Beyond Egg Quality: How Age May Affect Uterine Receptivity

Advanced Maternal Age and Uterine Receptivity: A Relationship Egg Quality Alone Cannot Explain

To the women in their twenties and thirties who carry a vague unease about future pregnancy and childbirth, and to their partners: when you begin reading about fertility treatment or trying to conceive, you probably encounter the phrase "declining egg quality" again and again. It is true, and well established, that egg quality changes as a woman grows older. Yet recent research suggests that in pregnancy at an older age, the difficulty conceiving may not be explained by egg quality alone, and that the receptivity of the uterus itself may also be deeply involved. Whatever feelings and worries you are holding right now, they are not wrong.

As a fertility specialist, what I want to do in this article is explain, on the basis of objective information, how advanced maternal age may influence uterine receptivity, and how that in turn may contribute to implantation failure. I hope it helps you build a calm and accurate understanding of a genuinely complex subject.

What Is Uterine Receptivity?

Uterine receptivity refers to the state in which a fertilized egg can successfully implant in the endometrium and the pregnancy can continue. After ovulation, hormones remodel the endometrium into a state suited to implantation. This period is called the implantation window, and it is a very limited span of time. When uterine receptivity is reduced, implantation can become difficult even when a good-quality embryo is available, which may lead to implantation failure or early pregnancy loss.

How Advanced Maternal Age May Affect Uterine Receptivity

The fall in pregnancy rates with advanced maternal age has generally been attributed mainly to a rise in chromosomal abnormalities in the egg — that is, to declining egg quality. In recent years attention has also turned to factors on the uterine side.

It is worth being clear about where this field actually stands.

A 2023 review (PMID: 37468438) sets out how ageing produces molecular, cellular and histological changes in the endometrium that may impair receptivity. But the same review states two things explicitly:

There are only a few published studies on this topic, and the area is under-explored
★In oocyte donation cycles — the design that isolates the uterine contribution — the studies of implantation, clinical pregnancy, miscarriage and live birth rates have produced contradictory inferences

The second point is the important one. With donor oocytes, egg quality is held at a young donor's level, so what remains is the uterine side. That the results in this design contradict each other means it is not settled that uterine receptivity is a cause of age-related infertility.

So what follows below are proposed mechanisms, not established causes. Please read them that way.

It should also be said that this is a narrative review rather than a meta-analysis, and its title — "an underrated factor" — signals the position its authors are arguing.

Specifically, the following mechanisms have been proposed.

1. Changes in the Endometrium

With advancing age, changes at the cellular level may occur within the endometrium. For example, it has been suggested that the proliferative capacity of endometrial cells, and the expression patterns of certain genes needed for implantation, may change. As a result, the environment that allows a fertilized egg to attach to the endometrium may no longer be optimal. Changes in inflammatory responses and immune responses within the endometrium are also being studied as factors that may affect implantation.

2. Changes in the Hormonal Environment

As a woman ages, ovarian function declines, and the secretion patterns of hormones across the menstrual cycle, including estrogen and progesterone, may change. These hormones are essential for preparing the endometrium, and an imbalance between them may reduce uterine receptivity. Attempts are being made to address this with hormone supplementation, but careful consideration of each individual situation is required.

3. Other Uterine Factors

The incidence of uterine conditions such as fibroids and endometrial polyps also tends to rise with age. These may physically or physiologically interfere with normal endometrial function and with implantation of the embryo. Detecting such abnormalities early through regular gynecologic check-ups, and treating them appropriately, is important.

Implantation Failure and Advanced Maternal Age

Implantation failure describes a situation in which pregnancy does not occur despite repeated transfers of good-quality embryos. In women conceiving at an older age, both the decline in egg quality described above and reduced uterine receptivity may be involved together, raising the risk of implantation failure. Understanding this complex relationship, and approaching it from both the egg side and the uterine side, is essential to building an effective treatment strategy.

What You Can Do

As with egg quality, much about uterine receptivity at an older age remains unexplained, and no specific intervention has been firmly established. What is clear is that general health maintenance and preconception care, which help bring the body into good condition, matter for everyone at any age. A balanced diet, moderate exercise, stress management, not smoking and limiting alcohol may all have a favorable influence not only on overall health but also on reproductive function.

It also helps to have regular gynecologic check-ups so that you know the state of your uterus and ovaries. If you are thinking about trying to conceive, consulting a specialist early, and obtaining accurate information and support tailored to your own situation, can be valuable for your peace of mind as well. I encourage you to value your own feelings as you move toward the choices you can be at peace with. When you feel anxious, please do not carry it alone. Talk with someone you trust, or with a professional.

Frequently Asked Questions (FAQ)

Q1: Can a test tell me whether my uterine receptivity is reduced because of my age?

A1: At present there is no established test that directly and accurately measures uterine receptivity. Tests that attempt to assess the implantation window, such as the ERA test, do exist, but their usefulness is still debated. Usually we evaluate endometrial thickness and appearance by ultrasound, and check for abnormalities inside the uterine cavity by hysteroscopy. A more detailed assessment requires a comprehensive judgment that takes in your medical history and the course of your fertility treatment.

Q2: Are there specific ways to improve uterine receptivity?

A2: There is as yet no specific established treatment that dramatically improves uterine receptivity in pregnancy at an older age. However, depending on the state of the individual endometrium, we may adjust hormone supplementation, or treat inflammation in the endometrium, for example with antibiotics for chronic endometritis. Where fibroids or polyps are present, surgical removal may also be considered. Keeping general health in good shape is thought to support uterine health as well.

Q3: Which matters more, egg quality or uterine receptivity?

A3: For the decline in pregnancy rates with age, the stronger evidence is on the egg quality side. For uterine receptivity, the studies in oocyte donation cycles that could isolate it have produced contradictory results (PMID: 37468438), so how much it contributes is unsettled. Both are necessary for a pregnancy, but there is not enough data to say they are equally responsible. Talking with a specialist and building a treatment plan that fits your situation is what counts.

Summary

For the decline in pregnancy rates with age, the stronger evidence is on the egg quality side. The hypothesis that uterine receptivity also contributes is real, and molecular and cellular changes have been reported — but ★in oocyte donation cycles, the design that isolates it, the results contradict each other (PMID: 37468438), and the degree of contribution is unsettled. This is an area the review's own authors describe as under-explored.

For now there are no established treatments that directly improve uterine receptivity. Even so, the effort to keep the uterus healthy through preconception care and regular gynecologic check-ups is worthwhile. Face your own body kindly, gather sound information, and move forward with your fertility journey with as much reassurance as possible.

References

Endometrial receptivity in women of advanced age: an underrated factor in infertility. Hum Reprod Update. 2023. PMID: 37468438 (a narrative review; the authors state that the area is under-explored and that the oocyte donation studies have produced contradictory inferences)