Are they not going to bring up that there is more then just rd that he knocked up. Its a min of three and I don't believed he stoped there.

Also its very sweet that pinkie swaps with granny smith.

11246272
Well, it's a possible three or more, and I'm sure that now that theyve told Bow he'll be made to check in with them.

However...

"B-but pregnancy control is supposed to be a mare's responsibility," Windy argued. "I always took care of myself first at parties like that. Any mare knows that the responsibility lies with both, but the risk is hers alone to bear, so..." she trailed off.

Okay, I REALLY hope that's Windy phrasing it badly, but this raises a key question:

Do the mares know that THEY aren't on some form of birth control at the time?

Because if all they know is "it's taken care of," Twilight is in HUGE trouble once they learn she's only been sterilizing one side of the equation.

11246640
This is actually addressed in the prequel as part of the body swap ritual, though not as deeply as might be desired.

Short version if you don't want to (re-)read it: Everypony who is at the party on time is told directly that the stallions are temporarily sterilized for the duration of the body-swapping ritual. The not-overtly-stated but intended 'read between the lines' is that this is intentional. And Twilight is, indeed, being foolish by relying on that, as is seen here.

11246649
Okay, I see now - somewhere in there, I just blipped that they tell everypony. Less "what were you thinking" then, but Twi, sweetie, you had BETTER come up with a better design nest year....

Rainbow began shaking uncontrollably. Her dad might have knocked her up?!

Honey, I might have impregnated the kids