Alcohol and smoking
Becoming overweight or underweight
Defined as the inability to achieve a pregnancy after at least a year of trying infertility affects more than 20 percent of North American couples. Experts cannot explain why the infertility rate has almost doubled in the last 25 years, but at least three factors stand out; the growing trend for couples to delay marriage and parent-hood until their most fertile years are past, the rise in sexually transmitted diseases, and a puzzling drop in sperm production.
While nutrition is not a leading cause of infertility, consuming a healthful diet enhances the chance of conceiving and delivering a healthy baby.
The leading cause of female infertility is the failure to ovulate, which may be influenced by the diet, hormonal imbalances, and a variety of other factors. Women are very thin or markedly overweight often do not ovulate because the amount of body fat is closely associated with estrogen levels. Women who have very little body fat-professional athletes, dancers, models and chronic dieters- often stop menstruating and ovulating. Women who are obese may have abnormally elevated levels of estrogen, which can also result in a failure to ovulate.
A low sperm count is the major cause of male infertility, and for unknown reasons, men worldwide are producing fewer sperm than a few decades ago. Some scientists believe certain pesticides, which have estrogenlike effects, may be linked to the declining count. Alcohol and tobacco use lower sperm production and should be avoided if there is difficulty conceiving.