Doonesbury by Garry Trudeau for December 12, 1973
Girl: Mommy goes into the hospital today. I guess I better start thinking positively about my newest sibling... Joanie: Good idea, dear! Girl: I just hope it's a sister. I need a sister! Also, it's more "in" to be a female than a male these days! Much more fashionable. Joanie: It is? Girl: Sure! Girl: I don't think there's any question about it... Girl: It's true. I read it in "Time" last week.