ST I, q. 99
Of the Condition of the Offspring as to the Body
We must now consider the condition of the offspring—first, as regards the body; secondly, as regards virtue; thirdly, in knowledge. Under the first head there are two points of inquiry:
(1) Whether in the state of innocence children would have had full powers of the body immediately after birth?
(2) Whether all infants would have been of the male sex?