Associations between particulate matter exposure during pregnancy and executive function of toddlers in a prospective cohort study

Background: Exposure to particulate matter (PM) has been found to be associated with impaired cognitive function. However, limited evidence is available on the relationship between PM exposure in the prenatal period and toddler executive function (EF), and the potential influence of breastfeeding.

Methods: The study included 1106 mother-toddler pairs recruited between 2015 and 2019. We assessed mothers' PM₁, PM_2.5, and PM₁₀ prenatal exposure with a satellite-based dataset at a 1 × 1 km spatial resolution and assigned to participants based on residential addresses. Toddler EF was measured using the Behavior Rating Inventory of Executive Function for Preschoolers (BRIEF-P) questionnaire, higher BRIEF-P scores indicated poorer EF in toddlers. We determined the associations of PM exposure during pregnancy with BRIEF-P scores using multiple linear regression models.

Results: In the first trimester, a 10 μg/m³ increase of PM was associated with 1.49 (95% confidence interval [CI]: 0.14-2.83; PM₁), 0.68 (95% CI: 0.10-1.26; PM_2.5), and 0.63 (95% CI: 0.07-1.20; PM₁₀) elevated toddler global executive composite index scores, respectively. In the stratified analysis, a 10 μg/m³ increase in first trimester PM₁ exposure was related to 0.54 (95% CI: 0.19-0.89) higher inhibition scores in toddlers who received complementary breastfeeding for less than six months and -0.15 (95% CI: 0.81-0.51) higher inhibition scores in toddlers who received complementary breastfeeding for six months or more (P for interaction: 0.046). Additionally, a 10 μg/m³ increment in first trimester PM₁ exposure was related to 0.36 (95% CI: 0.13-0.59) higher emotional control scores in toddlers who received breastfeeding for less than 12 months and -0.54 (95% CI: 1.25-0.18) higher inhibition scores in toddlers who received breastfeeding for no less than 12 months (P for interaction: 0.043).

Conclusions: PM exposure during the first trimester, especially PM₁, has been linked to lower toddler EF performance in toddlers; feeding with breast milk may be a potential protective measure.