Trying to remember the title of a movie?

Possibly 70s/80s movie about a guy (Matthew Broderick?) who meets a girl at a nightclub but loses her phone number. He has to go through every number in the phone book to get it back, and they meet up and start going out. The film is mainly about sex and there is definitely a sex scene somewhere in a log cabin. There's a narrator and the films stages are basically about human reproduction. It's been a long time since I saw this so details are very sketchy. Thanks!