Exposure to polybrominated diphenyl ether (PBDE) flame retardants is widespread, with 97% of Americans having detectable levels. Yet there have been no published studies of their effects on human fertility – until now. A study to be published in the January 26 issue of Environmental Health Perspectives reports that four PBDE congeners were correlated with longer times to pregnancy.
While this finding is expected and unsurprising, it does seem surprising that researchers have found no correlations with the presence of PBDEs and menstrual irregularity.
It is likely that the influence of flame retardants on fertility is through ovulatory disturbances, meaning anovulation and short luteal phase cycles within regular menstruation. Ovulatory disturbances, especially short luteal phase are very common and almost always “subclinical” (meaning nothing seems out of the ordinary). Evidence from population-based data suggest that 10-20% of all REGULAR cycles are anovulatory. Given the relative incidence of anovulation (4%) and short luteal phase cycles (25%) across one year in 66 women monitoring continuously who were initially proven normally menstruating and ovulatory in two consecutive cycles, it likely that flame retardant exposure shortens luteal phase length and thus the amount of time following ovulation that progesterone has to mature and make the endometrium ready for implantation. This is the most subtle, but still consequential (not only for fertility, but also bone–see CeMCOR’s newsletter article series at http://www.cemcor.ubc.ca) form of disruption of women’s reproduction.