A pilot study on association between phthalate exposure and missed miscarriage

OBJECTIVE: The incidence of missed miscarriage has been increasing during the past decade in China and the etiology of about half of the cases remains unclear. Exposure to phthalates has been considered as a risk factor. The aim of this paper is to assess the association between exposure to phthalates and missed miscarriage. PATIENTS AND METHODS: A case-control study was performed including 150 cases of missed miscarriage and 150 matched controls with normal pregnancies. The levels of phthalate exposure were compared between the two groups by measuring 13 phthalate metabolites in urine samples. Blood samples were collected for serum hormone measurement to assess the relationship between serum hormone level and phthalate exposure. RESULTS: The urinary levels of metabolites of di-(2-ethylhexyl)phthalate (DEHP) and dimethyl phthalate (DMP) were significantly higher in the cases than in the controls. A strong dose-response relationship was observed between urinary metabolite levels and the odds of missed miscarriage. Monomethyl phthalate (MMP), a metabolite of DMP, and mono-2-ethylhexyl phthalate (MEHP), a metabolite of DEHP, each had significant negative correlation with maternal serum hormone levels. CONCLUSIONS: In the current study, exposure to DEHP and DMP was found to be associated with missed miscarriage. Interruption of hormone synthesis by DMP and DEHP metabolites represents a plausible mechanism of phthalate reproductive toxicity.