Phthalates Linked to Reduced Fertility in IVF

Urinary metabolite levels of di-2-ethylhexyl-P (DEHP) phthalates are associated with a significantly higher risk of in vitro fertilization (IVF) failure.

Researchers at Massachusetts General Hospital (MGH; Boston, USA) conducted a prospective cohort study involving 231 women (aged 18-45) who had had a total of 325 fresh treatment cycles at the MGH Fertility Center between 2004 and 2012. Urine samples were obtained at the start of treatment and either at the early/mid-follicular phase or at oocyte retrieval. The researchers measured urinary metabolites of several phthalates, including mono(2-ethylhexyl)-P (MEHP), monobutyl-P (MBP), and the sum of di-2-ethylhexyl-P phthalates (sum-DEHP).They also assessed various markers of response to IVF, including serum peak estradiol, implantation failure, and the number of retrieved, mature, and fertilized oocytes.

The results showed that urinary phthalates were present in over 95% of the samples, with significant increased risks of IVF failure across increasing quartiles of sum-DEHP levels; a similar pattern was detected for the metabolite MBP, but the relationship was not significant. The researchers also found a decline in the number of retrieved oocytes with increasing MEHP quartiles, and a similar trend with increasing sum-DEHP quartiles, although it was not significant. There was also a decrease in the number of mature oocytes with increasing MEHP quartiles and sum-DEHP metabolites. The study was presented at the European Society of Human Reproduction and Embryology meeting, held during July 2013 in London (United Kingdom).

“Phthalates, chemicals found in plastics, fragrances, and cosmetics, may affect the chances of successful in vitro fertilization,” concluded lead author Irene Souter, MD, and colleagues. “However, there were no associations between urinary phthalate metabolites and peak estradiol, rates of fertilization, or embryonic cleavage. The study was limited because it precluded assessment of long-term exposure to phthalates, and because the results may not be generalizable to women who are conceiving naturally.”

Phthalates are used primarily to soften polyvinyl chloride (PVC) in a large variety of products, include adhesives and glues, electronics, agricultural adjuvants, building materials, personal-care products, medical devices, detergents and surfactants, packaging, children's toys, pharmaceuticals, food products, textiles and more. People are commonly exposed to phthalates since they are easily released into the environment, and as a result, phthalates are being phased out of many products in the United States, Canada, and European Union due to health concerns.

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