Prenatal Nutritional Strategies to Reduce the Risk of Preterm Birth
Ann Nutr Metab 2020;76(suppl 3):31-39 DOI: 10.1159/000509901
Karen Patricia Best3, b Judith Gomersall3, c Maria Makrides3, b
- a Women and Kids Theme, South Australian Health and Medical Research Institute, Adelaide, SA, Australia;
- b School of Medicine, University of Adelaide, Adelaide, SA, Australia;
- c School of Public Health, University of Adelaide, Adelaide, SA, Australia
Preterm and Early Preterm vs weeks of pregnancy
Key Messages
- Cost-effective primary prevention strategies to reduce preterm birth (PTB) are required to reduce the ~15 million preterm babies born every year worldwide. Nutritional interventions may offer a promising solution.
- The strongest evidence to date for a nutritional solution to reduce PTB exists for omega-3 long-chain polyunsaturated fatty acids and suggests that women with low levels of omega-3 in early pregnancy may benefit from supplementation.
- Recent findings suggest that determining an individual woman's polyunsaturated fatty acid status in early pregnancy may be a precise way to inform recommendations to reduce her risk of PTB.
Worldwide, around 15 million preterm babies are born annually, and despite intensive research, the specific mechanisms triggering preterm birth (PTB) remain unclear. Cost-effective primary prevention strategies to reduce PTB are required, and nutritional interventions offer a promising alternative. Nutrients contribute to a variety of mechanisms that are potentially important to preterm delivery, such as infection, inflammation, oxidative stress, and muscle contractility. Several observational studies have explored the association between dietary nutrients and/or dietary patterns and PTB, often with contrasting results. Randomized trial evidence on the effects of supplementation with zinc, multiple micronutrients (iron and folic acid), and vitamin D is promising; however, results are inconsistent, and many studies are not adequately powered for outcomes of PTB. Large-scale clinical trials with PTB as the primary outcome are needed before any firm conclusions can be drawn for these nutrients.
The strongest evidence to date for a nutritional solution exists for omega-3 long-chain polyunsaturated fatty acids (LCPUFAs), key nutrients in fish. In 2018, a Cochrane Review (including 70 studies) showed that prenatal supplementation with omega-3 LCPUFAs reduced the risk of PTB and early PTB (EPTB) compared with no omega-3 supplementation. However, the largest trial of omega-3 supplementation in pregnancy, the Omega-3 to Reduce the Incidence of Prematurity (ORIP) trial (n = 5,544), showed no reduction in EPTB and a reduction in PTB only in a prespecified analysis of singleton pregnancies.
Exploratory analyses from the ORIP trial found that women with low baseline total omega-3 status were at higher risk of EPTB, and that this risk was substantially reduced with omega-3 supplementation. In contrast, women with replete or high baseline total omega-3 status were already at low risk of EPTB and additional omega-3 supplementation increased the risk of EPTB compared to control. These findings suggest that determining an individual woman's PUFA status may be the most precise way to inform recommendations to reduce her risk of PTB.
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