When people talk about age and fertility, most of the attention goes to eggs. As we get older, egg quality declines, which can make conception more difficult and increase the risk of miscarriage.

However, researchers are also studying another piece of the puzzle: how the uterus itself may change over time. This process is referred to as uterine aging.

While egg health remains the most important age-related fertility factor, understanding uterine changes can help explain why fertility is complex — and why a supportive uterine environment matters too.

What Is Uterine Aging and How Does It Affect Fertility?

Uterine aging refers to gradual, natural changes that can occur in the:

• Muscles of the uterus
• Blood vessels that supply it
• Inner lining of the uterus (the endometrium)

These changes may affect:

• How the lining responds during embryo implantation
• How the uterus supports a growing pregnancy
• How the uterus functions later in pregnancy and labor

Some studies suggest that, with age, the uterine lining may become less responsive to hormones, slightly thinner, or more prone to inflammation. These shifts do not mean pregnancy cannot happen — but they may influence how easily implantation occurs or how supportive the environment is early in pregnancy.

Egg Quality vs. Uterine Health: What Matters Most With Age

Egg quality is still the primary driver of age-related fertility decline. Changes in egg chromosomes are well documented and explain most of the reduced pregnancy success rates seen as women get older.

However, researchers have noticed something interesting:
Pregnancy rates may sometimes be lower in older women, even when using healthy donor eggs. This suggests that the uterus may also contribute in some cases.

Studies looking at uterine aging have had mixed results. Some show that the uterine lining becomes less effective at supporting implantation over time, while other studies have found little difference once embryo quality is carefully controlled.

This ongoing research highlights an important point: fertility is influenced by multiple systems working together, not just one factor alone.

Age-Related Uterine Conditions That Can Affect Pregnancy

As we age, we are also more likely to develop medical or gynecologic conditions that can affect fertility or pregnancy, including:

• Fibroids
• Adenomyosis
• Endometriosis
• Polyps
• Uterine scar tissue from prior surgeries
• Diabetes or insulin resistance
• Thyroid disorders
• High blood pressure or cardiovascular disease
• Autoimmune conditions

These factors can affect implantation, pregnancy progression, or overall health during pregnancy.

Pregnancy Risks at Advanced Maternal Age

Pregnancy later in life — especially after age 45 — is associated with higher risks, including:

• Gestational diabetes
• High blood pressure and preeclampsia
• Placental complications
• Fetal complications
• Preterm birth
• Cesarean delivery

Babies born to older parents may also be more likely to need specialized care after delivery, such as monitoring in a neonatal intensive care unit (NICU).

These risks do not mean pregnancy is not possible later in life. They simply mean closer monitoring and individualized care become more important.

Can Uterine Aging Be Treated or Improved?

Researchers are exploring potential approaches to support uterine health, including treatments aimed at reducing inflammation or oxidative stress, and even regenerative therapies such as stem cells.

Right now, these options are still experimental and not part of routine fertility treatment.

The most effective steps today focus on overall health and medical optimization, such as:

• Managing chronic health conditions
• Treating uterine conditions like fibroids or polyps
• Ensuring proper hormonal support
• Working closely with a fertility specialist when needed

Key Takeaway: Understanding Uterine Aging in Your Fertility Journey

Egg quality remains the most important factor in age-related fertility decline. However, the uterus may also change over time in ways that influence implantation and pregnancy.

Understanding uterine aging adds clarity to the family building journey. By addressing both egg and uterine health, and working closely with your care team, you can make informed decisions and create the best possible conditions for a healthy pregnancy.

This information has been medically reviewed by Tendai M. Chiware, M.D. the Director of the Third Party Reproduction Program at Genesis Fertility