A modular systematic review of antenatal interventions targeting modifiable environmental exposures in improving low birth weight

Background: Low birth weight (LBW) increases the risk of short- and long-term morbidity and mortality from early life to adulthood. Despite research effort to improve birth outcomes the progress has been slow. Objective: This systematic search and review of English language scientific literature on clinical trials aimed to compare the efficacy antenatal interventions to reduce environmental exposures including a reduction of toxins exposure, and improving sanitation, hygiene, and health-seeking behaviors, which target pregnant women to improve birth outcomes. Methods: We performed eight systematic searches in MEDLINE (OvidSP), Embase (OvidSP), Cochrane Database of Systematic Reviews (Wiley Cochrane Library), Cochrane Central Register of Controlled Trials (Wiley Cochrane Library), CINAHL Complete (EbscoHOST) between 17March 2020 and 26 May 2020. Results: Four documents identified describe interventions to reduce indoor air pollution: two randomised controlled trials (RCTs), one systematic review and meta-analysis (SRMA) on preventative antihelminth treatment and one RCT on antenatal counselling against unnecessary caesarean section. Based on the published literature, interventions to reduce indoor air pollution (LBW: RR: 0.90 [0.56, 1.44], PTB: OR: 2.37 [1.11, 5.07]) or preventative antihelminth treatment (LBW: RR: 1.00 [0.79, 1.27], PTB: RR: 0.88 [0.43, 1.78]) are not likely to reduce the risk of LBW or Preterm birth (PTB). Data is insufficient on antenatal counselling against caesarian-sections. For other interventions, there is lack of published research data from RCTs. Conclusions: We conclude that there is a paucity of evidence from RCT on interventions that modify environmental risk factors during pregnancy to potentially improve birth outcomes. Magic bullets approach might not work and that it would be important to study the effect of the broader interventions, particularly in LMIC settings. Global interdisciplinary action to reduce harmful environmental exposures, is likely to help to reach global targets for LBW reduction and sustainably improve long-term population health.