The Clock is Ticking: Demystifying Diminished Ovarian Reserve (DOR) and Its Impact on Fertility

As you embark on your journey to conceive, you may find yourself worried about your ovarian reserve and egg quality. Age is the most significant and prevalent factor influencing ovarian reserve, which refers to the number and quality of eggs a woman has. As a woman ages, her egg reserves naturally diminish. 

It is estimated that women lose approximately 1,000 eggs per menstrual cycle, and this gradual decline in egg quantity typically starts to impact fertility after the age of 35[1]. Similarly, egg quality also tends to decline with age. After the age of 35, the quality of eggs may decrease by up to 10% each year[2].

Let’s delve deeper and discover more about the Diminished Ovarian Reserve condition.

What is Diminished Ovarian Reserve?

DOR or also known as Diminished Ovarian Reserve, refers to a condition in which a woman’s ovaries have a lower quantity and/or quality of eggs than expected for her age[3]. It is a term used to describe a decline in ovarian function, resulting in a reduced number of viable eggs available for conception.

DOR can occur at any age but is more commonly seen in women who are in their late 30s or older. However, it can also affect younger women. Some common causes of DOR include age-related factors, genetic conditions, previous surgeries, exposure to certain chemotherapy or radiation treatments, and certain autoimmune conditions.

DOR is often clinically asymptomatic and a woman with this condition may experience any of the following[4]:

  • Late or absent menstrual periods
  • Shorter menstrual cycles than average, with the average being 28 days
  • Heavy menstrual flow

Risk Factors

You may also be at risk of having DOR, especially if you have previously experienced any of the following:


  • A tubal disease or pelvic infection[5]
  • Endometriosis[6]
  • Polycystic Ovarian Syndrome (PCOS)[7]
  • Prior ovarian surgery[8]
  • Chemotherapy or radiation therapy[9]
  • History of smoking or using illicit drugs[10]
  • Autoimmune disorders[11]
  • A poor diet or higher BMI than recommended[12] 


If you have any of the symptoms or risk factors mentioned above or if you’ve been experiencing difficulty conceiving, it may be wise to seek a proper diagnosis. Several tests can be performed to ascertain if DOR is present. Some of these tests include:


  • Follicle Stimulating Hormone (FSH) Test


This routine test measures the level of FSH in the female body, usually right before the estimated time of ovulation. FSH is produced by the pituitary gland in the brain and supports ovulation by driving the growth of follicles in the ovaries, which in turn produce other hormones like AMH, estrogen and progesterone. Low levels of FSH can signal an irregular cycle, while high levels of FSH can signal DOR[13].


  • Anti-Mullerian Hormone (AMH) Test


The AMH test measures the level of the Anti-Mullerian hormone, which is a hormone produced by cells inside the follicles of the ovaries[14]. This test is a sensitive indicator that signals ovarian aging and has age-specific ranges, making it the most reliable test for DOR currently available, compared to the FSH test. This is because AMH levels can decline well before FSH levels rise, thus allowing for an early diagnosis[15]. Ideally, the AMH level should be in the normal range for your age group.


  • Antral Follicle Count


Alongside hormone tests, your medical practitioner may also conduct an antral follicle count which allows them to count the follicles visible during a transvaginal ultrasound[16]. The follicles that are visible are antral stage follicles, which are at the late stage of egg maturation. Ideally, the number of antral follicles should be within the normal range. Too many follicles can indicate Polycystic Ovarian Syndrome (PCOS) and too few may indicate Premature Ovarian Failure[17].


Over the last five decades, Malaysia has witnessed a consistent decline in the Total Fertility Rate (TFR) among women of reproductive age. If this declining trend continues, experts predict that the country’s population growth rate is expected to reach a mere 0.7 per cent by the year 2050[18]. Similarly, Singapore has also experienced a significant decline in its birth rate, hitting a record low in 2022 with only 35,605 babies born in that year[19].


While declining birth rates in both countries may reflect societal changes and advancements in family planning, it also brings attention to the issue of Delayed-Onset of Reproduction (DOR), a phenomenon where individuals delay having children until later in life. DOR can be challenging to navigate emotionally, seeking professional support and staying informed about available fertility treatments can empower you to make the best decisions for your family planning goals.


Both Malaysia and Singapore, as progressive nations, have been proactive in promoting family planning services and providing resources to address fertility issues, acknowledging the importance of supporting individuals and couples in their journey towards parenthood.


