This is found primarily in the Sunni hadith collection of al-Bukhari. (I am not saying the idea has never been adopted by any Shi'i but this is the main reference.)
In the Shi'i hadith book Man La Yahduruhu al-Faqih, it is related that al-Fudayl asked Imam al-Sadiq (A), "The people are saying that most of the people in Hell will be women." Imam al-Sadiq said, "How could that be true, when a man can marry a thousand women from this world there, in a castle of pearl." (Ok maybe this might be a little strange to some people, but the point is, he is refuting it.)
Anyway, the idea that more women or more men will be in hell contradicts the ethos of the Qur'an, which does not judge people by gender, ethnicity, origins, etc, and instead judges people based on their inner purification/beliefs and outer deeds. The tone of this hadith also contradicts what is known of the character of the Prophet (S). The Prophet (S) was so shy that he hesitated to say "no" to someone or criticize someone unless necessary; why would he rail against women? This is more like the way ordinary people talk to each other - in particular, women when they complain about men, or men when they complain about women.