Ovulation and menstruation at the same time: is this possible?

By BSc (biologist & science teacher), (gynecologist), (embryologist) and (invitra staff).
Last Update: 04/28/2020

Normally, a woman's menstrual cycle lasts about 28 days. Ovulation usually occurs towards the middle of this cycle, that is, about 14 days after the beginning of menstruation.

However, this is not always the case. For example, in a short menstrual cycle (less than 25 days) the time of ovulation and menstruation can be very close together and lead to confusion.

It is also possible to confuse metrorrhagia with a regular period. An intermenstrual bleeding occurs when blood spots appear between one period and the next. Thus, there is a possibility that this accelerated onset of the period coincides with the time of ovulation.

If a woman thinks she is in her menstrual phase, i.e. on less fertile days, when she is actually at the time of ovulation, the chances of pregnancy increase.

When does menstruation take place?

Menstruation, also called a period, is typical bleeding that is a mixture of vaginal fluid, blood, and endometrial tissue. This phase of the cycle usually lasts between 3 and 5 days, although it depends on each woman.

Menstruation occurs in the first phase of the menstrual cycle when there is a drop in estrogen and progesterone in a woman's body. This decrease causes the shedding of the endometrium, the layer that covers the inside of the uterus.

Women have regular menstruation and menstrual cycles until they reach menopausal age, which is usually around 50.

If you want more information about this phase of a woman's cycle, you can click here: Menstruation: symptoms and characteristics of the monthly bleeding.

When does ovulation happen?

Generally, a woman's menstrual cycle is 28 days long and ovulation occurs on day 14 or 15 of the cycle which is triggered by a spike in LH hormone.

The mature egg leaves the ovary and reaches the Fallopian tubes, where it remains for 12-24 hours. If fertilization with sperm does not take place during this time, the egg will age and dissolve.

However, women can also present:

  • Short menstrual cycles: less than 25 days, so ovulation will occur around day 11 or 12 of the cycle.
  • Long menstrual cycles: more than 28 days, so ovulation usually moves backwards. For example, if the cycle lasts 36 days, ovulation takes place between day 19 and day 23.

Ovulation indicates the most fertile moments of a woman, which means when conception would take place when having unprotected intercourse.

Calculating the moment of ovulation

Traditional methods of menstrual cycle control (fertile days) are not always effective since ovulation may advance or postpone en each cycle. To calculate the date of ovulation it is necessary to take into account the length of each woman's cycle, external variations, the number of ovulation per cycle, etc.

As we have already mentioned, ovulation occurs on day 14 of the cycle, considering the beginning of the cycle on the first day of menstruation. However, some women ovulate earlier or later. Therefore, we cannot talk about a general system of calculating a woman's most fertile time.

Ovulation tests would be another method for calculating the date of ovulation. These tests are based on measuring levels of LH in the urine, a hormone that increases exponentially 24-36 hours before ovulation.

Keep in mind that for women who ovulate several times in a month, ovulation may temporarily coincide with menstruation and cause an alteration in the fertility calendar.

Differences between ovulation and menstruation

Throughout a woman's menstrual cycle, ovarian follicles grow and develop, but only one will reach the final stage of maturation. This follicle manages to break down and release a mature egg at the time of ovulation. The egg falls into the Fallopian tube and will remain alive for up to 24 hours waiting to be fertilized.

If after 24 hours no sperm can reach the Fallopian tubes to fertilize the egg, the egg ages and is lost during menstruation.

Therefore, we are talking about two paths that occur in different places:

  • Uterus: the endometrium grows throughout a woman's entire menstrual cycle while waiting for an embryo to implant in it. If this implantation does not take place, the endometrium is shed in the form of bleeding, which is what we call menstruation. When menstruation ends, this uterine layer will re-grow and renew itself.
  • Ovary: is the place where follicles develop. One of them, that is, the dominant follicle that reaches the final stage of maturation, will release an egg (ovulation) that can be fertilized or discarded. If the egg is fertilized by the sperm, the follicle begins to degenerate and is called corpus luteum. If, on the other hand, there is no fertilization, the corpus luteum stops releasing hormones, causing the endometrium to be shed in the form of menstruation.

Can menstruation and ovulation occur at the same time?

