Fertility

Understanding fertility, in plain terms

Fertility is simply the ability to conceive, and it depends on a combination of factors: egg and sperm quality, regular ovulation, open fallopian tubes, a receptive uterus, and overall health. For most couples trying to conceive, the timing of intercourse relative to ovulation matters more than almost anything else, which is why fertility and ovulation tracking so often go hand in hand.

How age factors in

People with ovaries are born with all the eggs they will ever have, and both the number and quality of those eggs decline over time, more noticeably after age 35. This is one of the most well-documented factors in fertility, but it is not the only one, and it does not mean conception becomes impossible, just statistically less likely per cycle. Male fertility also declines with age, though more gradually, as sperm quality and quantity can be affected by age and health over time. For a deeper look at how age affects the odds at different stages, see Age and Fertility.

When to see a specialist

ACOG and most reproductive specialists recommend evaluation after 12 months of regular, unprotected intercourse without conception if you are under 35, or after 6 months if you are 35 or older. See a specialist sooner if you have irregular or absent periods, a history of pelvic infections or endometriosis, known low sperm count, or if you or a partner have had cancer treatment that could affect fertility. A specialist can run tests to identify or rule out common causes and lay out a range of options from there. See When to See a Fertility Specialist for how that first appointment typically goes.

Lifestyle factors that make a real difference

Maintaining a moderate body weight, not smoking, limiting alcohol, managing stress, and treating underlying conditions like thyroid disorders or diabetes can meaningfully support fertility for many people. These changes will not reverse age-related decline or fix conditions like blocked tubes, but they are a reasonable, evidence-supported starting point before or alongside medical evaluation. See Fertility Lifestyle Factors for specifics on diet, exercise, and habits worth adjusting.

Practical checklist while trying to conceive

When to call a provider sooner

Do not wait out the standard timelines if you have irregular or absent periods, very painful periods that could suggest endometriosis, a history of pelvic inflammatory disease, two or more prior miscarriages, or if either partner has a known fertility-affecting condition. These situations warrant earlier evaluation rather than waiting the full 6 or 12 months.

How these guides fit together

Start with the age and fertility guide to understand the biological backdrop, use the lifestyle factors guide for what is within your control day to day, and turn to the specialist guide once you have hit the point where medical evaluation makes sense.

Frequently asked questions

At what age does fertility start to decline?

Fertility gradually declines through the 30s and drops more noticeably after age 35 for people with ovaries, mainly due to a decrease in egg quantity and quality. Male fertility also declines with age, though more gradually.

When should I see a fertility specialist?

Generally after 12 months of trying without success if you are under 35, or after 6 months if you are 35 or older. See a specialist sooner if you have irregular cycles, a known reproductive health condition, or a partner with a known fertility issue.

Can lifestyle changes really improve fertility?

For some people, yes. Maintaining a moderate weight, not smoking, limiting alcohol, and managing chronic conditions like diabetes or thyroid disorders can meaningfully support fertility. They cannot reverse age-related decline or fix every underlying condition, but they are a reasonable place to start.

For more on fertility evaluation timelines, see ACOG's guidance on evaluating infertility.