Why Sexual Intercourse During Menstruation Is Prohibited?

Copulating with women in this state, in addition to being revolting, also entails great harm and this is a fact that has also been corroborated by present-day medical studies.

Some of the harms are:  Possible occurrence of infertility in the man and the woman, creation of an environment conducive to the development of microbes of sexual diseases such as syphilis and gonorrhea, inflammation of the female genitals, entry of the menstrual matter – replete with microbes from within the body – into the male reproductive organ and several other detriments, which are mentioned in books of medicine. It is for this reason that doctors prohibit sexual intercourse with such women.

The bleeding during menstruation is related to the congestion of the uterine vessels and the flaking of its mucus; the ovaries too are in tune with these vessels in this act of congestion.

Almost contemporaneous to menstruation the female ovule passes through the fallopian tube and enters the uterus so that, in the eventuality of the arrival of the male sperm, the two, in collaboration with each other, can form the embryo.

Initially, the abovementioned blood discharge is colorless and irregular but soon becomes red and regular till, near its conclusion, it once again becomes light in color and slips into irregularity.[1]

Basically, the blood that is discharged every month during menstruation is the blood that gathers in the internal uterine vessels for the presumptive nourishment of the embryo. We do know that every month a woman’s uterus produces one ovule and simultaneous to this the internal vessels, gearing themselves up for the purpose of nourishing the embryo, become replete with blood.

If the ovule, having entered into the womb after having passed through the fallopian tube, encounters the male spermatozoid, an embryo is formed and the blood present in the vessels is utilized for its nourishment. But if not, the blood, as a result of flaking of the womb’s mucus and the rupturing of the walls of the vessels, gets discharged from the womb in the form of menses.

Thus, it becomes plainly apparent as to why copulation in such a state is detrimental and prohibited. The womb, during this discharge, does not possess any kind of natural preparedness to accept the spermatozoid and thus comes to suffer harm.[2]

The Islamic law, if a woman and her husband doubt whether or not the woman’s menstrual blood has stopped flowing and they have sexual intercourse

If one doubts about whether a woman has started seeing menstrual blood or not, she is treated as not being in her menses. However, if it is after menstrual period (assuming that her period lasts for less than 10 days), because of seeing certain signs of being in menses, she doubts whether her period has ended or not, she is treated as being in her menses. Hence, in the given situation, there is objection in having sex.
What Follows are Some grand religious authorities’ answers to this question:[3]
Grand Ayatollah Khamenei (may Allah grant him long life):
It is not permissible to have sex when wife is in her menses. If he has sexual intercourse, it will make kaffara (penalty) mandatory but if they have no knowledge of the menses (and they have sex), they would be under no obligation.
Grand Ayatollah Makarem Shirazi (may Allah grant him long life):
If no blood is seen, there would be no problem in having sexual intercourse.
Grand Ayatollah Saafi Gulpaigani (may Allah grant him long life):
If they have doubt whether the woman has started seeing menstrual blood and they have sexual intercourse, there is no problem and they will not be liable to kaffara also.
Ayatollah Hadavi Tehrani (may Allah grant him long life):
Insofar as they are not certain that the woman is in her menses or when a woman is not in the days of istizhar[4], there is no problem in having sexual intercourse.

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References

[1] I’jaz-e-Qur’an, pg. 55, 56

[2] Tafsir-e-Namunah, vol. 2, pg. 92

[3] The question has been sent by IslamQuest website to the offices of the grand Ayatollah Khamenei, Ayatollah Saafi Gulpaigani and Ayatollah Makarem Shirazi – may Allah grant them long life.

[4] Istizhar means for a woman to consider herself ha’idh (on her period) and observe the rulings pertaining to ha’idh women (to refrain from worship and stay away from the acts that have become haram for her as a result of haydh) until things clear up (meaning that she has to wait and see if the blood exceeds ten days or not and in this time period she can’t pray or fast at all and has to refrain from the acts that are haram for ha’idhs).