MIL was visiting and had stopped with DH to get a bottle of wine. As they were choosing the bottle, MIL had said something about me drinking Merlot, so DH had started smiling. MIL had inhaled and gone "is she pregnant?". DH had said yes (whilst smiling) and she shrieked "AGAIN?" (DS was 18 months at the time I got pregnant, we've been together for 10 years and married for 3 years) and then complained that she'll have FOUR grandchildren, as if that's really horrible. DH just told her we're not expecting any financial or other support from her...
MIL hates me though, so I wasn't exactly thinking she'd be overjoyed. Strangely, she didn't mind us getting married, but when I got pregnant it all changed, as if I'd "trapped" her DS... I guess you can always get divorced, but you can't un-do children. She also told us (the first time around) that she's too young to be called a grandma, she was 65 at the time.
The reactions that upset me the most was a friend (who had encouraged me to TTC) looking really hacked off and saying "but you didn't even put your time in trying!" and my Dad replying to "you're going to be a Grandad" with "but your step-sister has just had a mc"... as if we'd got pregnant just because we're insensitive (I hadn't even known she'd been pregnant).
All in all, each time, we've ended up feeling like we should just keep the pregnancies and births quiet and not make too much fuss.