We built this calculator to provide information about how long it takes couples to conceive, on average. It's based on our review of more than 30 scientific papers. Even with daily intercourse and a normal menstrual cycle, there is still only about a one in four chance of conceiving each month. And depending on your age, your cycle, and certain lifestyle factors, your chances of conceiving each month may be lower. All of this is to say that you needn't be alarmed if you don't get pregnant on your first month trying. For many couples, it's perfectly normal to take many months to conceive. Note: this calculator is designed to predict probability of conception resulting in a live birth (one third of all pregnancies end in miscarriage).
Fertility in women peaks between the ages of 20-24, then very slowly declines until age 30-32, then declines progressively.
Being underweight and overweight can both negatively impact fertility. Being underweight can lead to anovulatory cycles. Being overweight is associated with menstrual dysfunction, decreased fertility, and increased risks of miscarriage.
Your BMI is:
A normal cycle length is usually between 26-32 days. Shorter cycles can be associated with decreased fertility. Most of the time, this is due to a short follicular phase related to ovarian aging. A small proportion of short cycles may reflect shortened luteal phases.
Irregular menstrual cycles are related to a reduced conception rate and to reduced survival of the pregnancy. This might be due to disturbances in ovulation, conception, implantation, or sustained pregnancy. Women who have menstrual cycles of variable length perhaps are candidates for infertility evaluation at an earlier stage than women with regular cycles.
The fertile window lasts about six days, ending on the day of ovulation. The two days before and the day of ovulation are the most fertile. After ovulation, there is a rapid drop in conception probability.
Assuming no special timing with regard to ovulation, daily intercourse or intercourse every other day results in the highest probability of conception. At lower frequencies the rate of conception drops more rapidly; untimed intercourse averaging once per week results in a 3-fold decrease in probability of conception.
Smoking has well-known adverse impact on both fertility and pregnancy. The prevalence of infertility is higher, fertility is lower, and the time to conception is longer in smoking compared to non-smoking women. The effects of second-hand smoke are only slightly less than those of active smoking by either partner.
Other forms of substance abuse also can adversely affect fertility. Marijuana inhibits the secretion of GnRH and can suppress reproductive function in both women and men. In women, marijuana use can interfere with ovulatory function.
Heavy alcohol consumption in women may decrease fertility. In both women and men, even modest amounts of alcohol consumption have been associated with lower pregnancy rates in IVF cycles.
Moderate caffeine ingestion (≤ 300 mg daily; two standard beverages) appears not to have any adverse effects on fertility. Higher levels of consumption may delay conception or increase the risk of pregnancy loss.
Stress significantly reduces the probability of conception each day during the fertile window.
In lean women, increasing vigorous physical activity can delay time to pregnancy. In overweight and obese women, any type of physical activity might improve fertility. Moderate physical activity is associated with a small increase in fertility regardless of BMI.
Pregnancy rates decrease and time to conception increases as male age increases. The cause of the decline in fertility is not well known: male aging could lead to a decrease in sperm quality and morphological changes in the testes. The effect is rather small before age 45-50.
Evidence strongly suggests that fertility is lower in both men and women who smoke. The prevalence of infertility is higher, fertility is lower, and the time to conception is longer in smoking than in non-smoking women, and the effects of second-hand smoke exposure are only slightly less than those of active smoking by either partner.
Other forms of substance abuse also can adversely affect fertility. Marijuana inhibits the secretion of GnRH and can suppress reproductive function in both women and men.
Heavy alcohol consumption in men has been associated with decreased semen quality and impotence. In both women and men, even modest amounts of alcohol consumption have been associated with lower pregnancy rates in IVF cycles.
Heavy caffeine intake (> 700mg/day) in male partners is related to decreased fertility.
Overweight and especially obese men are more likely to have abnormal semen parameters, which can adversely affect fertility.
Their BMI is:
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Less Than or Equal to 17
Couples who have been trying to conceive for six months or more will, on average, have lower cycle viability and thus a lower probability of conception.
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