If you need further information or have other concerns, read this article for the 10 things you should do when trying to conceive, or try starting with our fertility questionnaire.


[1]  Ding, J., & Pundir, J. (2018). Poor Oocyte Quality—Ovarian Aging. Recurrent Pregnancy Loss, 16. 

; Female Age-Related Fertility Decline. (n.d.). ACOG.

[2] Silber, S. J., Kato, K., Aoyama, N., Yabuuchi, A., Skaletsky, H., Fan, Y., … & Kobayashi, T. (2017). Intrinsic fertility of human oocytes. Fertility and Sterility, 107(5), 1232-1237.

[3] Jirge P. R. (2016). Poor ovarian reserve. Journal of human reproductive sciences, 9(2), 63–69.

[4] Ferguson, S. (2019, February 26). What Is Diminished Ovarian Reserve and What Can You Do About It? Healthline.

[5] Cui L, Sheng Y, Sun M, Hu J, Qin Y, Chen ZJ. Chronic Pelvic Inflammation Diminished Ovarian Reserve as Indicated by Serum Anti Mülerrian Hormone. PLoS One. 2016 Jun 6;11(6):e0156130. doi: 10.1371/journal.pone.0156130. PMID: 27272680; PMCID: PMC4894572.

[6] Xu, B., Guo, N., Zhang, X. M., Shi, W., Tong, X. H., Iqbal, F., & Liu, Y. S. (2015). Oocyte quality is decreased in women with minimal or mild endometriosis. Scientific Reports, 5(1), 1-8.

[7] Gong, Y., Luo, S., Fan, P., Jin, S., Zhu, H., Deng, T., … & Huang, W. (2020). Growth hormone alleviates oxidative stress and improves oocyte quality in Chinese women with polycystic ovary syndrome: a randomized controlled trial. Scientific reports, 10(1), 1-10.

[8] Ferguson, S. (2019, February 26). What Is Diminished Ovarian Reserve and What Can You Do About It? Healthline.

[9] Kim, S., Kim, S. W., Han, S. J., Lee, S., Park, H. T., Song, J. Y., & Kim, T. (2021). Molecular mechanism and prevention strategy of chemotherapy-and radiotherapy-induced ovarian damage. International Journal of Molecular Sciences, 22(14), 7484.

[10] van Ravesteijn, H. J., Lucassen, P. L., & olde Hartman, T. C. (2008). Reattribution for medically unexplained symptoms. The British Journal of Psychiatry, 192(4), 314-315.

[11] Miller, J. E., Ahn, S. H., Monsanto, S. P., Khalaj, K., Koti, M., & Tayade, C. (2017). Implications of immune dysfunction on endometriosis associated infertility. Oncotarget, 8(4), 7138

[12] Robker, R. L., & Norman, R. J. (2013). Obesity and oocyte quality. Biology and Pathology of the Oocyte: Role in Fertility, Medicine and Nuclear Reprograming, 2, 362-370.; Bishop, C. V., Reiter, T. E., Erikson, D. W., Hanna, C. B., Daughtry, B. L., Chavez, S. L., … & Stouffer, R. L. (2019). Chronically elevated androgen and/or consumption of a Western-style diet impairs oocyte quality and granulosa cell function in the nonhuman primate periovulatory follicle. Journal of assisted reproduction and genetics, 36(7), 1497-1511.

[13]  MacMillan, C. (2018, August 2). Women, How Good Are Your Eggs? Yale Medicine.

[14] Anti-Mullerian Hormone (AMH) Test: Purpose, Levels & Results. (n.d.). Cleveland Clinic.,of%20AMH%20for%20their%20development.

[15] Toner, J. P., & Seifer, D. B. (2013). Why we may abandon basal follicle-stimulating hormone testing: a sea change in determining ovarian reserve using antimüllerian hormone. Fertility and sterility, 99(7), 1825-1830.

[16] Scheffer, G. J., Broekmans, F. J., Dorland, M., Habbema, J. D., Looman, C. W., & te Velde, E. R. (1999). Antral follicle counts by transvaginal ultrasonography are related to age in women with proven natural fertility. Fertility and sterility, 72(5), 845-851.

[17] Beck-Peccoz, P., & Persani, L. (2006). Premature ovarian failure. Orphanet Journal of Rare Diseases, 1(1).



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