LONDON — For four days in 2018, Veronika Didusenko was hailed as Ukraine’s most beautiful woman.

But it wasn’t quite as simple as that. When the organizers of the Miss Ukraine competition found out that she was divorced and had a son, they stripped her of the title — and the $12,000 prize money — saying she had broken the rules.

Now Ms. Didusenko, 24, is suing the Miss World organization, with which the Ukrainian competition is affiliated, saying that the entry requirements — including that contestants be unmarried and childless — are a form of discrimination.

Ms. Didusenko announced the legal action in an Instagram post this week, writing that the entry policy operated by Miss World was “discriminatory on various grounds, namely marital status, and pregnancy and maternity.” In the post, she added that she only wanted to change the rules, not to have her Miss Ukraine crown back.

Miss World said in a statement on Wednesday that Ms. Didusenko had been disqualified because she “gave false information on her application.”