1980s or 90s Thriller with simultaneous plots that merged in a twist – What’s the name?

I remember bits and pieces of the movie, seems like I saw it on TV, but don’t think it was a made for TV type movie. Two separate story lines, one was a woman and her husband were trying to get pregnant but couldn’t. Husband was a professor or a psychiatrist, something brainy. Don’t think the woman worked. Other story line was about a love affair. Don’t remember much else about it. May have been that both husband and wife were having an affair. One defining scene that I remember vividly was the husband took a mistress to bed and she got poked by a hypodermic needle in the bed that turned out to be hormones that his wife was taking to suppress her being able to get pregnant. The two storylines resolved into one by the end of the movie, but I don’t remember how. I do remember sitting in stunned silence because I never saw it coming and I usually do, so it was brilliantly done.