From Muppet Wiki

That's Life was a musical comedy series which ran on ABC from September 24, 1968 through May 20, 1969. The series starred Robert Morse and E. J. Peaker as a young couple, following them through courtship, marriage, and childbirth, with many celebrity guest stars from stage and television.

The Muppets guest starred in the December 3, 1968 broadcast entitled "Bringing Baby Home," in which they performed a version of their Glow Worm sketch. Other guests on the series included many future Muppet Show guest stars, such as George Burns (as Cupid), Tony Randall (as old boyfriend Rodney Wonderful), and Ethel Merman.