 3000 mg of DHA per day or a placebo from mid-pregnancy through birth, and then testing their children’s mental developmental at 18 months.¹⁴ (Please note that children in the placebo group still received DHA via maternal transfer—but markedly less than children in the high-DHA group.) 

In the second trial (the DHA for the Improvement of Neurodevelopmental Outcome, or DINO trial), infants born before 33 weeks’ gestation were randomly assigned to either a standard-DHA group, or a high-DHA group that received three times as much DHA as the standard group (0.9% vs 0.3% of total fatty acids).¹⁵ Similar to the DOMInO trial, children in the DINO trial were tested on a mental developmental index (MDI) at 18 months. After comparing the MDI scores of high-DHA and standard-DHA children in each trial, the researchers found that cognitive differences were more pronounced between groups in the DINO trial, suggesting that DHA supplementation was more effective in supporting the neurodevelopmental outcomes of preterm children than full-term infants. 

However, it is worth noting that significant reductions in the proportion of children with delayed cognitive development were evidenced in the high-DHA groups of both trials. That is, regardless of whether they were preterm of full-term, children receiving high- DHA went on to show significantly fewer cognitive delays than children receiving standard DHA levels.^14,15 And importantly, this effect was more noticeable in preterm children, where the proportion of children with severe cognitive delay was cut in half relative to the standard-DHA children.¹⁵

Further evidence that babies born prior to full term may be in particular need of DHA yields from a study showing that mothers of preterm babies produced breastmilk with significantly higher concentrations of DHA than mothers of full-term babies. This study compared the fatty acid composition of milk from mothers of infants born before 37 weeks and mothers of infants born 40 weeks or later and found that DHA levels were twice as high in the milk of mothers with children born early.¹⁶

While it would be overly-speculative to attribute these findings to an evolutionary mechanism where the body compensates for the lack of maternal DHA transfer in late pregnancy with higher DHA concentrations in the breastmilk, the idea that a mother’s body allocates a certain amount of DHA for fetal transfer—and works to transfer it however possible—underscores the importance of DHA for normal development. Moreover, that the fatty acid composition of breastmilk for preterm babies was twice as high as that of milk produced for full-term children suggests that children born early would likely benefit from higher concentrations of DHA. 

High-dose DHA supplementation may help decrease neurodevelopmental delays in preterm children

Given the increasing rate of babies delivered prior to term in this country (and globally), finding effective strategies for remediating the developmental consequences of being born too early are necessary. Research studies examining the effects of high-dose DHA supplementation on the incidence of neurodevelopmental delays in preterm children indicate that DHA may be one such effective strategy. If you are a parent to one of the 10% of American children born prematurely every year, we strongly encourage you to speak to your child’s doctor about whether DHA supplementation can help.