*Naruto Uzumaki is the nine tails Jinchuriki and that Jinchuriki life came with a secret nobody other than Jirayia, Tsunade and Kakashi knew. Since Naruto is the Jinchuriki of the nine tails, he also received one of the Kyuubi's abilities, the ability to get pregnant and give birth. That was due to the nine tails only having women as hosts and therefore when the beast was sealed into Naruto, it gave him the ability which was why his anatomy, internally and externally when it came to reproduction, was female.*