For women with menstrual cycles shorter than 25 days, ovulation and periods may coincide. Although this situation is not very common, it is possible.

If intercourse were held during menstruation, since sperm can live for 2 to 5 days in the female reproductive tract, an egg that has been expelled a few days later could be fertilized. Therefore, sperm remain alive at the beginning of ovulation in women with short menstrual cycles.

In short or irregular menstrual cycles there may be a coincidence between the date of ovulation and the date of menstruation.

FAQs from users

Is it possible to ovulate while still bleeding from menstruation?

By Dra. Jessica García Cataño (gynecologist).

For women who have regular and normally long menstrual cycles, it would be unlikely that ovulation would occur during menstrual bleeding. However, this may happen on occasion.
Read more

Is it true that I can't get pregnant during my period?

By Marta Barranquero Gómez (embryologist).

No. It is a mistake to think that if you have unprotected sex during menstruation, it is impossible to get pregnant. Although this is unlikely to happen, it is absolutely possible.

Most women have normal menstrual cycles, which are 28 to 32 days long. In these cases, pregnancy is rare during the period.

However, some women have short menstrual cycles (less than 25 days) and ovulation and menstruation may coincide. These women can get pregnant by having unprotected sex during the menstrual phase.

Is there always menstruation when there is ovulation?

By Marta Barranquero Gómez (embryologist).

No. It is a mistake to think that if you have unprotected sex during menstruation, it is impossible to get pregnant. Although this is unlikely to happen, it is absolutely possible.

Most women have normal menstrual cycles, which are 28 to 32 days long. In these cases, pregnancy is rare during the period.

However, some women have short menstrual cycles (less than 25 days) and ovulation and menstruation may coincide. These women can get pregnant by having unprotected sex during the menstrual phase.

Is it possible for two ovulation to occur in the same woman's menstrual cycle?

By Marta Barranquero Gómez (embryologist).

Yes, it's possible. Also, this fact would explain the origin of the non-identical twins. In these situations, the fertilization of two different eggs by two sperm occurs, which is known as super-fertilization.

Do you ovulate from one ovary every month?

By Marta Barranquero Gómez (embryologist).

No. The ovulation process occurs randomly in the ovaries. It does not follow a specific pattern.

There are many follicles in the ovary and only one of them will reach the final stage of maturation. This follicle is called the dominant follicle and it will generate some substances that block the development of the others. All this happens in the ovarian tissue, regardless of whether it is in the right or left ovary.

Suggested for you

For more information on menstrual cycle functioning, read on in the following article: The Menstrual Cycle: What Happens in Each of Its Phases?

Also, we have commented that when the woman reaches menopausal age, menstruation completely stops. If you want to read more about it, you can click here: When does menopause begin?

Our editors have made great efforts to create this content for you. By sharing this post, you are helping us to keep ourselves motivated to work even harder.

References

Authors and contributors

 Iván Ferrer Durbà
Iván Ferrer Durbà
BSc
Biologist & Science Teacher
Bachelor's Degree in Biology by the University of Valencia (UV). Postgraduate Course in Secondary Education and Teaching by the University of Portsmouth. Teacher of Sciences at multiple British schools and high schools. More information about Iván Ferrer Durbà
Dra. Jessica García Cataño
Dra. Jessica García Cataño
Gynecologist
Degree in Medicine from the University of Guadalajara in Mexico, specializing in Gynecology and Obstetrics at the Fray Antonio Alcalde Civil Hospital. After completing a Master's in Human Reproduction at the Complutense University of Madrid, she became part of the Clinica Tambre gynecology team. More information about Dra. Jessica García Cataño
 Marta Barranquero Gómez
Marta Barranquero Gómez
Embryologist
Graduated in Biochemistry and Biomedical Sciences by the University of Valencia (UV) and specialized in Assisted Reproduction by the University of Alcalá de Henares (UAH) in collaboration with Ginefiv and in Clinical Genetics by the University of Alcalá de Henares (UAH). More information about Marta Barranquero Gómez
License: 3316-CV
Adapted into english by:
 Romina Packan
Romina Packan
inviTRA Staff
Editor and translator for the English and German edition of inviTRA. More information about Romina Packan

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