In Biblical Law, conjugal rights are explicitly granted to the wife. The Tora indicates in Exodus 21:10 that the husband "must not deprive his wife from her food, her clothing and her marital rights".
In the words of Maimonides, a husband's consistent refusal to engage in sexual relations, i.e., when deliberately and/or maliciously the husband deprives his wife from intimacy is considered a transgression of a Biblical prohibition and the woman has legal grounds to ask for her divorce, claiming the full amount of the financial compensations established in the Ketuba. This does not apply, however, when the reason for the husband's abstinence is health-related or so. (Maimonides MT, ishut 14:7)
The wife has the legal rights to prevent his husband to go in a long trip (in ancient times, men use to go overseas for business for years) because that would deprive his wife of her conjugal rights (14:2). The Talmud also discusses the frequency of sexual obligation based on the husband's occupation (14:1).
Although not based on a specific Biblical statement, the wife is also expected to fulfill her conjugal duties. And a wife who without a justified reason (kede leṣa'aro) permanently denies from her husband his conjugal rights is called a rebellious wife (moredet) and, in case of divorce, she is not entitled to any compensations (14:9).
It is important to clarify that the primary purpose of this Miṣva, sexual intimacy, is to reinforce the loving marital bond between husband and wife. In a separate Miṣva the Tora indicates the commandment of having children (see here) but this Miṣva, 'ona, is independent from the intention of procreation. When conception is not possible, such as during pregnancy or when the woman is under a permissible form of birth control, or after the wife is no longer able to bear children the couple is still expected to have an active sexual life.
