Mr. Handler and Ms. Brown posted the announcement the day before the president of Planned Parenthood, Cecile Richards, testified on Capitol Hill over what she called “outrageous accusations” by Republicans who said that her organization profits from the sale of fetal tissue. In the hearing on Tuesday, she called the charges “offensive and categorically untrue.”

Mr. Handler is the author of “The Dark” and “A Series of Unfortunate Events.” Ms. Brown is an illustrator and educator and the author of books including “How To Be.”

Two days after the announcement was posted on social media, it was shared widely by readers who supported the donation. It also drew the attention of abortion opponents.