An estimated 15.5% of couples in the United States experience infertility, with that number going over 20% for couples over 35.
There are some suggestions that fertility in the US has been declining over the past decades. Reasons include the "modernization theory", or the idea that couples are waiting longer to start their families, often until after 35, which is when fertility noticeably decreases.
Another reason includes environmental exposures. Lead, pesticides, and endocrine-disrupting chemicals (such as BPA, pthalates, and other "xenoestrogens"), alter normal hormone functioning and lead to decreased fertility. These environmental toxins may account for the declining levels of testosterone in men, which has been steadily declining 1% per year, which is the same rate of decline seen in sperm production.
Some studies show that despite the decreased sperm production, fertility levels have remained constant. But those numbers are no comfort to the millions of Americans struggling with starting their family. Some factors are uncontrollable. However, some factors, including exposure to environmental toxins, are more easily managed.
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