Yes. Contrary to popular belief, it is possible for a woman to get pregnant if she has sexual intercourse during her period. While a woman’s chances of becoming pregnant are greatest during the fertile days of her menstrual cycle, women with shorter cycles may be able to conceive on the last day or so of their periods.

A woman’s menstrual cycle usually lasts about 28 days, and it follows these four phases: menstruation, the follicular phase, ovulation, and the luteal phase. During menstruation, the lining of a woman’s uterus that has built up over the course of about a month breaks down and exits the body through the cervix and out of the vagina. This is more commonly known as a “period,” and it generally lasts between 5-7 days.

The pituitary gland in the brain releases a hormone to produce follicles on an ovary during the follicular phase of the menstrual cycle around day 10. Ordinarily, just one of these follicles matures into an egg. The lining of the uterus begins to build up again during the follicular phase.

A woman is most fertile during ovulation, when one of the ovaries releases an egg. The egg then travels down the adjacent fallopian tube where it is available to be fertilized by a sperm. Fertilization occurs in one of the fallopian tubes. Typically, ovulation occurs around day 14 of the menstrual cycle. The ovulation process itself only lasts 12 to 24 hours, but women are most likely to get pregnant in the days immediately before or after ovulation.

Lastly, during the luteal phase, the egg journeys to the uterus. If the egg has not been fertilized by a sperm, the luteal phase will end when a woman gets her period again. This phase generally lasts from 12 to 14 days.

Although it is true that a woman may be less likely to become pregnant while on her period, there are a few ways in which it can occur. First, not all women have the same menstrual cycle length. While the average menstrual cycle lasts 28 days, women may have cycles that range from 21 to 35 days in length. As such, during a short menstrual cycle, ovulation may happen around day 7 after a shortened follicular phase, butting up against the end of a woman’s period.

Second, sperm are able to live in the female reproductive tract for 4-5 days. This means that, especially for women with shorter menstrual cycles, sperm from intercourse that took place during the menstruation phase may remain alive in the body and capable of fertilizing an egg during the ovulation phase. 

Finally, some women experience irregular menstrual cycles, which can make it difficult to predict when each phase will occur. What’s more, factors like stress, medical conditions, and hormonal imbalances can impact the timing of the phases of the menstrual cycle, adding further uncertainty into the equation.

Therefore, if you are sexually active and you want to avoid pregnancy, it is a good idea to use a contraceptive method such as condoms, birth control pills, or an intrauterine device (IUD) to prevent pregnancy from occurring at any point of your cycle. On the other hand, if you are trying to get pregnant, it is helpful to have intercourse at multiple points throughout your cycle, including but not limited to the ovulation phase.

References:

• Salgado, S., Gutiérrez, S.A., & Goosman, C.A. (2022, March 15). Can I get pregnant while on my period? https://www.invitra.com/en/can-i-get-pregnant-on-my-period/
  
  
• Stanford, J.B., White Jr, G.L., & Hatasaka, H. (2002). Timing intercourse to achieve pregnancy: current evidence. Obstetrics & Gynecology, 100(6), 1333-1341. https://doi.org/10.1016/S0029-7844(02)02382-7