Ambient PM_2.5 exposure and salivary cortisol output during pregnancy in a multi-ethnic urban sample

Abstract

Objectives

Evidence from murine research supports that fine particulate matter (PM_2.5) may stimulate the hypothalamic-pituitary-adrenal axis, leading to elevated circulating glucocorticoid levels. Epidemiologic research examining parallel associations document similar associations. We examined these associations among a diverse sample of pregnant individuals exposed to lower levels of ambient PM_2.5.

Materials and Methods

Participants included pregnant individuals enrolled in the PRogramming of Intergenerational Stress Mechanisms (PRISM) pre-birth cohort. Daily residential PM_2.5 exposure was estimated using a satellite-based spatial-temporal hybrid model. Maternal 3rd trimester salivary cortisol levels were used to calculate several features of the diurnal cortisol rhythm. We used multivariable linear regression to examine PM_2.5 during the pre-conception period and during each trimester in relation to cortisol awakening rise (CAR), slope, and area under the curve relative to ground (AUC_G).

Results and Discussion

The average PM_2.5 exposure level across pregnancy was 8.13 µg/m³. PM_2.5 in each exposure period was positively associated with AUC_G, a measure of total cortisol output across the day. We also observed an inverse association between PM_2.5 in the 3rd trimester and diurnal slope, indicating a steeper decline in cortisol throughout the day with increasing exposure. We did not detect strong associations between PM_2.5 and slope for the other exposure periods or between PM_2.5 and CAR for any exposure period.

Conclusions

In this sample, PM_2.5 exposure across the preconception and pregnancy periods was associated with increased cortisol output, even at levels below the U.S. National Ambient Air Quality Annual Standard for PM_2.5 of 12.0 µg/m³.

Keywords:

• Fine particulate matter
• PM2.5
• pregnancy
• cortisol
• HPA axis

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by grants from the National Heart, Lung, & Blood Institute [R01HL095606; R01HL114396], the Eunice Kennedy Shriver National Institute of Child Health and Human Development [R21HD080359], the National Center for Advancing Translational Sciences [UL1TR001433], the National Institute of Environmental Health Sciences [K99ES032029, P30ES023515, P30ES000002] the ECHO Consortium [UG3OD023337], and USEPA grant RD-83587201. Its contents are solely the responsibility of the grantee and do not necessarily represent the official views of the USEPA. Further, USEPA does not endorse the purchase of any commercial products or services mentioned in the publication.