What to Know About Fertility at Every Age

March 25, 2026

Happy parents sitting on a couch with their baby boy

People are waiting longer to have children. The average age of first-time parents is now 30 for women and 31 for men, with many more couples having babies into their late 30s and beyond. While there are benefits to starting a family later, there are also challenges that can occur because of aging.

Infertility: A Couples Issue

When a couple can’t get pregnant, it can be the result of female factors, male factors or factors that can’t be identified. When a couple is having trouble conceiving, the cause is equally likely to be because of the man or the woman. Infertility is unexplained in roughly 15% of cases.

“It’s surprising to many patients that male factors are found in at least 40% of infertility patients, so a full evaluation of both people is necessary in most cases,” says Rebecca Flyckt, MD, Division Chief of Reproductive Endocrinology & Infertility at University Hospitals and Medical Director of the UH Fertility Center.

How Female Fertility Changes Over Time

Girls are born with 1 to 2 million eggs. By puberty, about 300,000 remain, and the number and quality of eggs continues to decline until the last egg is released during the menopause transition.

A woman’s chances of getting pregnant depends on many factors, including:

Quantity and quality of eggs
Hormonal and anatomical factors
Overall health
Lifestyle factors

“One of the most common causes of infertility is natural ovarian aging, which means over time, the number of available eggs decreases and egg quality declines, making a healthy pregnancy less likely,” says Dr. Flyckt.

Additional factors that contribute to infertility in women include:

Endometriosis (especially severe endometriosis)
Fibroids
Prior ovarian surgery
Polycystic ovarian syndrome
Hormonal conditions that affect ovulation or cause irregular periods
Serious pelvic infections, especially sexually transmitted diseases
Blocked or damaged fallopian tubes
Cancer treatments

How Male Fertility Changes Over Time

Boys start producing sperm at puberty and can continue producing it throughout their lifetime, but their fertility is also affected by age. “Sperm quality slowly declines, starting in the mid-30s, but most men are still able to father children well into later life,” says Dr. Flyckt.

Like women, men experience hormonal changes with age, including a decline in circulating testosterone levels. Higher paternal age has been associated with lower overall pregnancy rates and increased miscarriage rates, with or without fertility treatments and regardless of the age of the female partner.

Factors that affect fertility in men include:

Age, especially after age 40
Being overweight or obese
Physical problems in the testicles
Blockages in the tubes that carry sperm
Erectile dysfunction, ejaculation issues and other sexual problems
Varicocele (swelling in the veins that drain the testicles)
If the testicles have experienced trauma
Certain illnesses, infections and medical conditions
Certain medications, medical treatments and surgeries
Exposure to radiation or environmental toxins
Increases in the temperature of the testicles through use of saunas, hot tubs or wheelchairs
Lifestyle factors, like using tobacco, marijuana, alcohol or steroids

A Timeline of Fertility by the Decade

Typically, by the late teenage years, the chances of conceiving for both men and women are very high and remain so for the next 10 to 15 years.

20s – High Fertility

The most fertile years for women are typically their late 20s through early 30s, says Dr. Flyckt. “During this time, the chance of conceiving each month is the highest, and the risks of miscarriage and chromosomal abnormalities in the baby are the lowest.” Men also tend to be most fertile throughout their 20s.
30s – Fertility Starts to Change

Fertility tends to stay relatively stable through the early 30s. Around age 32, it starts slowly declining. Fertility dips more rapidly in the later 30s, with a tipping point for most women occurring around 37 years old, says Dr. Flyckt. Not only is it harder to get pregnant, there is also an increased risk of miscarriage and other complications. “This happens because women are born with all of their eggs, and the number and quality both decrease with age.”

Men also continue to have high fertility in their early 30s. Their fertility begins to decrease around age 35. Sperm count, quality and motility may begin to decline, making it harder to conceive and increasing the risk of miscarriage.
40s – More Challenging to Have a Baby

Many women can still get pregnant in their early 40s, but they often face challenges. By the time a woman enters perimenopause her chances of getting pregnant begin decreasing dramatically. The transition can be a confusing time and can begin as early as the mid- to late 30s for some women, or the 40s or early 50s for others.

“Most women don’t know that perimenopause can last for five to 10 years before you start missing periods or stopping altogether,” says Dr. Flyckt. “During this time, changes in a woman’s eggs can make it difficult to get pregnant, even with assistance. By the time women reach 45, the chance of pregnancy per month is less than 5% and the chance of miscarriage if a woman becomes pregnant is up to 50%.”

