What you need to know:

There is evidence that dietary intervention during pregnancy can increase the size of the baby at birth. Interventions providing food and fortified food products or targeting pregnant women who are underweight, nutritionally at-risk or from a low income country are the most promising strategies to increase the size of the baby at birth. However, size is just a surrogate marker for other health and economic outcomes. Further large high-quality randomised controlled trials investigating combination dietary intervention and micronutrient provision from food are needed. Future trials spanning preconception, the duration of pregnancy and even between pregnancies are needed to advance our understanding of optimal maternal nutrition for maternal-child health.


What this research is about:

Nutrition before conception and during pregnancy is important to ensure a healthy pregnancy outcome. Research has demonstrated the importance of diet as a prevention strategy for some adverse neonatal outcomes, particularly the role of folic acid for the prevention of neural tube defects. However, there is a clear need to identify the best dietary interventions for pregnant women aimed at preventing adverse neonatal and infant outcomes. The aim of this study was to synthesise the best of the available evidence by conducting a systematic review and meta-analysis to determine whether dietary interventions before or during pregnancy have any effect on neonatal or infant outcomes.

What did the researchers do:

A systematic review was conducted without date restrictions. Randomised controlled trials evaluating whole diet or dietary components and pregnancy outcomes were included. Two authors independently identified articles for inclusion and assessed methodological quality. Meta-analysis was conducted separately for each outcome using random effects models. Results were reported by type of dietary intervention: (i) counselling, (ii) food and fortified food products, or (iii) combination (counselling + food); and collectively for all dietary interventions. Results were further grouped by trimester when the intervention commenced, nutrient of interest, country income and body mass index.

What did the research find:

Of the 2326 abstracts screened, a total of 29 randomised controlled trials (31 publications) were included in this review, which included 10,026 participants. Results indicate that food or fortified food products increase birth weight (by approximately 125g) and reduce the incidence of low birth weight (by approximately 27% decrease in odds). Combining all dietary interventions, both increase birth weight and reduce the incidence of low birth weight (62g and 24% decreased odds respectively), and increase length (0.07cm). In sub-group analyses the largest gains in birth size are made in underweight and nutritionally at-risk populations, in both high and low income countries, and dietary interventions that focus on macronutrients.

How can you use this research:

This review advances our understanding of the role of nutrition for a healthy birth outcome. Providing nutrition education as well as food or fortified food products to pregnant women, particularly those who are underweight, at nutritional risk, or come from a low income country, is likely to increase the size of the baby at birth with important health and financial ramifications.

Contact person: Ellie Gresham ellie.gresham@uon.edu.au

Citation: Gresham, E., Byles, J.E., Bisquera, A., & Hure, A.J. The effects of dietary interventions on neonatal and infant outcomes: a systematic review and meta-analysis. American Journal of Clinical Nutrition. 2014.

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