Folate defends against adverse reproductive effects of traffic-related pollution
Supplemental folate intake appears to mitigate the adverse effect of exposure to raised levels of nitrogen dioxide (NO2) on the likelihood of a live birth in women undergoing assisted reproductive technologies (ART), according to a study.
Researchers examined 304 women (513 cycles; mean age, 35.2 years; mean body mass index, 24.3 kg/m2) presenting to a fertility centre. Women in this cohort had high intake levels of total (median, 1,100 µg/day) and supplemental folate (median, 571 µg/day). Overall, 16 percent and 20 percent of the population consumed <400 and ≥1,000 µg/day of supplemental folate, respectively.
In 468 of the initiated cycles with at least one embryo transferred, 290 resulted in implantation, 257 in clinical pregnancy and 206 in live birth. Women contributed an average of 1.7 ART cycles.
During the study period, the median (10th–90th percentile) estimated air pollution concentrations in the 3 months prior to ART were 22.9 ppb for NO2, 34.2 ppb for ozone (O3), 8.5 µg/m3 for fine particulate matter (PM2.5) and 0.49 µg/m3 for black carbon. Correlations between pollutants were modest, with the highest magnitude observed for NO2 and black carbon (r, 0.39). Ozone showed weak inverse correlations with NO2 (r, –0.13) and black carbon (r, –0.22).
Supplemental folate intake significantly modified the association between NO2 exposure and live birth (p=0.01). Among women with supplemental folate intake level of <800 μg/day, the likelihood of live birth decreased by 24 percent for every 20-ppb increase in NO2 exposure. This association was not observed among women with supplemental folate intake levels of ≥800 μg/day.
Furthermore, folate did not modify the associations between other air pollutants and live birth.
The findings indicate that high supplemental folate intake may protect against the adverse reproductive consequences of traffic-related air pollution, the researchers said.