How Age May Affect Fertility

Dreaming of having a baby girl or boy of your own? Once upon a time, having a baby in your 20s was a rite of passage for the majority of American women. But since that time—around 1970, to be precise—more and more aspiring parents are delaying having kids until later in life.

But while trends in childbirth have shifted, biological fertility hasn’t: it’s still true that female fertility peaks in your 20s. However, the development of fertility sciences and assisted reproductive technologies have given people more choices regarding the when of starting a family.

Today, the National Institutes of Health estimate that around 20% of American women give birth for the first time at 35 years old. No matter the age you start giving serious consideration to the idea of having children, understanding how age interacts with fertility and human reproduction can provide key insights into the journey you’re about to begin.

Fertility Through the Decades: What to Expect

Female fertility can be thought of as running on two timelines:

• Month-to-month – Your monthly reproductive cycle can be divided into four phases: the follicular phase, ovulation, luteal phase, and menses. Each phase depends on an influx or reduction of hormones, some of the most crucial being estrogen and progesterone.
• The human lifespan – The term “biological clock” is often used to describe female fertility from puberty to menopause and the changes it undergoes along this trajectory. However, the use of the term has been questioned due to the stress it can put on women to have children at the height of their fertility. That said, female fertility naturally decreases as one gets older.

While these patterns are the norm for the vast majority of women, it’s important to acknowledge that everyone’s bodies, genetic inheritance, and fertility experience are different. Some people may encounter hormonal issues or fertility challenges early in life. Others may decide to start a family in their 40s and get pregnant almost immediately.

Plus, thanks to advancements in reproductive medicine and technology, there are numerous routes to having a child—and age doesn’t have to be a prohibitive factor in doing so. Many women have questions about what conception can look like for them – find answers to those questions (like tips to get pregnant or the best sex positions to get pregnant) right here on our blog.

That said, it’s helpful to understand what female fertility looks like through the ages and how it can impact your experience getting pregnant and having a healthy pregnancy.

Fertility in Your 20s

In biological terms, women experience peak fertility in their 20s. This is due to several factors:

• A voluminous ovarian reserve – Most women have between 300,000 and 400,000 eggs (or oocytes) in their ovaries by the time they reach puberty. By their 20s, this number diminishes to 150,000 to 300,000—but these eggs are considered some of the highest quality in the lifespan.
• Optimal reproductive hormones – Key reproductive hormones needed for conception and pregnancy include estrogen, progesterone, and LH (luteinizing hormone). These are typically at their peak for women in their 20s and contribute to a relatively stable reproductive cycle. Because of this, women in their 20s have around a 25% chance of conceiving in just 1 menstrual cycle.
• Lower likelihood of complications – Because your 20s are a time of high egg quality and hormonal health, people who get pregnant at this age have a lower risk of fetal health and pregnancy complications.

Fertility in Your 30s

In most people, fertility begins to decline at the age of 32, with a slightly more dramatic drop between 35 and 37. This is due to:

• A decline in the ovarian reserve
• A decline in oocyte quality

The most prominent marker of depreciated egg quality is a chromosomal abnormality, which can make it more difficult to conceive a viable pregnancy. Additionally, changes in hormone levels can result in cycle irregularity, which can make it more difficult to conceive.

Even so, odds remain on your side if you’re pursuing pregnancy in your 30s, especially before age 37. Your healthcare provider will likely administer more screenings to rule out any heightened risks of pregnancy at this age.

Fertility in Your 40s (and Beyond)

By your 40s, most women will experience a significant decline in fertility. Natural conception may be more difficult at this stage due to:

• A much smaller ovarian reserve (typically between 5,000 to 10,000 oocytes)
• Lower-quality eggs, an estimated 90% of which may have chromosomal abnormalities
• Changes in your uterus, such as a thinner uterine wall and reduced blood supply (this can make it harder for a fertilized egg to implant)

Though it can be substantially harder to conceive in your 40s, it’s by no means impossible—especially with the introduction of fertility treatment and ARTs, or assistive reproductive technologies.

Many people choose to wait until their 40s to start a family due to a sense of stability they lacked in prior decades (don’t worry—we’ll get to the benefits of being a 40+ parent later!).

What’s the best age to have a baby?

Yes, women are most fertile in their 20s and early 30s, and they have a lower risk of fetal and maternal health complications. However, the choice to have a baby isn’t strictly scientific—it’s personal, practical, and circumstantial.

Countless factors are worth considering when debating whether or not to have a child, including:

• Your finances
• Your sense of personal and/or professional fulfillment
• Your partnership, relationships, support systems, and community
• Your lifestyle
• Your willingness to take on the responsibility of caring for a newborn
• Your health
• Your life circumstances (e.g. where you live)

When it comes down to it, the best age to have a baby (and a successful pregnancy) is whenever you feel ready. Having a child is both a tremendous joy and a life-altering responsibility, and you deserve to have the resources you feel you need to make that decision. You can learn more about fertility and how to prepare your body for pregnancy on our blog.

How does age impact male fertility?

Female fertility is only half of the picture if you’re starting a family with a partner. In around ⅓ of cases, male infertility can make it more difficult to conceive a baby.

