Period & Health

Written by: Katrine Svensmark

From Follicles to Fertility: Navigating the Maze of Uterus Follicle Age, Egg Quality, and Fertility Potential

Fertility is a complex process influenced by factors such as follicles, eggs, and the age of the uterus. Understanding the interplay between these components is crucial for individuals on their reproductive journey. In this article, we explore the role of follicles in producing eggs, the impact of age on egg quantity and quality, the age-related changes in the uterus that affect fertility, and what is a good size follicle for fertilization. By delving into these intricate connections, we aim to provide valuable insights into reproductive health, fertility potential and informed decision-making regarding evaluation and treatment options. Let us embark on a journey into the intriguing realm of human reproduction and explore the intricate nuances that shape our path toward parenthood.

Fertility: Factors and Aging in Reproductive Health

Fertility, the ability to conceive and carry a pregnancy to term, is a complex process influenced by various factors. It involves the harmonious interaction between follicles, eggs, and the uterus. While follicles produce eggs and the uterus provides the environment for implantation and pregnancy, fertility encompasses more than just these components. It also considers factors such as hormone levels, sperm quality, fallopian tube health, and overall reproductive health. Achieving and maintaining fertility involves the coordination of numerous intricate processes within the female reproductive system. Age is also a significant factor that impacts fertility, as the quantity and quality of eggs decline over time, and the uterus undergoes age-related changes. Understanding the multifaceted nature of fertility and seeking appropriate evaluation and treatment options when necessary can help individuals navigate their reproductive journey.

Fun fact:

Were you aware that the most extended documented pregnancy in history lasted an incredible 375 days? In 1945, a woman named Beulah Hunter from the United States held the record for the longest gestation period. She carried her baby for over a year before finally giving birth. While the average pregnancy duration is around 40 weeks or 280 days, Beulah Hunter’s case demonstrates the exceptional and rare circumstances that can occur in the realm of human reproduction. Her extraordinary experience serves as a reminder that each pregnancy is unique and can deviate from the norm in surprising ways.

Follicles: Key Players in Reproduction and Fertility

Follicles are tiny, fluid-filled structures found in a woman’s ovaries that play a vital role in reproduction. Each follicle contains an immature egg surrounded by specialized cells. These cells nourish and support the developing egg. The journey of follicles begins during fetal development when millions of primordial follicles, which are the earliest stage of follicle development, form in the ovaries. These follicles remain dormant until a woman reaches puberty. During her reproductive years, a complex hormonal process stimulates a group of follicles to grow and develop during each menstrual cycle. Typically, only one follicle becomes dominant, reaching full maturity for ovulation. The dominant follicle grows and forms a fluid-filled cavity called the antrum, housing the mature egg. When the dominant follicle reaches its peak size, it releases a surge of luteinizing hormone (LH), triggering ovulation. The mature egg is then released into the fallopian tube, ready for fertilization. The remaining follicles that do not reach maturity undergo a process called atresia, where they degenerate and are absorbed by the body. This cyclical follicular development and selection process represents a woman’s ovarian reserve, which refers to the quantity and quality of remaining follicles. As a woman ages, her ovarian reserve naturally declines, leading to decreased fertility. Monitoring follicle development and assessing ovarian reserve through techniques like ultrasound imaging and hormone level measurements can provide valuable insights into a woman’s reproductive health and fertility potential.

Eggs: Quantity, Quality, and Impact on Female Fertility

What is a good size follicle for fertilization?

Eggs, or oocytes, are crucial female reproductive cells for fertilization and reproduction. In a female fetus at around 20 weeks of gestation, there are about six to seven million eggs. However, this number decreases to approximately one to two million at birth. As a woman ages, the number of eggs gradually declines. Puberty marks the stage when she may have around 300,000 to 500,000 eggs left. Over her reproductive years, this count naturally decreases. By age 35, it is estimated that around 25,000 eggs remain. As menopause approaches (usually in the late 40s or early 50s), the ovarian reserve further diminishes, leaving only a few thousand eggs. It’s important to remember that these numbers are approximations and can vary among individuals.

