How Long Does Ovulation Last?

When you’re trying to get pregnant, you are likely looking to figure out when you are fertile, and know that your fertile window depends on when you are ovulating. 

What is ovulation and when does it occur?

Ovulation is when an egg is released from one of your ovaries and stays in the fallopian tube for 12-24 hours waiting to be fertilized.

It is not a spontaneous occurrence – your body has been preparing for this stage for 2 weeks. Menses (the time you are bleeding) starts from day 1 and usually last for about 5 days. During this period, the lining of the uterus sheds out through the vagina if pregnancy has not occurred. Between days 6 and 14, follicles in one of your ovaries undergo its maturation process, and only one follicle will develop into a mature egg, also known as ovum. Following a surge of luteinizing hormone (LH), the egg is released, triggering ovulation which typically occurs between day 14 and 16 of an average menstrual cycle[1]

How long does ovulation last?

While the fertile window spans about 6 days, ovulation only lasts about 24 hours. Sperm can survive in the female body for up to 5 days. If fertilization doesn’t occur,  the egg itself will dissolve within 12-24 hours[2].

Ovulation in irregular cycles

Absent or irregular periods are usually an indication of irregular or absent ovulation. Generally, you can be considered to have irregular periods if your menstrual cycle is shorter than 21 days, longer than 35 days[3], or if it varies more than 20 days from month to month[4]. If your period is completely absent during your reproductive years, you may have a condition known as amenorrhea[5] .  A majority of women with amenorrhea don’t ovulate, which is also known as anovulation. 1 in 10 people with ovaries experience anovulation, which is when the ovaries do not release an egg during the menstrual cycle, at some point during their childbearing years[6]

When a person is anovulatory, they cannot get pregnant because there is no egg to be fertilized. However, if you are ovulating but have an irregular cycle, you can still conceive by utilising methods to calculate your fertility window. In either case, you may want to consult your doctor to address the root cause of your irregular or absent periods.

Remember that it’s important to understand and listen to your body. If you want more information regarding your fertility questions or concerns, start by checking your fertility status.

If you’re in Malaysia or Singapore, you have easier access to some of the top fertility specialists and fertility clinics around. We advocate finding a fertility specialist you feel comfortable with. For a list of questions to ask, check out this list of questions. 


[1] Soumpasis, I., Grace, B., & Johnson, S. (2020). Real-life insights on menstrual cycles and ovulation using big data. Human Reproduction Open, 2020(2).

[2]  Higuera, V. (2018, December 7). How Long Does Ovulation Last Each Month? Healthline.

[3] Pregnancy tests | Office on Women’s Health. (n.d.). Office on Women’s Health.

[4] Munro, M. G., Critchley, H. O., & Fraser, I. S. (2012). The FIGO systems for nomenclature and classification of causes of abnormal uterine bleeding in the reproductive years: Who needs them? American Journal of Obstetrics and Gynecology. doi: 10.1016/j.ajog.2012.01.046

[5] Rebar R. Evaluation of Amenorrhea, Anovulation, and Abnormal Bleeding. [Updated 2018 Jan 15]. In: Feingold KR, Anawalt B, Boyce A, et al., editors. Endotext [Internet]. South Dartmouth (MA):, Inc.; 2000-. Available from:

[6] Anovulation: Signs, Symptoms, Causes & Treatment. (n.d.). Cleveland Clinic.


MY-NONF-00198 | 13 July 2023

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