Many women are waiting until their 30s and 40s to have children. In fact, about 20% of women in the United States now have their first child after age 35, which is when fertility starts to decline quickly. About one-third of couples in which the woman is older than 35 years have fertility problems. Male fertility does decline as well with age, but the effect is more gradual than when compared with female age-related fertility decline.
Quit Smoking as soon as possible before attempting pregnancy. Smoking has been associated with both male and female infertility, and an increased risk for miscarriage, low birth weight, and pre-term delivery. These risks are only slightly reduced with passive smoking versus active smoking. According to the American Society for reproductive medicine, smokers must often attempt twice as many in vitro fertilization cycles to achieve pregnancy than a nonsmoker. Female smokers often have poorer egg production. Male smokers often have lower sperm counts and motility as well as increased abnormalities in sperm shape and function. Quitting smoking at least two months (ideally 3+) before attempting IVF or IUI significantly improves chances for conception.
Alcohol and Recreational Drugs
Alcohol and drugs that are ingested while pregnant will also be ingested by the growing fetus. Alcohol and certain drugs are associated with severe birth defects, mental retardation, stillbirth, preterm delivery, low birth weight, and newborn addiction to the substance at delivery.
You should limit your caffeine intake to 1-2 cups per day (~50mg). Caffeine is found in coffee, tea, many sodas, many aspirin products, and chocolate. Some evidence suggests that increased amounts of caffeine in pregnancy may increase the risks of miscarriage, preterm delivery, and low birth weight.
Sexually transmitted diseases
Chlamydia and Gonorrhea infections can be symptomless and cause damage to the fallopian tubes resulting in blockage or hydrosalpinx.
Being over or underweight can affect fertility. Ovulation irregularity and PCOS are more common among heavier women. A modest reduction in body weight can restore normal ovulation in many cases. A BMI of less than 37 is recommended for fertility treatment, and required for IVF. Calculate your BMI. Underweight women (those with a BMI <19) can have fertility problems too, including irregular or absent ovulation and menses.