How Does Age Affect Fertility?

Fertility is influenced by many factors such as hormones, overall health, and genetics, but age remains one of the most important predictors of someone’s ability to conceive. Whether you’re trying to conceive now or planning for the future, understanding how fertility changes with age can help you make informed decisions.

Why Age Matters:    

People are born with all the eggs they will ever have - around 1-2 million at birth. By puberty, that number drops to about 300,000, and only a fraction will ever mature. Over time, the number of eggs declines and the quality of remaining eggs decreases, which makes conception more challenging and increases the risk of miscarriage.

Sperm quality also changes with age, though more gradually. DNA fragmentation, motility, and semen volume tend to decline in the late 30s and 40's.

Fertility by Age:

• In Your 20s

  • Peak fertility: conception per cycle is highest

  • Lower rates of miscarriage and chromosomal abnormalities

  • Best success rates with treatments like IUI and IVF
     

• Early 30s (30–34)

  • Fertility remains strong, though it begins a slow decline

  • Most people in this range still conceive within a year

  • Egg quality starts to decrease gradually
     

• Mid to Late 30s (35–39)

  • Around age 35, the rate of egg loss accelerates

  • Higher rates of aneuploidy (chromosomal abnormalities) and miscarriage

  • More difficulty conceiving naturally and lower IVF success rates

  • Fertility specialists often recommend earlier evaluation (after 6 months of trying)
     

• 40 and Beyond

  • Fertility drops more rapidly after age 40

  • Lower ovarian reserve and higher chance of abnormal eggs

  • Success rates for natural conception and IVF decline significantly

  • However, many individuals do still conceive (especially with treatment or the use of donor eggs)
     

How Age Affects Men

• While the decline is slower, age can impact:

  • Sperm motility (movement) and morphology (shape)

  • DNA integrity

  • Time to pregnancy

  • Risk of certain conditions in offspring

  • Evaluation is still important (fertility is always a two-partner equation)

 

How We Evaluate Age-Related Fertility

• A fertility work-up may include:

  • Ovarian reserve testing

  • Ovulation assessment

  • Semen analysis

  • Ultrasound for uterine and ovarian health

  • Age is one piece of the puzzle, but personal medical history, cycle regularity, and lifestyle also play major roles

 

What You Can Do

• Even though age affects fertility, there are proactive steps you can take:

  • Get evaluated early if you’re over 35 or have known reproductive health concerns

  • Track ovulation to time intercourse or inseminations more effectively

  • Consider supplements, optimizing sleep, managing stress, and maintaining overall health

  • Explore fertility preservation options (egg or embryo freezing), especially if you’re not ready to conceive yet

 

Age impacts fertility, but it doesn’t define your journey. Many people conceive in their late 30s and 40s - some naturally, some with support from a fertility specialist. The most empowering step is understanding your reproductive health early and creating a plan that aligns with your goals.

If you have questions about your fertility at any age, our team at Denver Fertility Care is here to help, contact us today.

 

References:

Having a Baby After Age 35: How Aging Affects Fertility and Pregnancy | ACOG

Does My Age Affect My Fertility? patient education fact sheet | ReproductiveFacts.org