While "notifying" that you "are" pregnant, according to data and calculations seems helpful, the fact that a lot of apparent pregnancies end in miscarriage[0], or just the emotional roller-coaster that is family planning (particularly when it requires additional medical assistance) takes a toll on people, means that these well-meaning emails can really be a negative trigger.

[0] https://www.webmd.com/baby/guide/pregnancy-miscarriage

"According to the March of Dimes, as many as 50% of all pregnancies end in miscarriage -- most often before a woman misses a menstrual period or even knows she is pregnant. About 15-25% of recognized pregnancies will end in a miscarriage."