Objective To investigate the association between exposure to inhalable particles (PM₁₀) during pregnancy and full-term low birth weight.

Methods The hospitalization data of 110 171 pregnant and parturient women, who had their deliveries in 22 hospitals monitored in Hebei Province, China in 2016-2017, were collected. The exposure of pregnant and parturient women to PM₁₀ at different stages of pregnancy in different cities was estimated based on the daily air quality monitoring data of their cities. The association of PM₁₀ exposure at different stages of pregnancy and during the whole pregnancy with full-term low birth weight in the women stratified by different features was analyzed by logistic regression, and the sensitive exposure window was validated by the distributed lag nonlinear model.

Results The exposure level of PM₁₀ at all stages of pregnancy in the full-term low birth weight group was higher than that in the full-term non-low birth weight group. PM₁₀ exposure during pregnancy increased the risk of full-term low birth weight. The risk of full-term low birth weight increased to 1.039, 1.012, 1.012, and 1.016 times the original value for every 10 μg/m³ increase in PM₁₀ exposure during the whole pregnancy and in the first, second, and third trimesters of pregnancy, respectively (P < 0.05). The stratified analysis showed that the risk of full-term low birth weight increased to 1.039 times the original value for every 10 μg/m³ increase in PM₁₀ mass concentration during the whole pregnancy in women aged < 35 years with single pregnancy. In addition, an increased risk of full-term low birth weight was associated with PM₁₀ exposure at gestational 20th to 25th weeks.

Conclusion PM₁₀ exposure during pregnancy, especially at gestational 20th to 25th weeks, is a risk factor for full-term low birth weight. An age of < 35 years and single pregnancy in pregnant women are potential influencing factors for the association of PM₁₀ exposure with the risk of full-term low birth weight, thus protective measures against exposure should be adopted among pregnant women.