Prayer is so powerful that it can rip up a decree of childlessness and break through whatever is blocking conception, as it is written: “Yitzḥak pleaded with the Lord on behalf of his wife, because she was barren; and the Lord responded to his plea, and his wife Rivka conceived” (Bereishit 25:21). The Sages say that Yitzḥak and Rivka recited many prayers and had the same goal in mind. The phrase translated above, “on behalf of his wife,” is “le-nokhaḥ ishto,” which can also be translated as “facing his wife.” These words teach us that:
Yitzḥak prostrated himself in one corner and Rivka prostrated herself in another. He said, “Master of the universe, may all the children You give me come from this righteous woman.” She made the same request: “May all the children You give me come from this righteous man.” (Bereishit Rabba 63:5)
Yitzḥak said, “Why were the patriarchs and matriarchs infertile? Because God craves the prayers of the righteous” (Yevamot 64a). This must be elucidated: The prayers of the righteous help open the gates of blessing for the entire world. Were the righteous to enjoy the good life they deserve, they would not pray for the rest of the world, which would be left to suffer. Since God wants the best for the world, He craves the prayers of the righteous, which connect the world to its source, thus changing reality for the better. The gates of heaven open, raining down blessing on the whole world. As a result, everyone dealing with the same type of difficulty as the righteous is delivered along with them.
Similarly, the Sages say, “When Sarah conceived, many barren women conceived as well. Many deaf people started hearing, many blind people started seeing, and many of the insane became sane” (Bereishit Rabba 53:8). This explains Sarah’s statement, “God has brought me laughter; everyone who hears will laugh with me” (Bereishit 21:6). For, to a certain extent, all were healed with her.
There are times when it is a person’s destiny to bring a brand new soul into this world, a soul whose mission is to move the world forward. Since this soul is so new that it has never entered the world, it faces many obstacles. The angels in heaven object that the world is not worthy of advancing to another level. Therefore, the people who are meant to give birth to these souls suffer from infertility. Through their process of purification via repentance and prayer, they open the gates of heaven and are privileged to give birth to new souls.
The midrash (Bereishit Rabba 45:4) presents another perspective on the difficulty the righteous have in conceiving. To explain why Hagar conceived Yishmael immediately, while Sarah had to wait a long time to conceive Yitzḥak, R. Ḥanina b. Pazi offers an interesting image: “These thorns are neither planted nor tended, yet they grow rapidly of their own accord. In contrast, how much pain and toil are necessary to make wheat grow!”