Prenatal particulate matter exposure and Intrauterine Fetal Death

Background: Intrauterine Fetal Death (IUFD) is a rare and tragic pregnancy complication. The main causes for IUFD are largely unknown. Particulate Matter (PM)2.5 exposure has been suggested as an IUFD risk factor. Objectives: To study the association between maternal PM2.5 levels and IUFD risk, to address ethnicity as a possible effect modifier, and to identify a prenatal period during which PM2.5 is most harmful regarding IUFD risk. Methods: This is a retrospective cohort study, which included pregnant women at the Soroka University Medical Center between the years 2003–2017. Estimated PM2.5 levels were calculated per residence, using a hybrid model incorporating daily satellite remote sensing data at a 1 km spatial resolution. Multiple gestations, fetuses with congenital malformations or chromosomal abnormalities were excluded. Mean PM2.5 level was calculated per trimester, the entire pregnancy and the last gestational week. Analyses were also performed separately for the two ethnic groups in the study: Jews and Bedouin-Arabs. Multivariable analysis were applied to study the association between PM2.5 exposure at the different periods and IUFD risk. Results: The study included 87,887 pregnancies, 444 (0.5%) ended with IUFD. Mean PM2.5 levels ranged between 18.18 and 22.32 μm. First trimester and entire pregnancy PM2.5 levels were significantly associated with increased IUFD risk among Jewish women only. In a multivariable model, for every 10 μg/m³ unit increase in PM2.5 the risk for IUFD increases by 2.98 (95%CI 1.50–5.90) and by 3.61 (95%CI 1.32–9.85) during first trimester and the entire pregnancy, respectively, while adjusting for maternal age, smoking, socioeconomic score and season. Conclusions: In this retrospective cohort an association was found between PM2.5 levels and IUFD among Jewish women only. These results strengthen the importance of addressing this effect modifier when studying air pollution effects on human health.