7/8/13
by Kristina Fiore
Staff Writer, MedPage Today
Action Points
- Note that this study was published as an abstract and presented at a conference. These data and conclusions should be considered to be preliminary until published in a peer-reviewed journal.
- Urinary phthalate metabolite concentrations were associated with lower oocyte yield and increased odds of implantation failure in in vitro fertilization.
Phthalates, chemicals found in plastics, fragrances, and cosmetics, may affect the chances of successful in vitro fertilization, researchers reported.
In a prospective cohort study, urinary metabolite levels of the phthalates in the family of di-2-ethylhexyl-P (DEHP) were associated with significantly increased risks of implantation failure across increasing quartiles of the metabolite (P=0.031 for trend), according to Irene Souter, MD, of Massachusetts General Hospital, and colleagues.
They presented their findings at the European Society of Human Reproduction and Embryology meeting in London.
“Our data support the hypothesis that exposure to specific phthalates might lead to adverse female reproductive outcomes,” Souter said in a statement.
Phthalates are used in a host of plastics, including PVC and vinyl, to soften them, and in personal care products and aerosols with fragrances in them. These products are ubiquitous in the environment and studies have shown them to be linked with reproductive issues in men, since they have been known to mimic the hormone testosterone.
But the effects of phthalates are less well-studied in women, particularly with regard to reproductive health.
Specifically, Souter and colleagues questioned whether phthalates had an impact on various factors among women having IVF, such as ovarian response, oocyte yield, embryonic development and implantation failure.
They followed 231 women ages 18 to 45 who’d had a total of 325 fresh treatment cycles at Massachusetts General Hospital Fertility Center between 2004 and 2012.
The researchers took urine samples at the start of treatment and either at the early/mid-follicular phase or at oocyte retrieval. They looked for 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.
Overall, the researchers detected urinary phthalates in more than 95% of the samples.
They found significant increased risks of implantation failure across increasing quartiles of sum-DEHP levels (P=0.031):
- Q2 — OR 1.41
- Q3 — OR 1.76
- Q4 — OR 2.05
They saw a similar pattern for the metabolite MBP, but the relationship was not significant (P=0.087):
- Q2 — 1.96
- Q3 — 2.02
- Q4 — 1.85
Souter and colleagues also found a decline in the number of retrieved oocytes with increasing MEHP quartiles: a 4.17% reduction in retrieved eggs for patients in Q2, a 6.19% reduction for those in Q3, and an 11.4% reduction for patients in Q4 (P=0.052).
They reported a similar trend with increasing sum-DEHP quartiles, although it was not significant (9.09%, 9.46%, 10.2%, P=0.074).
There was also a decrease in the number of mature oocytes with increasing MEHP quartiles (P=0.016) and sum-DEHP metabolites (P=0.018).
However, there were no associations between urinary phthalate metabolites and peak estradiol, rates of fertilization, or embryonic cleavage, they reported.
They cautioned that 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.
Still, Souter and colleagues concluded that their results support the hypothesis that phthalates may have an adverse effect on female fertility, particularly when it comes to IVF.
The study was supported by the National Institute of Environmental Health Sciences.
The researchers reported no conflicts of interest.
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