Women are born with all the immature egg follicles they will ever have approximately 1 to 2 million. By the onset of menstruation, around age 12, this number decreases to about 300,000 to 500,000.
Each menstrual cycle leads to the loss of several hundred eggs, though only the healthiest follicles fully mature. The rest are naturally broken down and absorbed by the body. Unlike women, men continue producing new sperm throughout most of their adult lives.
As women age, the number of available follicles steadily declines, reducing the chances of producing strong, viable eggs for Fertility Journey. During adolescence and early adulthood, the egg supply is abundant. However, by the late 30s and early 40s, the reserve diminishes sharply with an average of just 25,000 eggs remaining at age 37. Ironically, this is also the period when many people begin considering parenthood.
In fact, the current average age for first-time mothers is 27.5 years, a figure that has been steadily rising as more individuals delay starting a family.
With this shift, it becomes increasingly important to understand how postponing pregnancy can influence fertility outcomes.
Read More: The Ultimate Guide to Dressing for Your Body Shape
Ages 18 to 24
From a purely biological perspective, the late teens through early 20s represent the optimal window for fertility. During this stage, the body’s strongest ovarian follicles mature first, which means the eggs released are more likely to be of high quality.
Conceiving during this age range can reduce the likelihood of:
- Birth defects
- Chromosomal abnormalities
- Certain fertility challenges later in life
That said, pregnancy at this stage is not entirely risk-free.
Fertility potential, often referred to as the fecundity rate, naturally rises and falls throughout a woman’s life. It is at its peak during these younger years, but by age 30, the average monthly chance of natural conception drops to about 20%.
Interestingly, while fertility rates among women aged 18 to 24 have declined over the past several decades, there has been a slight increase in fertility among women in their 30s and 40s, reflecting the growing trend of postponing parenthood.
Ages 25 to 30
Fertility does gradually decline with age, but in the late 20s, the chance of conceiving naturally remains relatively strong and consistent.
Healthy couples under age 30 are able to conceive within the first three months of trying about 40% to 60% of the time. During these years, the ovarian reserve still provides a plentiful supply of eggs, maintaining favorable conditions for pregnancy.
If conception does not occur after several months of trying, it’s advisable to consult a doctor. While most couples in this age group can achieve pregnancy without medical assistance, professional guidance can help identify or rule out potential issues and provide reassurance during the process.
Ages 31 to 35
In the early 30s, fertility remains relatively strong, and many eggs are still of good quality. However, this is the stage when the natural decline in fertility begins to become more noticeable. By this age range, women are about half as fertile as they were in their early 20s.
That does not mean pregnancy is out of reach. Many women successfully conceive and carry healthy pregnancies in their 30s. In fact, according to the National Institutes of Health, 1 in 5 women have their first child after age 35.
Still, infertility challenges become more common during this decade compared to the 20s, making it important to be aware of potential risks and to seek medical support if conception takes longer than expected.
Ages 35 to 40
Fertility continues to decline significantly during the mid-to-late 30s, making conception more challenging. By age 40, a woman’s chance of becoming pregnant naturally falls to less than 5% per cycle, according to the American Society for Reproductive Medicine. The American College of Obstetricians and Gynecologists (ACOG) estimates the chance to be slightly higher, around 10% per cycle at age 40.
This drop in fertility often coincides with the stage of life when many individuals are actively trying to start families. However, it is also the period when the risk of chromosomal abnormalities in eggs increases sharply, raising the likelihood of miscarriage or abnormal pregnancy outcomes. Each passing year beyond 35 further compounds these risks.
Ages 41 to 45+
In recent years, childbirth among women over 40 has become the fastest-growing demographic trend, largely due to the decision to delay parenthood. While more individuals are giving birth in their late 30s and early 40s, the overall percentage of births in this age group remains lower compared to younger women, primarily because natural conception becomes significantly more difficult after 40.
By this stage, the ovaries have exhausted most of their follicles, and the body is gradually preparing for menopause. Each cycle reduces the remaining supply, and by the early 50s, very few, if any, follicles remain.
Pregnancies at this age are associated with a higher risk of complications for both parent and child. Babies are more likely to experience chromosomal abnormalities and other birth irregularities, while miscarriage rates increase sharply. A 2019 population-based study from Norway found that women over 45 faced a 53% risk of pregnancy loss, compared with just 10% among women ages 25 to 29.
For the parent, advanced maternal age also increases the risk of serious conditions such as:
- Gestational diabetes
- Hypertension
- Preeclampsia
Frequently Asked Questions
At what age is fertility at its peak for women?
Fertility is at its highest between ages 18 to 24, when egg quality and ovarian reserve are strongest.
How quickly can couples in their 20s expect to conceive?
Healthy couples under 30 have a 40–60% chance of conceiving within the first three months of trying.
Does fertility decline significantly after 30?
Yes. By age 30, the monthly chance of natural conception is about 20%, and fertility steadily declines thereafter.
Is it still possible to conceive naturally in your mid-30s?
Yes. Many women successfully conceive in their 30s, though fertility is about half of what it was in the early 20s.
What are the chances of pregnancy at age 40?
By age 40, the natural chance of conceiving is less than 5–10% per cycle, depending on health and other factors.
Why is pregnancy riskier at older ages?
With age, eggs are more likely to have chromosomal abnormalities, increasing the risks of miscarriage, birth defects, and complications.
Can fertility treatments help women over 40?
Yes. Treatments such as IVF, donor eggs, and fertility medications can improve the chances, though success rates are lower than at younger ages.
What lifestyle factors support fertility at any age?
Maintaining a healthy weight, balanced diet, regular exercise, stress management, and avoiding smoking/alcohol can help preserve fertility.
How does male fertility compare to female fertility?
Men continue producing sperm throughout life, though sperm quality gradually declines with age, especially after 40.
Conclusion
Fertility is a natural process that changes with age, influenced by both the number and quality of eggs available. While women are most fertile in their late teens and 20s, many still conceive successfully in their 30s and beyond. However, fertility declines more sharply after 35, and pregnancy risks increase with age, especially after 40.
Understanding these changes empowers individuals to make informed decisions about family planning. Whether choosing to start earlier, delay parenthood, or explore fertility treatments, being aware of the biological timeline helps ensure that choices align with personal goals and health.