Nosy people or just gossipers...?

Have you ladies experienced any nosy people (typically women) who are always trying to figure out f you or someone else is pregnant? I seem to know (and am related to) a few women who are always playing detective: trying to determine if someone is pregnant. Seeing if they drink alcohol, whispering behind their back... I truly don't understand this. If someone is pregnant and not saying it yet; there's obviously a reason and privacy should be respected. My question is what do they gain by doing this? Are they just nosy and gossipy? The one girl I'm speaking of now has 3 kids, so it's not like she's trying and having difficulty. I don't understand why people don't just support one another. Especially if they have been pregnant before and are familiar with the risks of early miscarriage...