Though men don’t run on a monthly reproductive-hormonal cycle, paternal age impacts their ability to bear children as well. Age expresses itself in male fertility in:

• Reduced semen volume – The amount of semen a man produces when he ejaculates tends to decline with age.
• Reduced sperm concentration – Men’s sperm count trends downward as they get older.
• Reduced sperm motility – Over time, sperm cells may have a harder time moving out of the testes and epididymis and ultimately reaching an egg in the fallopian tube.
• Abnormal morphology –As a man’s age advances, their sperm may deviate from the normal morphology—essentially, the shape and structure of a sperm cell.
• Degraded DNA – As a man gets older, DNA in sperm cells may undergo fragmentation, making them less viable to fertilize an egg—and even if an egg is fertilized, research shows an increased risk of single gene disorders.

In addition to the concrete biological changes the male reproductive system undergoes over time, getting older simply introduces other factors that can wear on male fertility. This includes increased exposure to environmental toxins as well as ED (erectile dysfunction), decreased libido, and, in heterosexual couples, a tendency to be partnered with older women.

What to Know About Having a Child Later in Life

There are many myths and misconceptions surrounding age and fertility that deserve clarification—especially for those who want to become parents later on in life.

Many people are familiar with the main points of caution when it comes to older parenthood, including:

• Health risks – For women in particular, elevated age corresponds with a riskier pregnancy. Babies may have a higher likelihood of chromosomal abnormalities or preterm birth. Meanwhile, mothers are more likely to develop health concerns and pregnancy complications like gestational diabetes or hypertension. Recovering after the postpartum stages may also be more challenging.
• Lifespan or energetic concerns –Taking care of a child requires a significant amount of energy from their first weeks of life to their teenage years. Caretaking roles typically last until kids are able to take care of themselves—though, even after your child leaves home, the role of “parent” is one you’ll never fully retire.

These can be major points of reckoning for those concerned they won’t be able to meet their child’s needs at a later age. However, many older parents are more than satisfied with their decision to have kids later.

Some frequently cited advantages include:

• Having greater financial stability than they had in their 20s and 30s
• Having considerably more life experience and wisdom to impart to their children
• Having more stable relationships and support systems to help share the responsibilities of raising a child
• Having greater emotional resilience and patience, creating a nurturing environment in which to raise a child

Regardless of where you are in the decision-making process, remember that the choice to have a child is one of life’s biggest—and it’s entirely up to you. Curiosity and self-compassion are all you need to begin your journey, no matter where it takes you.

Start Your Pregnancy Journey Earlier with SneakPeek®

Regardless of when you decide to have children, you can get to know your baby ahead of time with the SneakPeek Early Gender DNA Test®. This easy-to-use at-home test allows expectant parents to learn their baby’s predicted sex as early as 6 weeks into their pregnancy, with over 99% clinically proven accuracy and DNA-based results.

More than 1 million parents have used SneakPeek to announce their future baby’s sex earlier than ever. Discover why SneakPeek is the #1 OBGYN-recommended at-home early gender test. Order yours today.

Editorial Policy

At SneakPeek, our commitment is to provide accurate, up-to-date, and reliable information to empower our readers. Our content is thoroughly researched, reviewed by medical experts, and fact-checked to ensure its credibility. We prioritize the well-being and education of our readers, and our editorial policy adheres to the highest standards of integrity and accuracy in all our articles.

Sources:

1. Centers for Disease Control. American Women Are Waiting to Begin Families. https://www.cdc.gov/nchs/pressroom/02news/ameriwomen.htm
2. National Institutes of Health. Having Kids Later in Life. https://newsinhealth.nih.gov/2022/07/having-kids-later-life
3. Healthline. What’s the Connection Between Your Biological Clock and Fertility? https://www.healthline.com/health/biological-clock-women
4. Healthline. What’s the Best Age to Get Pregnant? https://www.healthline.com/health/pregnancy/best-age-to-get-pregnant#20s
5. Verywell Health. How Many Eggs Do Women Have During Their Lifetime? https://www.verywellhealth.com/how-many-eggs-does-a-woman-have-8413881#toc-counting-female-eggs-before-and-after-birth
6. Parents. Your Odds of Getting Pregnant at Every Age. https://www.parents.com/getting-pregnant/trying-to-conceive/up-your-chances-of-getting-pregnant-at-every-age/#toc-chances-of-getting-pregnant-in-your-early-20s-20-to-24
7. Cleveland Clinic. Infertility. https://my.clevelandclinic.org/health/diseases/16083-infertility
8. National Library of Medicine. Fertility and the Aging Male. https://pmc.ncbi.nlm.nih.gov/articles/PMC3253726/
9. Mayo Clinic. Pregnancy after 35: Healthy pregnancies, healthy babies. https://www.mayoclinic.org/healthy-lifestyle/getting-pregnant/in-depth/pregnancy/art-20045756
10. Best Life. 40 Reasons You’re a Better Parent After 40. https://bestlifeonline.com/better-parent-over-40/
11. Cleveland Clinic. Menstrual Cycle. https://my.clevelandclinic.org/health/articles/10132-menstrual-cycle
12. NIH. Reproductive genetics and the aging male. https://pmc.ncbi.nlm.nih.gov/articles/PMC6030011/