Some authorities rule stringently that even after a couple has fulfilled the Torah commandment of procreation by having a son and a daughter, contraception is still forbidden, because the Sages ordained a mitzva to have as many children as they can. Therefore, the use of contraception is permissible only for nine months to a year following birth, to allow the woman to recuperate and tend to her baby’s needs. Beyond that, contraception is permitted only if there is a specific health-related need. Contraception because of preoccupation with raising the children or financial constraints is forbidden.
Nevertheless, in practice, as we learned (section 6), the rabbinic obligation can be understood to mean having four to five children, while having more children is a great mitzva but not an obligation. Therefore, until one fulfills the rabbinic obligation, it is best not to use contraception for more than a year after birth. Those who wish to be lenient, to allow more time for physical and emotional recuperation, may use contraception for two years, because for many generations, this was the duration of the natural contraception that resulted from nursing. In cases of illness, as long as the biblical obligation of having a son and a daughter has been fulfilled, contraception may be used for more than two years.
After the rabbinic obligation of having four to five children has been fulfilled, it is permissible to use contraception for an indefinite amount of time if necessary. For example, if a couple knows that they would feel overburdened by additional children, leading to irritability and anger and making it difficult for them to educate their children properly, they may use birth control. If a couple wants to focus on their important, valuable jobs more than they want to have additional children, and they feel they will not be able to do so if they have more children, they may use birth control. If a wife wants to work at a job that will make use of her talents, and having more children will prevent her from doing so and leave her extremely frustrated, the couple may use birth control. Poor people who believe that it will be hard to raise more children without needing to accept charity may use birth control. The couple should weigh all these factors together; if they disagree, they should compromise, as they are codependent partners. It is also good idea to consult with someone wise.
Those who wish to enhance the fulfillment of the mitzva will continue to have as many children as they can, even after they already have five. Even if they use contraception for a year following each birth, it is considered enhancing the mitzva. This is the proper conduct for those who feel that without too much difficulty they can raise more children in the ways of Torah, mitzvot, and derekh eretz, and whose work is not a calling that will be harmed significantly by having more children. A woman at the age of about forty who is concerned about increasing risk may use contraception from then on. This is common even among those who enhance the mitzva.
On the other hand, we find that poskim permitted contraception for several reasons. For example, Rema says that if a man’s wife died and he already has many children, and he is concerned that if he marries a woman of childbearing age, quarrels will erupt between the two sets of children, he may marry a woman who is no longer fertile (Rema, EH 1:8). Terumat Ha-deshen §263 states that after a man fulfills the mitzva of procreation, he may marry a woman who cannot conceive. It is possible that Rambam feels that the mitzva for a man to marry a woman of childbearing age is only on condition that he has the energy to educate and support the children; Rambam’s formulation is “as long as he has the energy” (MT, Laws of Marriage 15:16). Along the same lines, AHS 1:8 qualifies, “if his economic position is good enough to support them.” Moreover, the Talmud relates that after R. Ḥiya’s wife had two sons and two daughters, she drank a sterility potion and did not conceive again (see the next note). From this story, many have concluded that after fulfilling the Torah obligation, a woman may take indirect action to prevent further pregnancies, even without a compelling reason to do so (Igrot Moshe, EH 4:74:1-2; Tzitz Eliezer 9:51:2; R. Elyashiv, Kovetz Teshuvot 3:174). It is possible that there is no major disagreement here. Even those who are lenient would agree that there is a mitzva to have as many children as possible, and even those who are stringent would agree that people who wish to use contraception in a way that does not violate any prohibition (as explained in the next section) may do so, though they generally instruct their students to act more piously.
In practice, as I wrote in section 6 above, the mitzva has three tiers of obligation: a) the Torah commandment to have a boy and a girl; b) the rabbinic obligation to have four to five children; c) the non-obligatory mitzva to have additional children. In addition to the specific sources cited for this division in n. 6, this structure gives expression to all views – the stringent opinion in the second tier and the lenient opinion in the third. In truth, even within the second tier, some maintain that four children are sufficient even if they do not include two sons and two daughters, while others go further and have five children, or continue to have children until they have two sons and two daughters. Within the third tier (six children or more), there is variation as well. The more children a couple has, the greater their enhancement of the mitzva.
At first glance, this division of the rabbinic mitzva into two tiers – the obligatory and the optional – is an innovative division for which there is barely any source in the halakhic literature. Nevertheless, it seems to me that one who scrutinizes the rulings and guidance of the poskim will find that this comports with their mainstream guidance: Early on, when a family is relatively small, they instruct the couple to be stringent and not to use contraception unless there is a great need for it. Once they have many children, poskim are lenient and allow contraception even when there is no great need for it. Thus, we see that the division of the mitzva into three tiers gives expression to what poskim have accepted. Moreover, this structure is effective as it gives the posek and the couple a rubric; until a couple have four to five children, which is the norm for most religious families, it is best for them to incline toward the opinion of the stringent poskim who rule against contraception unless there is a particular need. From that point on, they should incline toward the permissive view.
As we explained above in n. 5, the rabbinic obligation is not as strict as the Torah obligation. Before the latter has been met, no ona may be skipped; after the fulfillment of the obligation, according to most poskim, a couple may forgo some onot (SA EH 76:6). Therefore, the mainstream position is that before fulfilling the Torah obligation, a couple may not use contraception for more than a year unless there is a serious need for it; after they fulfill the obligation, it is preferable not to use contraception for more than a year, but those who wish may be lenient for a period of two years.