At some point when they were West Coast Avengers, Bobbi got pregnant, and she and Clint were really looking forward to having a kid, to the point where they worked out when the kid would have been born.
Bobbi: Before all of this, when we were Avengers, a couple of years ago... I-I had a miscarriage. We didn't tell anyone. Me and my husband, we figured his or her birthday would have been October 12th. We really wanted that kid. And October 12th... That... would have been a nice day.