On the previous page, we brought up the connection between obesity and infertility. That's because there's a growing mountain of evidence linking the two.
For example, research shows that spontaneous pregnancy (pregnancy without fertility treatments) becomes less likely the higher a woman's body mass index (BMI) is more than 29 [source: Science Daily]. In particular, severely obese women are 43 percent less likely to get pregnant than women who are of average weight or simply overweight (but not obese) [source: Boyles].
And it's not just women whose fertility is influenced by weight. Men, too, can experience reproductive challenges due to obesity. A Danish study found that men with a BMI over 25 had around 22 percent lower sperm concentration and 24 percent lower sperm count than men of normal weight [source: WebMD].
Interestingly, the study examining female fertility noticed problems primarily in obese women (BMI over 30); whereas the study observing male fertility sees trouble starting when the BMI is around 25, which is considered overweight but not yet obese.
While such results may be confusing, the best lesson to be taken from them is -- overweight or obese -- both partners should consider losing weight, if necessary, to increase the odds of conception.
To learn more about how weight affects fertility, head to the next section.