Halakha prohibits the wasting of seed, so even when contraception is permitted, it is prohibited to prevent pregnancy by means of coitus interruptus (above, 4:1 and n. 1). Likewise, having sexual relations with a condom is prohibited, for the man ejaculates into the condom, thereby wasting his seed.
However, it is permissible to prevent pregnancy indirectly, by means of two main methods: a) taking birth control pills; b) inserting an IUD (intrauterine device). These are considered the most effective contraceptive methods and the most halakhically preferred, because the prevention of pregnancy takes place in the body of the woman, and indirectly, with no harm done to the sperm. Therefore, when birth control is permitted, these methods are permissible according to all opinions (as explained in section 18).
There are two other methods which are less effective in preventing pregnancy and also less preferable halakhically: a) spermicide (foam or vaginal suppository); b) diaphragm. (In section 19, we explain how these methods work.)
In discussing when contraception is permissible le-khatḥila, we were assuming use of the pill or an IUD. However, permission is granted only be-di’avad for a diaphragm or spermicide. Those wishing to use them must have a more compelling reason to do so (as explained in section 19).
Women who are fortunate to be able to rely on nursing for contraception are free of all the concerns and side effects accompanying the various methods of birth control. Therefore, if a woman is not afraid of becoming pregnant soon after giving birth, it is recommended that she not use contraceptives while nursing. If while nursing she does not menstruate or get pregnant, she will know that nursing works for her as a means of contraception. Then, after subsequent births, she can prevent pregnancy by nursing without any need for the pill or to have an IUD inserted. Nonetheless, if someone is worried about getting pregnant while nursing, she may use contraceptives for a period of nine months to a year after giving birth.
As a result of Rabbeinu Gershom’s ordinance prohibiting polygamy and disallowing divorce against a woman’s will, when a woman marries, she is in effect agreeing to partner with her husband in the fulfillment of the mitzva of procreation (section 14 above). Consequently, decisions about contraception, and certainly sterilization, must be made jointly. This is the position of Ḥatam Sofer, EH §20, cited in Pitḥei Teshuva 5:11. Nevertheless, even if the wife drank the sterility potion without halakhic sanction, as long as they are married the mitzva of ona still applies to them.
In any case, we see from the story of R. Ḥiya’s wife that when contraception is achieved indirectly within the woman’s body, and there is no barrier between the sperm and the uterus, there is no concern that seed is wasted. Therefore, there is no problem of wasting seed when using birth control pills or an IUD; the question is whether it is permitted despite the neglect of the mitzva to procreate. However, the poskim disagree regarding the use of spermicides or diaphragms which block the sperm from reaching the uterus. Even though most poskim are lenient, le-khatḥila it is preferable to defer to the stringent opinion. Thus, the use of these methods is be-di’avad, as explained below in section 19 and n. 19.
There is general agreement that the use of a condom is forbidden. Regarding someone with AIDS, see 6:4 below.
. It can be suggested to a nursing mother to use spermicidal suppositories until her period returns. Even though we have seen that this method of birth control is be-di’avad, there is a good chance in this case that nursing itself is preventing pregnancy, so the use of a spermicide is less problematic. The nursing is the primary contraceptive, while the spermicide simply bolsters its effectiveness. If the woman does not get her period at all while she is nursing, then following the next birth she can rely only nursing alone. If she is still concerned, she can use a spermicide until her period returns.