Judaism: "Be Fruitful and Multiply"
The household’s of Abraham and Isaac were plagued by numerous setbacks. Many painfully childless years passed before the Matriarchs Sarah and Rebecca bore children. The world was not yet ripe for welcoming Abraham's offspring. Abundant prayer and spiritual refinement ("tikkunim") would be necessary before the "gates were opened," and Isaac and Jacob could be born. Jacob himself was not quick to establish a family. Who knows, this may well have been one of the reasons Isaac so loved his son Esau - the prosperous, "skilled trapper" - and wished to bless him. While Esau was busy creating a large family, Jacob still gave the appearance of being an innocent and inactive tent-dweller.
According to the Midrash, it was not until the age of sixty-three that Jacob was sent by his parents to find a wife in Charan. He then proceeded to tarry for another fourteen years in the academy of Shem and Ever, finally reaching Charan at the age of seventy-seven. It then took Jacob another fourteen years before he finally managed to wed both Leah and Rachel.
Yet, after all the preparations and setbacks, the ground is finally made fertile, and all Jacob's sons follow faithfully in their father's path. The efforts of three patriarchal generations pay off: Unlike Abraham who fathered Ishmael, and unlike Isaac who fathered Esau, Jacob's "bed is perfect," his seed is flawless.
Indeed, when the time came, when all the preparations were completed and the barriers removed, the House of Jacob grew in leaps and bounds -- twelve boys and a girl in one generation. By the time the Egyptian Exile came to a close, Jacob's offspring had become a great nation numbering some six hundred thousand army-aged men, the entire nation reaching a total of three million. All of the painful preparatory stages paid off.
"Be Fruitful and Multiply"
The Torah commands every man to father at least one boy and one girl (Yevamoth 61b). Supporting themselves upon the verse "He did not create chaos; He formed it to be inhabited" (Isaiah 45:18), the Sages added a Rabbinic ordinance to have even more children. In other words, the purpose of creation is to add life, and every Jew is called upon to take part in this goal.
In addition, the Sages taught that even if one managed to fulfill his obligation to have children while still young, he should continue having children when he is older, as the verse states, "In the morning sow your seeds, but in the evening do not allow your hand to rest, for you cannot know which one will be worthy - this one, the other, or both of them" (see Yevamoth 62b).
Boy and Girl - An Absolute Obligation
Regarding the Torah commandment to have both a boy and a girl there is no room for leniency. Every man must do whatever he can in order to fulfill this obligation. It is told of King Hezekiah, who was exceedingly righteous, that when he saw in his divinely inspired vision that he was destined to give birth to a wicked son, he refused to marry. This step was regarded as extremely unacceptable in the eyes of God, so much so that Isaiah the Prophet was sent to warn Hezekiah that this sin would cause him not only to die in this world, but to forfeit his portion in the World to Come, as well. From here we can see that every Jew is commanded to give birth to at least a boy and a girl, regardless of how righteous or sinful they may eventually turn out to be. In the end, Hezekiah repented and married the daughter of Isaiah the Prophet, and indeed had an evil son - Manasseh. All the same, through Manasseh the chain of the House of David was able to endure.
Beyond Boy and Girl
One might reason that, because the obligation to have additional children beyond a boy and a girl is only a Rabbinic ordinance, it is of lesser importance.
The opposite, though, is true. It is impossible to overestimate the importance of this obligation. If, as the Sages of the Mishna teach, "A person who manages to preserve even one Jewish soul is treated by the Torah as if he had preserved the entire world," how much more so one who gives birth to and raises a Jewish child. It is also possible to grasp the profound importance of this Mitzvah when one considers the Torah commandments to act charitably and to perform deeds of kindness. Furthermore, one who gives birth undoubtedly fulfills the commandment to "Walk in His ways" (Deuteronomy 28:9), for just as the Almighty created the world, and filled it with life, one who gives birth takes part in this process.
The Rabbinic Commandment
On the face of things, the rabbinic obligation to continue having children even after giving birth to a boy and a girl carries no minimum requirement and every additional child that is born is counted as a Mitzvah. In the words of Rambam: "Though one has fulfilled the commandment of procreation, there is a Rabbinic commandment to continue procreating so long as one has the capacity, for, one who brings an additional Jewish soul into existence is viewed as having created an entire world" (Hilkhot Ishut, 15:16).
There is, though, an opinion that even the Rabbinic obligation has a minimum requirement: to give birth to an additional boy and girl - for the Rabbinic ordinance reflects the Biblical commandment. In other words, according to this view, the intention of the Sages was that an individual not to be satisfied with merely fulfilling the Torah commandment. Rather, every Jew must have two boys, and two girls. Though each additional child is considered a great Mitzvah, once one has two boys and two girls, one is no longer obligated to procreate (Taz, Even HaEzer 1:7; Pri Yitzchak 41).
How Many Children should a Person Have?
The opinion which holds that according to the Sages one must have at least two boys and two girls may prove helpful in guiding a family not interested in being overly stringent, in deciding just how large a family to establish. We might say that average parents, who do not suffer from any unusual health problems and are more or less capable of raising and educating their children, must begin by fulfilling the Rabbinic commandment. Overall, it takes having about five or six children in order to fulfill this Mitzvah.
Only after the goal of two boys and two girls has been reached, does the question of whether to be stringent and give birth to more children, or to invest energy and strength in other important areas, become relevant. Though there is immeasurable value in continuing to parent more and more children, all Torah obligations which add life are, by nature, only general, and not binding on an individual level. Rather, an individual is free to sanctify God's name in some other manner, "adding life" to the world by performing charity and good deeds to needy persons. It should be remembered, of course, that all methods of birth control must be in keeping with Jewish law.
Degrees in Mitzvah Observance
According to what we have said thus far, there are three degrees in the observance of the Mitzvah of procreation: 1) the Torah obligation to have a boy and a girl, which one must do everything in his power to fulfill. 2) The Rabbinic ordinance which states that the number of children in a family which is not interested in being particularly stringent must be somewhere between four and six. 3) The praiseworthy added stringency of having as many children as possible in accordance with the parents' capacity.
How to Gauge Capacity
The "parents' capacity" depends chiefly upon their ability to raise and educate their children. For example, a couple which knows that it is capable of raising even numerous children to be amiable, Torah observant Jews should strive for as many children as possible. Yet, if the parents understand that by having more than, say, eight children, they will be overwhelmed, and all of their days will be filled with aggravation and anger, they should refrain from having more children. True, even in this case, each additional child will be counted as a Mitzvah, yet the added load will merely drive the couple to animosity and transgression, and this will have a negative effect upon the upbringing of their children.
Short- and Long-Term Considerations
A survey that was taken among men and women in Israel's non-religious sector reported that, on an average, young parents are interested in having about three children. In practice, though, most families are unsuccessful in realizing this goal and manage to produce only two. Their long-term goals conflict with their present needs. They would like to have another child, but "this year is not appropriate." A baby interferes with work. It’s a burden. One has to get up in the middle of the night, feed, change diapers, bathe, carry, play, etc. The years pass and before long, time runs out - and there are fewer children than had been desired. In a different survey, the majority of older woman admitted that they regret not having one or two more children.
In fact, it often happens that even religious women, who naturally have many children, regret not having more children than they did while they were capable. A person must strive to overcome weaknesses in order to realize his life goals and reach his full positive potential.
"He, who separates between holy and mundane, may He forgive our transgressions; May He increase our offspring and wealth like dust, and like the nighttime stars."