Dr. Alex Hesse (Arnold Schwarzenegger) becomes a reluctant participant in an unusual experiment, as he agrees to be implanted with a fertilized egg, thus making him the first pregnant man. Any mother knows the plot line of this movie, as Schwarzenegger portrays the various stages of pregnancy with all it's mood swings and waddle walks. Danny DeVito plays Dr. Arbogast, the mad scientist who has concocted the idea so that he can prove that his new drug works so well at preventing miscarriages, that even a man can have a baby.
The success of this movie is mostly due to the novelty of Schwarzenegger portraying a pregnant man. There are some truly funny lines in the script and Schwarzenegger knows how to deliver each one so that the humour never seems stretched or unreal. DeVito and the other cast members are also masters at bringing the point home, thus delivering a complete comedy package.
As for showing Junior to the family, there are some issues to consider. Junior does little to encourage the idea that a fetus is a living being. These men are scientists, and the plan is to get the fertilized egg through the first trimester, and then "remove it." It is not until later in the movie that Dr. Hesse becomes emotionally attached to the child, also indicating a flaw in DeVito's character: Why would a doctor, who is spending his life looking for a drug to prevent miscarriage, not be more sympathetic to a developing embryo? The audience is led to believe he is just after the money, but there must be greater fortunes to be made in other discoveries.
Finally, the story involves two couples having children, and neither are married. Two scenes involve sexual situations, one where a couple is given brief instructions on collecting a sperm sample, and another involving passionate actions on a couch. My recommendation is that you view Junior before presenting it to your family to ensure that it meets with your standards and values.