Image of the Day

persistent chemicals known to decrease fertility by affecting hormone
signaling and increasing time to pregnancy.
When the models accounted for prior pregnancies, the findings still
remained.
What does it mean?
Higher exposure to a variety of persistent pollutants in both men and
women is associated with a longer time to get pregnant – one measure of
fertility. The pollutants studied represent a variety of chemical classes,
including PCBs, perfluorinated compounds and organochlorine pesticides.
The strongest associations were found in men. This study is one of
the first to show that men's chemical exposures are just as important – if
not stronger – than women's in determining fertility issues.
The results are an important first step that shows the exposure to
chemical pollutants in both men and women can strongly affect fecundity.
The study design used in this study is important because it looks at
couples trying to get pregnant rather than assessing exposure effects after
pregnancy occurs. Prospectus studies like this one can get at the "chicken
and egg" – or which came first – issue. Exposure levels are known for
each couple before fertility issues are found, so it is more likely that the
increased chemical exposure is causally related to fecundity.
This study corroborates previous findings that PCBs reduce
fecundity. The results also confirm earlier findings for a lack of
association between fecundity in women and exposure to DDT and its
metabolite DDE. In men, DDE was associated with decreased time to
pregnancy.
Importantly, the magnitude of decreased fecundity – about 20 percent
longer – reported by this study is comparable to other factors known to
cause fertility problems such as male and female age, body mass index
and cigarette smoking. The authors adjusted for these factors in this study,
so they do not contribute here. But the findings underscore the large
impact that environmental pollutants can have on time to pregnancy.
Daily News Digest December 20, 2012