Alongside the decrease in quantity, the quality of eggs also declines with age. As women age, their eggs may be more prone to chromosomal abnormalities, such as those causing down-syndrome or other genetic conditions. This decline in egg quality can lead to a decrease in fertility and an increased risk of miscarriages. It’s important to understand that not all eggs are able to become fertilized or develop into healthy embryos, particularly as women reach their late 30s and beyond. This highlights the significance of monitoring ovarian reserve and egg quality, especially for women considering fertility treatments or those concerned about their fertility potential as they age.

The Uterine Age: Implications for Reproductive Health and Pregnancy

The age of the uterus, also known as the uterine age, refers to the condition and functionality of the uterus in relation to a woman’s reproductive health. While the focus is often placed on the age and quality of eggs and follicles, the age of the uterus also plays a role in fertility. The uterus undergoes changes throughout a woman’s life, particularly in response to hormonal fluctuations during the menstrual cycle. The lining of the uterus, known as the endometrium, thickens and sheds during each cycle to facilitate potential embryo implantation. As a woman ages, the uterus may experience natural changes, including a reduction in its ability to support pregnancy and maintain a healthy environment for embryo development. These age-related changes can contribute to difficulties in achieving and sustaining pregnancy. Understanding the age-related changes in the uterus is vital for individuals seeking to conceive, as it can provide valuable insights into their reproductive potential and guide fertility evaluation and treatment decisions.


In conclusion, fertility is a complex process involving the interaction of follicles, eggs, and the uterus. Understanding the role of each component is crucial for individuals navigating their reproductive journey. Monitoring follicle development and assessing ovarian reserve provide insights into reproductive health. The diminishing quantity and quality of eggs with age underscore the importance of fertility awareness. The age-related changes in the uterus also impact fertility outcomes. Individuals can make informed decisions and seek port by recognizing these factors. Each fertility journey is unique, and with advancements in reproductive technologies, the possibilities of parenthood continue to expand, offering hope to those pursuing their dreams of starting a family.


  • Cleveland Clinic. (2019, January 19). Female Reproductive System. Cleveland Clinic; Cleveland Clinic. Retrieved the 10. July, from Link

  • Eunice Kennedy Shriver National Institute of Child Health and Human Development – NICHD. (n.d.). Retrieved the 10. July, from Link

  • Fortune, J. E. (1994). Ovarian Follicular Growth and Development in Mammals1. Biology of Reproduction, 50(2), 225–232. Retrieved the 10. July, from Link

  • Gossman, W., Fagan, S. E., Sosa-Stanley, J. N., & Peterson, D. C. (2019, July 11). Anatomy, Abdomen and Pelvis, Uterus.; StatPearls Publishing. Retrieved the 10. July, from Link

  • How many eggs does a woman have? At birth, 30s, and menopause. (2022, April 6). Retrieved the 10. July, from Link

  • Moghadam, A. R. E., Moghadam, M. T., Hemadi, M., & Saki, G. (2021). Oocyte quality and aging. JBRA Assisted Reproduction. Retrieved the 10. July, from Link

  • Nelson, S. M., Telfer, E. E., & Anderson, R. A. (2012). The ageing ovary and uterus: new biological insights. Human Reproduction Update, 19(1), 67–83. Retrieved the 10. July, from Link

  • Owen, A., & Sparzak, P. B. (2022). Age Related Fertility Decline. PubMed; StatPearls Publishing. Retrieved the 10. July, from Link

  • Palma, G. A., Argañaraz, M. E., Barrera, A. D., Rodler, D., Mutto, A. Á., & Sinowatz, F. (2012). Biology and Biotechnology of Follicle Development. The Scientific World Journal, 2012, 938138. Retrieved the 10. July, from Link

  • Richards, J. S., & Pangas, S. A. (2010). The ovary: basic biology and clinical implications. Journal of Clinical Investigation, 120(4), 963–972. Retrieved the 10. July, from Link

  • Sharma, R., Biedenharn, K. R., Fedor, J. M., & Agarwal, A. (2013). Lifestyle factors and reproductive health: taking control of your fertility. Reproductive Biology and Endocrinology, 11(1), 66. Retrieved the 10. July, from Link

  • The Woman Who Was Pregnant for 12 Months – History of Yesterday. (2022, September 2). Retrieved the 10. July, from Link

  • VARTA. (n.d.). Fertility explained | VARTA. Retrieved the 10. July, from Link

Leave a Reply