Male fertility continues to decline in the 40s as well, but the changes are more gradual. After 45, semen volume drops significantly. Additionally, decreasing levels of testosterone can lead to issues with sexual function that also make it more difficult to conceive. “There is no specific age cutoff where male fertility suddenly stops, although changes in sperm counts and motility become more pronounced after age 40,” she says. Fertility treatments like IVF may help, but age-related fertility challenges can’t always be overcome, even with cutting-edge technologies.
50s – Low to No Fertility

By the time women are in their early to mid-50s, the majority have entered menopause. A minimal number of eggs remain and the quality is also likely to be significantly diminished. The chances of pregnancy, even with IVF, are very low and the risk of miscarriage and other abnormalities is high.

While men can still conceive in their 50s and beyond, their fertility and the quality of their sperm, continues to decline. From the mid-40s to mid-50s, sperm volume decreases by about one-third. Sexual function also diminishes with advancing age for many men. If conception does occur at this stage of life, there may be a greater risk of miscarriage, as well as genetic abnormalities.

Lifestyle Factors That Can Support Fertility

While some factors that affect your chances of getting pregnant are beyond your control, there are many positive steps you can take that may help improve your chances. “Everyday habits play an important role in fertility,” says Dr. Flyckt. Two of the most important steps people can take to support natural fertility are:

Maintain a healthy weight. “Reaching a healthy body weight (whether starting overweight or starting underweight) can affect hormone balance and ovulation,” says Dr. Flyckt.
Avoid smoking. “Smoking tobacco can damage eggs and sperm and can affect their ability to come together in the reproductive tract,” she says.

You can also support your reproductive health by:

Limiting alcohol
Taking folic acid
Eating a balanced diet rich in fruits, vegetables, whole grains and healthy proteins
Keeping caffeine to a minimum
Not overdoing it with vigorous exercise
Steering clear of toxins
Preventing sexually transmitted infections
Managing stress
Getting plenty of quality sleep

Preserving Your Fertility

If you’d like to have children in the future but aren’t ready right now, fertility preservation can give you more flexibility. This option can be helpful for people who don’t have a partner during their peak fertility years, for those who need medical treatment that may impact their fertility, or for LGBTQIA+ people who want to keep their options open as they consider different paths to building a family.

A variety of fertility preservation options exist for men and women, including:

Freeze your eggs. “Egg freezing works best when done earlier, with an ideal age around 32 to 33 – before egg number and quality decline more rapidly – though it can be successful later,” says Dr. Flyckt. “Blood tests that estimate ovarian reserve can help guide timing, but they can’t perfectly predict future fertility.”
Freeze your sperm. “There is no ideal age for sperm freezing,” she says. “Although this approach is gaining popularity, it’s not clear how or when sperm freezing is most beneficial for otherwise healthy men.”
Freeze embryos. It’s also possible to remove eggs from the ovaries, fertilize them in a lab setting and freeze the embryos for future use. Embryos can be thawed and transferred back into the same person or another person. More than 95% of frozen embryos survive the preservation and thawing process. Chances of pregnancy are strongly influenced by the maternal age at the time of the egg retrieval. Embryos created from eggs retrieved at age 35 or younger tend to have the best outcomes.

While assisted reproductive technologies have come a long way in recent years, Dr. Flyckt shares a note of caution. “If I could dispel one myth about fertility, it would be that women are fertile as long as they are still getting their periods regularly,” says Dr. Flyckt. “This can create a false sense of security and delay family planning decisions until fertility has already declined significantly.”

“Women and couples often come to us expecting IVF to be the ‘cure’ for infertility,” says Dr. Flyckt. “It can often help, but the combination of age and changes in egg quantity and quality may mean that the success rates remain very limited, even when we use the most advanced technologies available.”

Another persistent myth is that infertility is usually the result of a woman’s inability to get pregnant or carry a baby to term. In fact, research shows that while sperm count and quality decline more gradually than egg quantity and quality, fertility challenges are caused by both men and women at a similar rate.

The Advantages of Having Kids Later in Life

While your chances of conceiving and having a healthy pregnancy may be greater when you’re younger, the timing may not be right. Many young adults are still building their careers, shoring up their finances and pursuing other life goals in their 20s and early 30s.

There are advantages to getting pregnant later in life, as many couples are finding out. Starting a family later can offer more stability and security, and you have more time to mature and grow as a person – and as a couple. Studies have shown that children born to older parents may perform better in school, face fewer social, behavioral and emotional problems and end up being healthier. Some studies suggest having children later in life may even help you live longer.

Dr. Flyckt’s commentary was supported by additional data gathering by REI fellow Ariya Mobaraki, MD.