maternity leave = 出産休暇
この冗談全部英語にするとこうなります：
A: She's pregnant and she's taking the day off to stop by the hospital and give birth. I think she'll be back tomorrow.
B: So she'll take a one-day maternity leave?
take a/the day off: １日休む
stop by: 〜に立ち寄る
give birth: 出産する
アメリカ合衆国 
