Oral contraceptive use as a determinant of serum concentrations of perfluoroalkyl substances (PFAS) among women in the Norwegian mother and child cohort (MOBA) study

摘要

Previous studies have shown that reproductive factors can be significant determinants of serum perfluoroalkyl substances (PFAS) concentrations in women. This analysis examined the distribution of seven PFASs in a cohort that included women from two previous case-base studies conducted in the Norwegian Mother and Child Cohort (MoBa) Study. Several models were created to predict the impact of oral contraceptive (OC) use (pill and mini pill) on serum PFAS concentrations. I found that women who reported using OCs in the past 12 months had increased serum PFAS concentrations compared to women who had not reported use of OCs in the past 12 months. Additional characteristics of oral contraceptive use were analyzed, including age at first use (among OC users), lifetime duration of OC use, and recency of OC use. The interaction between duration of use and recency of use was also examined. Among OC users, age at first OC use was not found to be a strong determinant of serum PFAS concentrations. However, compared with never OC users, longer duration of OC use and more recent OC use were each found to be important determinants of increased serum PFAS concentrations. Duration of OC use and recency of OC use did not appear to have an interactive effect on serum PFAS concentrations, except in the case of women who reported a short lifetime duration of OC use (i.e., less than three years). Among these women, OC use appeared to impact PFAS concentrations only among recent OC users. Several sensitivity analyses were conducted. First, a weighted analysis was conducted using the inverse of the sampling probabilities for each group. Second, I conducted an analysis limited to the base groups of both sub-studies. Lastly, I reran the models limited to Study A participants and included interpregnancy interval as a covariate. Results were largely unchanged in each of these sensitivity analyses. Overall, this analysis demonstrates that OC use should be considered when investigating the relationship between reproductive outcomes and serum PFAS concentrations in women.