Preconception exposures and adverse pregnancy, birth and postpartum outcomes: Umbrella review of systematic reviews.

Michael Daly,Ruth R Kipping,Laura E Tinner,Julia Sanders,James W White

doi:10.1111/ppe.12855

Michael Daly, Ruth R Kipping + Show 3 more

Open Access

https://doi.org/10.1111/ppe.12855

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Abstract

Preconception exposures have been associated with adverse pregnancy, birth and postpartum outcomes. However, the reports, statements and guidelines of national and international health organisations vary in what they recommend individuals should monitor, avoid, reduce or practise in the preconception period. To synthesise and evaluate the evidence across systematic reviews for associations between exposures before conception and adverse pregnancy, birth and postpartum outcomes. MEDLINE, Embase, Epistemonikos (to May 2020) and reference lists of included reviews, without language or date restrictions. Systematic literature reviews of observational and/or interventional studies reporting associations between preconception exposures in women and/or men of reproductive age and pregnancy, birth or postpartum health outcomes were included. The methodological quality of reviews and the certainty of the evidence underlying each exposure-outcome association were assessed using AMSTAR 2 and the GRADE approach. We identified 53 eligible reviews reporting 205 unique exposure-outcome associations. Methodological quality was generally low with only two reviews rated as 'high' quality and two as 'moderate'. We found high-certainty, randomised trial evidence that maternal folate supplementation reduces the risk of neural tube defects and anomaly-related terminations. Moderate-certainty, observational evidence was found that maternal physical activity is associated with reduced risk of pre-eclampsia and gestational diabetes, and that paternal age of ≥40years and maternal body mass index (BMI) and interpregnancy weight gain are associated with increased risk of various adverse pregnancy and birth outcomes. Low- and very low-certainty evidence was found for other associations. Clinicians and policymakers can be confident that maternal folate supplementation should be encouraged during the preconception period. There is moderate certainty in the evidence base that maternal physical activity, BMI and interpregnancy weight gain and advanced paternal age are important preconception considerations. High-quality research is required to better understand other exposure-outcome associations.

Highlights

Preconception exposures have been associated with adverse pregnancy, birth and postpartum outcomes
While many systematic reviews reporting associations between preconception exposures and adverse pregnancy, birth and postpartum outcomes may exist, these are likely to vary in their scope and quality, and may present conflicting findings.[11]
Study question What is the certainty of the evidence across systematic reviews for associations between preconception exposures and adverse pregnancy, birth and postpartum outcomes?

Summary

Introduction

Preconception exposures have been associated with adverse pregnancy, birth and postpartum outcomes. There are around 23 million miscarriages,1 14.8 million live preterm births,[2 295,000] neonatal deaths due to congenital anomalies[3] and 295,000 maternal deaths due to pregnancy or childbirth complications each year.[4] Social, demographic, environmental and biomedical exposures before conception have been associated with these outcomes as well as longer-term offspring health and developmental outcomes.5-7 a recent review by Schoenaker et al.[8] found that the clinical guidelines, position statements and policy reports of national and international health organisations vary in the preconception exposures they name as being important Many of these guidelines, statements and reports fail to define the criteria used to determine exposure eligibility or evaluate the quality and strength of the evidence supporting the associations of these exposures with adverse outcomes. While a systematic review by Rumbold et al concluded that maternal periconception vitamin supplementation does not affect the risk of stillbirth,[12] a later systematic review reported an association between this exposure and reduced stillbirth risk.[13]

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