Associations between paternal urinary phthalate metabolite concentrations and reproductive outcomes among couples seeking fertility treatment

•We assessed reproductive outcomes among couples undergoing assisted reproduction.•Specific gravity-adjusted paternal urinary phthalate concentrations were quantified.•Some phthalates were associated with decreased odds of implantation and live birth. Limited evidence suggests that male exposure to ubiquitous environmental phthalates may result in poor reproductive outcomes among female partners. This analysis included male–female couples undergoing in vitro fertilization (IVF) and/or intrauterine insemination (IUI). We evaluated associations between the geometric mean of paternal specific gravity-adjusted urinary phthalate concentrations prior to the female partners’ cycle and fertilization, embryo quality, implantation, and live birth using generalized linear mixed models. Two-hundred eighteen couples underwent 211 IVF and 195 IUI cycles. Trends were observed between paternal urinary mono-3-carboxypropyl phthalate (MCPP; P=0.01) and mono(carboxyoctyl) phthalate (MCOP; P=0.01) and decreased odds of implantation. MCPP and MCOP were also associated with decreased odds of live birth following IVF (P=0.01 and P=0.04, respectively), and monobutyl phthalate above the first quartile was significantly associated with decreased odds of live birth following IUI (P=0.04). However, most urinary phthalate metabolites were not associated with these reproductive outcomes. Selected phthalates were associated with decreased odds of implantation and live birth.