The fourth season of Friends, an American sitcom created by David Crane and Marta Kauffman, premiered on NBC on September 25, 1997. Friends was produced by Bright/Kauffman/Crane Productions, in association with Warner Bros. Television. The season contains 24 episodes and concluded airing on May 7, 1998 with the double length episode "The One with Ross's Wedding".
Friends season 4 DVD cover
"The One with the Embryos" is the twelfth episode of Friends' fourth season. It first aired on the NBC network in the United States on January 15, 1998. In the episode, Phoebe agrees to be the surrogate mother for her brother Frank Jr. and his older wife Alice Knight. Meanwhile, a display by Chandler and Joey of how well they know Monica and Rachel by guessing the items in their shopping bag leads to a large-scale bet on a quiz, for which Ross acts as the gamemaster.
Lisa Kudrow's pregnancy inspired the story arc for her character Phoebe to become a surrogate mother.