Causes

Lifestyle causes

The lifestyle risk factors for male and female infertility are the same. Some of the common causes for infertility are:

Age
With age, Fertility starts to decline. Most of the times, women older than 35 years have fertility problems. Male fertility also declines with age, but in males it is more gradual than when compared to female age-related fertility decline.
Smoking & Consuming hot drinks, caffeine and drugs

According to the research, smoking cigarettes can affect sperm quality, loss of eggs and speeding up menopause for years. Consumption of alcohol and caffeine may impair conceptions as well as infertility
Over exercise
According to most of the doctors, restrained exercise is well for women. But, women who regularly do aerobics and other vigorous exercise may ovulate less or stop ovulating. It is recommended to take a break from vigorous exercise if you are trying to conceive.
Attain ideal weight
Achieve body mass index [BMI] between 25 and 31. BMI between 25 and 31 are considered to be more fertile. Women with less body weight or fat can lead to irregular ovulation
Put an end to contraceptive method and birth control pills
For few women, it's difficult to conceive for several months even after discontinuing birth control pills. Hence, women's body takes time to become normal for conceiving.

Occupational causes

Over exposure to environmental elements such as toxins, heat and certain harmful chemicals can reduce sperm production which causes infertility. Also, exposure to certain matals, pesticides and solvents can hugely affect fertility in both women and men.

Some of the causes include:

Metal exposure. Exposure to heavy metals like lead may cause infertility.
Radiation or X-rays. Exposure to radiation and X-rays can reduce sperm production. With continuos exposure to radiation, sperm functions can be permanently damaged.
Industrial chemicals. Exposure to benzenes, xylene, toluene, pesticides, organic solvents, painting materials, herbicides etc. may contribute to low sperm counts.
Overheating the testicles. Frequent use of hot tubs and sauna may lower your sperm count temporarily.