There is NO nudity in this film.
Antoine Doinel is seen in bed with his wife several times. She has a nightgown on. He is bare chested. In an early scene, Christine says that her breasts are ugly. She opens her gown so that Antoine can inspect them. He says that one is bigger than the other.
An elderly man sees the back of Christine, walking, and comments "I'd lay her badly, but I'd lay her gladly."
When Antoine arrives for a job interview, a man in the office reaches for a woman's chest. She tells him to get lost. He then reclines in his chair and says that if he had breasts, he would fondle himself all day long.
Antoine rubs his wife's legs while she is standing up on a platform, and then puts his hand up to her lower thigh.
A painting in a brothel shows the side of a nude woman; nothing explicit.
A man visits a brothel where women are lined up and he chooses the one he wants A woman is later shown buttoning her shirt in front of the man, implying that she had sex with him.