Association between Phthalate Metabolites and Risk of Endometriosis: A Meta-Analysis

Objective: The association between phthalates and endometriosis risk is inconclusive. This meta-analysis aims to evaluate the association between five different phthalate metabolites and endometriosis, based on current evidence. Methods: The literature included PubMed, WOS (web of science), and EMBASE, published until 3 March 2019. We selected the related literature and evaluated the relationship between phthalates exposure and endometriosis risk. All statistical analyses were conducted with STATA version 12.0. Results: Data from eight studies were used in this review. The results of this analysis showed that mono-(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP) exposure was potentially associated with endometriosis (OR = 1.246, 95% CI = 1.003-1.549). We have not found positive results in mono(2-ethylhexyl) phthalate (MEHP), monoethyl phthalate (MEP), monobenzyl phthalate (MBzP) and mono(2-ethyl-5-oxohexyl) phthalate (MEOHP) analyses (MEHP: OR = 1.089, 95% CI = 0.858-1.383; MEP: OR = 1.073, 95% CI = 0.899-1.282; MBzP: OR = 0.976, 95% CI = 0.810-1.176; MEOHP: OR = 1.282, 95% CI = 0.874-1.881). In subgroup analyses for regions, the associations were significant between MEHHP and endometriosis in Asia (OR = 1.786, 95% CI = 1.005-3.172, I² = 0%), but not in USA (OR = 1.170, 95% CI = 0.949-1.442, I² = 45.6%). Conclusions: Our findings suggested a potential statistical association between MEHHP exposure and endometriosis, particularly, the exposure of MEHHP might be a potential risk for women with endometriosis in Asia. However, positive associations between the other four Phthalate acid esters (PAEs) and endometriosis was not found. Given the weak strength of the results, well-designed cohort studies, with large sample sizes, should be performed in future.