By some studies, the safety nets for retirees have reduced fertility rates.

一些研究表明，退休人员的社会保障体系使生育率降低了。

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Although some animal studies have indicated it is safe, others have linked injections of BPA to breast cancer, liver damage, obesity, diabetes and fertility problems.

虽然一些动物研究表明它是安全的，但是其它研究把双酚A药剂与乳腺癌、肝损伤、肥胖、糖尿病以及生育力等各种问题联系到一起了。

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A woman's weight influences her fertility, two new studies suggest.

两项新的研究表明，女性的体重可能会影响她的生育能力。

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Dr Allan Pacey, senior lecturer at the University of Sheffield and secretary of the British Fertility Society, said some studies had shown an increased risk associated with some assisted reproductive techniques .

BBC: IVF 'not reason for birth risks'

Scientific studies have shown that human fertility starts declining at the age of 31, which is the age many women are having their first babies.

BBC: The cost of fertility treatment 'tourism'

Studies showed that during periods of high fertility, women are more drawn to more rugged, dominant-looking men.

CNN: Beholding beauty: How it's been studied