Article Text
Abstract
Objectives To assess the relation between five common occupational exposures (working hours, shift work, lifting, standing, workload) and five adverse outcomes of pregnancy (pre-term delivery (PTD), low birthweight, small for gestational age (SGA), pre-eclampsia, gestational hypertension).
Methods We conducted a search in MEDLINE and EMBASE (1966–2011) using combinations of keywords and MeSH terms. Reports were assessed for their reporting and potential for bias and confounding. Meta-estimates of relative risk (RR) were produced where possible. The material comprised 86 reports (57 reports with usable data on PTD, 54 on birthweight and 11 on pre-eclampsia/gestational hypertension).
Results For PTD, findings across a large evidence base were consistent in ruling out large effects (e.g. RR>1.2). Larger and better quality studies were even less positive (RR 1.04 to 1.18). For SGA, the position was similar but meta-estimates were close to the null. For pre-eclampsia/gestational hypertension the evidence base was insufficient to draw strong conclusions.
Conclusions The balance of evidence is not compelling enough to justify mandatory restrictions on any of the activities considered in this review. Over time, estimates of risk for these activities and outcomes have become smaller.