Is it true that many religious women will not tell anyone except for close family about their pregnancy until it's obvious? And that they won't tell anyone their due date, either!



There's no law at all to that effect, but it is a custom in many religious circles. This doesn't necessarily apply to grandparents and members of the immediate family, although some will wait until after the first trimester to tell even siblings. For the rest of the world, many hold off until they enter the fifth month.

Just a generation ago, one's personal pregnancy was not yet a subject for public discussion—in the general population, not just Orthodox Jewish circles. So essentially it's really just a matter of personal privacy and discretion—no different from other states-of-the-body-that-are-nobody-else's-business.

One component of this practice also seems to be concern over ayin hara – the Evil Eye. For the same reason, you will traditionally not see Jewish women having baby showers, decorating the nursery, or even buying anything for the baby before the birth. (We have a few articles about the Evil Eye here. Especially, read Do You Believe in the "Evil Eye?")

There's a practical component to this, as well: Most miscarriages (G‑d forbid) take place in the first trimester, and the baby's heartbeat is usually discernible at around the time the pregnancy becomes noticeable. So a woman doesn't "go public" about her pregnancy until the chances are good that she will indeed carry it to term and G‑d willing deliver a healthy child.

Regarding not revealing one's due date: That's just to avoid the really annoying calls - "just checking on you" - and comments - "you're still around?!" - that start coming right around the due date.