(Newser) – Pope Francis has baptized 33 babies in the Sistine Chapel as part of an annual tradition, this year repeating an invitation to mothers to nurse their babies if crying out of hunger. Francis pronounced each baby's name and poured water from a golden shell-shaped cup on to their foreheads during the ceremony today, welcoming them into the faith. The event marked the end of the Christmas season. The 13 infant boys and 20 infant girls, including a set of twins, were all children of Vatican employees. During his homily, Francis repeated an invitation extended to mothers on the same occasion last year to feed their children, "also now, if they are crying for hunger, nurse them." The annual ceremony is held the first Sunday after the Jan. 6 Epiphany. (Read more Pope Francis stories.)