Smoking has an adverse impact on the fertility of both men and women. For women, smoking is harmful to the ovaries, accelerates egg loss and may reduce the age of menopause by several years. Studies indicate that smoking can predispose eggs to genetic abnormalities and increase the risk of miscarriage, and possibly of ectopic pregnancy. For men, smoking is associated with abnormalities in the quality and quality of sperm production. Smoking can also lead to impotence by causing damage to blood vessels, resulting in weak and ineffective erections.

For women, some medications can affect ovulation and cause periods to be irregular. For men, some medications may affect sperm quality.

High cholesterol levels may impair fertility in couples trying to achieve a pregnancy, according to a study by researchers at the National Institutes of Health, the University at Buffalo and Emory University in the US. In the study, couples in which each partner had high cholesterol took the longest time to conceive; couples in which the woman had high cholesterol and the man didn’t also took longer to conceive when compared to couples in which both partners had cholesterol levels in the acceptable range.

Stress is difficult to quantify, but we do know that too much stress is bad, as it can have an adverse effect on libido, menstrual cycles and ovulation.

Heavy drinking can definitely affect fertility, increasing the length of time it takes to get pregnant and reducing the chances of having a healthy baby. In females, the likelihood of heavy or irregular menstrual periods, miscarriage and infertility is greater when alcohol is consumed above the guideline levels (no more than two standard drinks a day: Bradley et al, 1998). In fact, the Australian National Health and Medical Research Council’s alcohol guidelines suggest that, for women who are pregnant or planning a pregnancy, not drinking is the safest option.

A study from the Netherlands found that, for every BMI unit over 29, the chance of pregnancy was reduced by four percent when compared with women whose BMIs were between 21 to 29. Women who were severely obese, with BMIs between 35 and 40, had up to 43 percent less chance of achieving pregnancy compared with women whose BMI was below 29.

Depending on the size and location of a uterine fibroid, it could affect fertility.

In one study, women with healthy gums conceived sooner than those with gum disease. The women with healthy gums became pregnant within five months, compared with just over seven months for women with gum disease. However, more research is needed in this area.