If a woman does not have a veset kavua, we don't know exactly what triggers her period. Therefore, there is a halachic concern that she might menstruate in response to intercourse. This phenomenon, which is extremely uncommon and almost always treatable, is known as roah mechamat tashmish. If it were ever to occur consistently, the couple would not be permitted to have a physical relationship and the marriage would have to be dissolved.
To reduce concern about roah mechamat tashmish, many poskim recommend that a bride without a veset kavua establish a chazakah (halachic presumption) that marital relations with her husband do not cause bleeding. Other authorities do not require this procedure unless the couple has already found blood following relations. Each couple should ask their own rabbi how to proceed.
The chazakah is established as follows. On three occasions, the wife does a bedikah prior to intercourse. After intercourse, she does another bedikah and the husband wipes himself with a bedikah cloth to check for blood. If they follow this procedure three times in a row without finding blood, they have established a chazakah that intercourse does not cause bleeding.
The purpose of these bedikot is to check for uterine bleeding, not hymenal bleeding. Therefore, a couple should not begin this series of bedikot until they are certain that there are no traces of dam betulim. They should wait until intercourse has become completely comfortable – both physically and emotionally.
This chazakah applies specifically to a woman without a veset kavua, who is liable to menstruate at any time. Therefore, a woman does not do these bedikot at stages of her life when she is expected not to menstruate. These include:
- If she has a veset kavua, either natural or hormonally induced.
- If she is using hormonal contraception (while taking the active pills, or when the patch is on or the ring inserted)
- If she is halachically considered mesuleket damim (amenorrheic – not expected to menstruate). This applies if she is pregnant (me'uberet) or if she is breastfeeding (meineket). (According to some authorities, a woman considered a meineket for this purpose for two full years postpartum, whether or not she is actually nursing. According to others, she is considered a meineket only until she resumes regular periods postpartum.)
Furthermore, most women without a veset kavua do have a somewhat predictable pattern. Typically, a woman might know that she will not get her period until a certain interval has elapsed from her previous period. For example, she might know that she never menstruates before day 24 of her cycle. This is called a veset chatzi kavua, a semi-established pattern.
A woman who has such a pattern will do bedikot before and after intercourse only on days when she could conceivably menstruate – in our example, from day 24 on. (Of course, on days when she is halachically considered most likely to menstruate – onot perishah – the couple abstains from relations and the bedikot are not relevant.) Before day 24, however, she is similar to a woman with a veset kavua. She is expected not to menstruate and is exempt from the bedikot.
In practice, many couples never actually do these bedikot. Here is a typical scenario:
A kallah takes birth control pills starting a few months before her wedding to regulate her cycle. She establishes a veset kavua on the pill. Shortly after she goes off the pill, she gets pregnant. By the time her baby is two, she is pregnant again. By the time that baby turns two, she is back on the pill. And so on. A woman can spend years alternating between pregnancy, breastfeeding, and hormonal contraception without ever being required to do these bedikot.
If a couple ever does find blood after intercourse – when doing these bedikot or on any other occasion – they should consult a rabbi as soon as possible. Such situations can almost always be resolved; however, a delay in asking the question could make the problem halachically much more serious.