1 / 8 / 5732
...With regard to the question of birth control which you mention in your letter, I trust you know that generally the Jewish religion opposes it. As a matter of fact, child-bearing is the first Mitzvo in the Torah, Toras Emes and Toras Chaim, the first Divine commandment being, "Be fruitful and multiply." It is only in exceptional cases that Jewish Law permits certain forms of birth control. If you have any question in this regard, you should put it to a practicing experienced Rov and get his ruling, for it is not within the sphere of my duties to Pasken Shaalos.
Finally, let me also observe that the blessing of children is not something which a person may choose at will, but it is a blessing from G-d. Therefore one should very carefully consider even if there were no other motives - whether one should interfere in this area.
I trust that the above lines, though by far inadequate in relation to the subject matter, will suffice to help you put matters in their proper perspective.
With blessing,
Notes and sources
Source: Secretarial carbon copy
Published: Tesurah Wenger-Rosenfeld (13 Kislev, 5786).
Note: This letter is sourced from the archives of Rabbi Nissan Mindel, the Rebbe’s secretary entrusted with transcribing the Rebbe’s orally dictated responses. The archive consists of secretarial copies that may not include the Rebbe’s final edits, as well as drafts and unsent letters.