Kate Johnson

November 05, 2014

HONOLULU — In vitro fertilization (IVF) pregnancy rates are lower when the man has been exposed to high levels of the environmental pollutant bisphenol A (BPA), according to new research.

"This is the first study to assess preconception BPA exposure in both partners to predict implantation outcome after IVF," said researcher Kwang Rae Kim, MD, PhD, from the i-Dream Clinic at MizMedi Hospital in Seoul, Korea.

Previous studies have shown adverse reproductive effects in women exposed to BPA, Dr Kim reported.

The effect of male exposure on implantation rates might reflect differences in the gamete development process. "The toxic effect of recent exposure to BPA could be more powerful on spermatogenesis than the oocyte development," she told Medscape Medical News.

Dr Kim presented results from the study here at the American Society for Reproductive Medicine (ASRM) 2014 Annual Meeting.

The prospective cohort study involved 105 couples undergoing in vitro fertilization. Urine from both partners was collected on the day of oocyte and sperm collection.

Levels of BPA above 3 ng/mL were categorized as high, and levels below 3 ng/mL were categorized as low. Mean BPA levels were 3.1 ng/mL in the women and 3.9 ng/mL in the men.

For men, the only significant difference was in the implantation rate, which was significantly higher in the low BPA group than in the high BPA group (48.4% vs 24.4%; P = .015).

As a result, the odds ratio of implantation failure increased to 2.9 in the quartile of men with the highest concentration of BPA, compared with the quartile with the lowest concentration.

"Interestingly, sperm parameters were not affected negatively, and were slightly better in the high BPA group," said Dr Kim.

Table. Sperm Parameters

Parameter High BPA Group Low BPA Group
Concentration (million/mL) 54.1 49.1
Motility (%) 35.1 29.3

 

For women, there were no differences between the high and low BPA groups for fertility parameters such as the number of retrieved oocytes, fertilization rate, and implantation rate. However, peak estradiol was higher in the low BPA group than in the high BPA group (1412.7 vs 1150.1 pg/mL; P = .686).

"Although early and still very preliminary, studies like this, in which actual chemical exposure levels were measured in both sexes, as opposed to being estimated, are some of the most powerful to date to examine the effects of environmental toxins on human fertility," said Paul Turek, MD, president of the Society for Male Reproduction and Infertility (an ASRM affiliate).

No mechanisms have been defined, but "the results agree with animal studies showing that BPA may very well be an endocrine disruptor," he told Medscape Medical News.

This study was supported by the Department of Laboratory Medicine at Asan Medical Center in Seoul, Korea. Dr Kim and Dr Turek have disclosed no relevant financial relationships.

American Society for Reproductive Medicine (ASRM) 2014 Annual Meeting: Abstract O-53. Presented October 20, 2014.

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