As many as 20% of infertile couples in the United States
have unexplained reasons for their infertility.
Now, new research led by Catherine Racowsky, PhD, director
of the Assisted Reproductive Technologies Laboratory at Brigham and Women's
Hospital (BWH), shows that exposure to BPA (Bisphenol-A) could be a
contributing factor to why some infertile couples are having difficulty
conceiving. The study will be published online on July 31, 2013 in the journal Human Reproduction.
"To our knowledge, this is the first study that has
shown that BPA has a direct effect on egg maturation in humans," said Dr Racowsky.
"Because exposure to BPA is so ubiquitous, patients and medical
professionals should be aware that BPA may cause a significant disruption to
the fundamentals of the human reproductive process and may play a role in
The randomised trial examined 352 eggs from 121 consenting
patients at a fertility clinic. The eggs, which would have otherwise been
discarded, were exposed to varying levels (20 ng/ml, 200 ng/ml and 20 ng/ml) of
BPA in a laboratory setting. An egg from each patient was not exposed to BPA
and served as the control.
examined the eggs and found that exposure to BPA caused:
decrease in the percentage of eggs that matured.
increase in the percentage of eggs that degenerated.
increase in the percentage of eggs that underwent spontaneous activation, the
abnormal process when an egg acts as though it has been fertilized, even though
it has not been.
As the BPA dose increased, there was a decreased likelihood
of maturity, an increased likelihood of degeneration and an increased
likelihood of spontaneous activation. Additionally, among the mature eggs,
there was a significant trend toward a decreased incidence of bipolar spindles
and aligned chromosomes with an increased dose of BPA. Researchers note that
these results are similar to the previous research examining the impact of BPA
exposure on animal eggs.
Racowsky said, "Our data show that BPA exposure can
dramatically inhibit egg maturation and adds to a growing body of evidence
about the impact of BPA on human health. I would encourage further research to
gain a greater understanding of the role that BPA plays in infertility."