Abstract
The placenta is a vital, multi-functional organ that acts as an interface between maternal and fetal circulation during pregnancy. Nutritional deficiencies during pregnancy alter placental development and function, leading to adverse pregnancy outcomes, such as pre-eclampsia, infants with small for gestational age and low birthweight, preterm birth, stillbirths and maternal mortality. Maternal nutritional supplementation may help to mitigate the risks, but the evidence base is difficult to navigate. The primary purpose of this umbrella review is to map the evidence on the effects of maternal nutritional supplements and dietary interventions on pregnancy outcomes related to placental disorders and maternal mortality. A systematic search was performed on seven electronic databases, the PROSPERO register and references lists of identified papers. The results were screened in a three-stage process based on title, abstract and full-text by two independent reviewers. Randomized controlled trial meta-analyses on the efficacy of maternal nutritional supplements or dietary interventions were included. There were 91 meta-analyses included, covering 23 types of supplements and three types of dietary interventions. We found evidence that supports supplementary vitamin D and/or calcium, omega-3, multiple micronutrients, lipid-based nutrients, and balanced protein energy in reducing the risks of adverse maternal and fetal health outcomes. However, these findings are limited by poor quality of evidence. Nutrient combinations show promise and support a paradigm shift to maternal dietary balance, rather than single micronutrient deficiencies, to improve maternal and fetal health. The review is registered at PROSPERO (CRD42020160887).
Highlights
Sustainable Development Goal 2 aims to eradicate world hunger by 2030; the 2020 State of Food Security and Nutrition in the World report indicated that 8.9% of people in the world are undernourished, which has impacts on both maternal and fetal well-being [1]
124 records were excluded at full-text review, including a mismatch in populations in a single study, three in intervention, three in comparator, 12, which did not report outcomes of interest, 19 in study design and 48 duplicates and older versions of Cochrane reviews (Table S3)
The purpose of the umbrella review was to evaluate the current evidence on the effect of nutritional supplements and dietary interventions on PE, small for gestational age (SGA), low birthweight (LBW), preterm births (PTB), stillbirth and maternal death
Summary
Sustainable Development Goal 2 aims to eradicate world hunger by 2030; the 2020 State of Food Security and Nutrition in the World report indicated that 8.9% of people in the world are undernourished, which has impacts on both maternal and fetal well-being [1]. Maternal undernutrition is known to have important impacts on fetal development and early infancy as the sole source of nutrients for a growing infant from conception through exclusive breastfeeding [2]. Maternal undernutrition alters placental development and function, leading to fetal growth restriction [4]. Studies of the impact of severe maternal undernutrition during the Dutch Famine during the winter of 1944–1945 found associations between placental weight and rates of LBW, preterm births (PTB), stillbirths and neonatal death [5,6]. The failure of the proper development of the placenta is associated with pre-eclampsia (PE), the most serious of the hypertensive disorders of pregnancy (HDP) and the second leading direct cause of maternal mortality worldwide [7,8,9]. Nutrition plays an important role in placentation in part due to the clinical antioxidant and anti-inflammatory properties of certain micronutrients [10]
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