Drs Alex Hesse and Arbigast invent a new type of drug to prevent women from miscarriage. Their funding is withdrawn, mostly bacause of Dr. Arbogast's silly remarks; the are not allowed to conduct human experiments either.
They still want to test the drug, so they decide to make Dr. Hesse pregant - just for a short while. Dr. Arbogast steals an ovum from the heir of their funding (Diana Redding, a nice, but very absent-minded lady); they mix it with Hesse's sperm and put the embrio into Hesse's belly.
Though they wanted the test to go on for just a few weeks, Hesse doesn't want to end it when that time comes - he starts to love the baby, he wants to have it. Arbogast thinks he's stupid, but he agrees to help him.
When Hesse is in the 5th month, he and Dr. Redding start to go out together, and of some things Redding says, Hesse finds out where the ovum is from. He tells it to Redding, who is furious about it.
The dean of the biological department finds out thet Hesse's pregnant, and as it is a very promising experiment (for both the university and himself), he wants to capture Hesse to show him around later as the pregnant men.