In reality, Lisa Kudrow was no longer pregnant by the time of this episode. Her son Julian was born on May 7, 1998, thus her belly was fake.
Debra Jo Rupp, who recurred as Alice, was given time away from her new role as Kitty Forman on That '70s Show (1998) to appear in this episode.
During one scene's recording, writers were finding it tough to come up with an alternative word for 'vagina', which might upset the network when the show aired. The cast didn't take it very seriously and Matt LeBlanc dared Lisa Kudrow to say a very crude word instead. Kudrow explains that Jennifer Aniston, David Schwimmer and co. agreed to pay her $100/$200 each for the brave endeavor.
When giving birth to triplets, women typically have a Caesarean section to prevent complications that can arise during a natural birth. The show had Phoebe go through natural birth most likely because C sections were not allowed to be shown on TV.