Most couples who are actively trying to conceive will get pregnant within 12 months. In her early to mid-20s, a woman has a 25 to 30 percent chance of conceiving in any given menstrual cycle, which means that even under ideal conditions, it often takes several months. That per-cycle probability drops with age, and lifestyle factors can shift the timeline further.
The Per-Cycle Odds by Age
Your age is the single biggest factor determining how quickly you’ll conceive. A woman in her early to mid-20s has roughly a 25 to 30 percent chance of getting pregnant each month. While specific mid-30s data varies, fertility declines noticeably through the 30s. By age 40, the chance of conceiving in any single cycle drops to around 5 percent.
In practical terms, that means a couple in their mid-20s might conceive within three or four months of trying, while a couple where the woman is 40 could need a year or longer for the same outcome. These are averages. Some people conceive on the first try, and others take much longer without anything being clinically wrong.
Male age matters too, though the effect kicks in later. Partners of men aged 45 or older take longer to conceive and face a higher risk of miscarriage. These effects tend to develop during a man’s 40s, especially when other chronic health conditions are present.
Your Fertile Window and Timing
Conception can only happen during a narrow stretch of each cycle called the fertile window. An egg survives about 12 to 24 hours after ovulation, but sperm can live inside the reproductive tract for three to five days. That creates a fertile window of roughly six days: the five days before ovulation and the day of ovulation itself.
The best approach is straightforward. Intercourse every one to two days during the fertile window gives you the highest pregnancy rates. But you don’t need to be that precise. Having sex two to three times per week throughout the cycle produces nearly equivalent results. One large study found that cycle-by-cycle conception rates were similar whether couples had intercourse daily, every other day, or even every three days during the fertile window. The only scenario that clearly lowered the odds was having intercourse just once during that window. More frequent sex doesn’t hurt your chances either, so there’s no reason to hold back.
Coming Off Birth Control
If you’ve recently stopped hormonal contraception, the type you were using affects how quickly your fertility returns. A large study from Boston University tracked the timeline across different methods. Women who used oral contraceptives or vaginal rings waited an average of three menstrual cycles before conceiving. Patch users averaged about four cycles. The longest delay came from injectable contraceptives (the shot), which suppress ovulation more deeply: women using injectables waited an average of five to eight cycles before becoming pregnant.
These are averages, not guarantees. Some women ovulate within weeks of stopping any method, while others take longer to resume regular cycles. If your period hasn’t returned within a few months of stopping birth control (longer for injectables), that’s worth bringing up with your doctor.
Factors That Can Slow Things Down
Smoking is one of the most well-documented fertility reducers. Women who smoke have higher rates of infertility, lower per-cycle conception rates, and longer times to pregnancy compared to nonsmokers. A large study evaluating nearly 15,000 pregnancies found that active smoking was associated with increased failure to conceive within both 6 and 12 months of trying. In assisted reproduction, smokers require nearly twice as many treatment cycles to conceive as nonsmokers. Each year a woman spends smoking is associated with a 9 percent increase in the risk of an unsuccessful fertility treatment cycle.
Body weight plays a role at both extremes. Being significantly underweight or overweight can disrupt ovulation, extending the time it takes to conceive. Weight-related hormonal shifts can make cycles irregular or stop ovulation altogether, which is one of the more common and correctable causes of delayed conception.
Other factors that can extend the timeline include heavy alcohol use, high stress levels, untreated thyroid disorders, and conditions like polycystic ovary syndrome or endometriosis. For men, factors like obesity, heavy drinking, and excessive heat exposure (from saunas or tight clothing) can reduce sperm quality.
When the Timeline Suggests a Problem
Infertility is formally defined not as a permanent condition but as a threshold for when testing makes sense. For women under 35, the guideline is to seek evaluation after 12 months of regular, unprotected intercourse without conceiving. For women 35 and older, that window shortens to 6 months. For women over 40, more immediate evaluation may be appropriate given the steeper decline in per-cycle odds.
These timelines exist because conception is a numbers game even when everything is working perfectly. A 25 percent per-cycle chance still means a 75 percent chance of not conceiving in any given month. Over several months, though, those odds accumulate. About 80 percent of couples conceive within six months of trying, and roughly 90 percent within a year. If you’ve crossed the recommended threshold for your age without success, a fertility evaluation can identify whether something specific is interfering or whether you’re simply on the longer end of normal.