Fetal Growth Outcomes Following Peri-Implantation Exposure of Long Evans Rats to Noise and Ozone Differ by Sex
Background
Exposure to air pollution and high levels of noise have both been independently associated with the development of adverse pregnancy outcomes including low birth weight However, exposure to such environmental stressors rarely occurs in isolation and is often co-localized, especially in large urban areas. ·
Methods
The purpose of this study was to compare three effects of combined exposure to noise(N) ozone (03), compared to either exposure alone. Long-Evans dams were exposed to air or 0.4 ppm ozone for 4 hon gestation day(GD) Sand 6, coinciding with implantation receptivity. A subset of dams from each exposure group was further exposed to intermittent white noise (- 85dB) throughout the dark cycle following each inhalation exposure (n = 14 - 16/group). Uterine artery ultrasound was performed on GD 15 and 21. Fetal growth characteristics and indicators of placental nutrient status were measured at GD21.
Results
Exposure to ozone+ quiet (03 + Q) conditions reduced uterine arterial resistance at GD 15 compared to air + quiet (A + Q) exposure, with no further reduction by GD2I. By contrast, exposure to air+ noise (A + N) significantly increased uterine arterial resistance at both GD I5 and 21. Notably, while peri implantation exposure to 03+Q conditions reduced male fetal weight at GD21, this effect was not observed in the air noise (A + N) or the ozone+ noise (0 3 + N) exposure groups. Fetal weight in female offspring was not reduced by ozone exposure alone (03 + Q) nor was it affected by air + noise (A + N) or by combined ozone+ noise (03+ N) exposure.
Conclusions
These data indicate that exposure to ozone and noise differentially impact uterine blood now, particularly at mid-gestation, with only ozone exposure being associated with sex-dependent fetal growth retardation in male offspring.