Regarding pregnancy, at the completion of how many months is one allowed to tell family, others? When do we start counting from?
One should not publicize their pregnancy until entering the 5th month. This applies only to “publicizing”. One may share the information with close friends and family. Likewise, it’s ok to share the information where necessary.
There was a Minhag amongst Chassidim that until 3 months into the pregnancy one should conceal even telling close family members, including not writing to the Rebbe, but the Rebbe doesn’t mention this anywhere, and in fact – implies otherwise.
These time periods are calculated from the Mikveh night.
See Igrois Kodesh of the Rebbe Rayatz, Vol. 9, p. 290. Likkutei Sichos , Vol. 12, p. 178. Igrois Kodesh, Vol. 3, p. 387 p; 5 p. 221 and more.
.חשבון החדשים מליל טבילה, כפשוט. וראה רש״י נדה ל, א ד״ה ליום מ׳. באה״ט יו״ד קצד, ד. פת״ש שם ג. שיעורי שבה״ל שם