Association between pregnancy loss and ambient PM2·5 using survey data in Africa: a longitudinal case-control study, 1998–2016

Abstract

Background Increasing evidence from epidemiological studies suggests that maternal exposure to ambient PM 2•5 can increase the risk of pregnancy loss. However, no studies have been done in low-income countries such as those in Africa, which have the highest incidences of pregnancy loss. In this study, we aimed to analyse the association between PM 2•5 and pregnancy loss, including miscarriage and stillbirth. Methods This self-compared case control study collected data on mothers who reported at least two births (at least one case of pregnancy loss plus at least one normal delivery) in the African Demographic and Health Surveys. Gestational exposure to PM 2•5 was assessed using a state-of-the-art estimator based on satellite measurements and chemical transport model outputs. Each case of pregnancy loss was compared with the successful control deliveries in the same mother. We estimated the association between gestational exposure to PM 2•5 and pregnancy loss using a conditional logistical model with multiple adjustments, and assessed it using the odds ratio (OR) derived from the regression.

Particulate Matter 2.5 Induced Developmental Cardiotoxicity in Chicken Embryo and Hatchling

“…Many toxic components, such as the heavy metals and PAHs are present in PM, which are capable of exerting developmental toxicities (Shankar et al, 2019;Zhao et al, 2020). Epidemiological studies revealed that developmental exposure to PM resulted in increased risk of asthma (Kravitz-Wirtz et al, 2018), decreased airway antimicrobial activity (Zhang et al, 2019), low birth weight (Wang et al, 2019b), and pregnancy loss (Xue et al, 2019).…”

Ambient Air Pollution, Extreme Temperatures and Birth Outcomes: A Protocol for an Umbrella Review, Systematic Review and Meta-Analysis

“…The evidence in the existing reviews on ambient air pollution and/or temperature and birth outcomes [19][20][21][22][23][24][25]30,31,37] is heavily based on studies for high income countries while acknowledging lack of evidence from low-and middle-income countries (LMICs). Conceivably, this may be due to generally limited environmental health researches in developing countries such as Africa [38,39] and even in some East Asian and Pacific Island countries. Despite their limitations, analytical cross-sectional and ecological studies provide exploratory information to generate hypotheses for possible links between environmental factors and disease outcomes [18,40].…”

“…Consequently, one conclusion made by Rees et al [49] is that "we are not only potentially underestimating the impact we might also not know how bad it is until it is too late". Results from recent studies [38,39,50] using Demographic Health Survey (DHS) data and gridded satellite-based estimates of PM 2.5 across Africa indicate strong significant associations. For instance, exposure to early-life carbonaceous PM 2.5 increased the odds of neonatal mortality (OR: 1.22; 95% CI: 1.11-1.35) on the log PM 2.5 exposure level [38], higher odds for pregnancy loss cases with 26.64 µg/m 3 exposure than the control with 25.69 µg/m 3 exposure level (1.22; 1.107-1.137), and this included miscarriage (1.125; 1.109-1.142) and stillbirth (1.094; 1.05-1.38) per 10 µg/m 3 increase in PM 2.5 exposure [39].…”

“…Results from recent studies [38,39,50] using Demographic Health Survey (DHS) data and gridded satellite-based estimates of PM 2.5 across Africa indicate strong significant associations. For instance, exposure to early-life carbonaceous PM 2.5 increased the odds of neonatal mortality (OR: 1.22; 95% CI: 1.11-1.35) on the log PM 2.5 exposure level [38], higher odds for pregnancy loss cases with 26.64 µg/m 3 exposure than the control with 25.69 µg/m 3 exposure level (1.22; 1.107-1.137), and this included miscarriage (1.125; 1.109-1.142) and stillbirth (1.094; 1.05-1.38) per 10 µg/m 3 increase in PM 2.5 exposure [39]. Some researchers [38] have suggested lowering World Health Organization (WHO) air quality guidelines below the current 10 µg/m 3 total mass guideline for harmful carbonaceous PM 2.5 excluding dust and sea-salt levels [38].…”

Are we ready to establish a causal relationship between air pollution and pregnancy loss?

“…The study by Tao Xue and colleagues 7 is the first large study to examine the association between fine particles and pregnancy loss across 33 African countries. The authors took advantage of a large multicountry sample of 42 952 women with selfreported pregnancy losses (1998-2016), who also had a successful pregnancy before or after the index loss.…”