Indoor NO₂, temperature, and humidity in relation to maternal stress, sleep, and cognitive performance during pregnancy

Evidence characterising indoor environmental exposures and their effects on maternal neurobehavioural well-being during pregnancy remains scarce.

To estimate the associations between indoor residential environmental exposures (nitrogen dioxide (NO₂), temperature, and relative humidity (RH)) and maternal neurobehavioural well-being (measured as perceived stress, sleep quality, and cognitive performance).

We included pregnant individuals (n = 906) from the population-based Barcelona Life Study Cohort (BiSC) who were recruited from 2018 to 2021. Weekly average indoor residential NO₂ concentrations, temperature, and RH were objectively measured in participants' homes at ∼ 12 and ∼ 32 weeks of gestation using indoor monitoring devices. Linear, negative binomial, and mixed-effects regression models estimated the associations between indoor environmental exposures and perceived stress (10-item Perceived Stress Scale [PSS-10]), sleep quality (Pittsburgh Sleep Quality Index [PSQI]), and cognitive performance (N-back reaction time and Primary Mental Abilities-Revised [PMA-R]); PSQI was assessed at both visits, while PSS-10 and cognitive tests were performed at ∼ 32 weeks of gestation only.

After covariate adjustment, higher indoor NO₂ exposure was associated with higher perceived stress (0.66 points (95 % confidence interval [CI] 0.11, 1.21; p = 0.019)) and a greater increase in PSS-10 scores for a NO₂ interquartile range increase (11.2 µg/m³) but not with sleep quality or cognitive performance. Indoor temperature and RH metrics, including nighttime minima and maxima, were not associated with any outcome.

Our findings suggest an association between indoor NO₂ concentration and prenatal perceived stress, indicating that the residential environment may be a relevant factor in maternal antenatal health that warrants further investigation.