It is natural in the New Testament for adults to be the candidates of water baptism because many converts were made, and mostly adults. There is little or no discussion about child conversion.
If one, however, follows through with the concept of circumcision and infant baptism, then only males are candidates.
In many churches who practice infant baptism, the emphasis is not on the candidate as much as those presenting the child. It is not efficacious for salvation, but rather dedicating the child to Christian instruction leading to a conversion experience. "Bring up a child....."
Those who follow covenant theology tend to sprinkle infants, but follow through with a confirmation....a time when one of an age of understanding studies the scriptures regarding knowing the Christ as Saviour. Certainly modernism has tainted these doctrines, but does not change the early facts of what they meant.
Even Queen Elizabeth I was immersed, as an infant, but it was common practice in Anglican Churches. Even to-day, many of the old Anglican Churches have a dunking tank somewhere in the building, often under the pulpit area.
So, we generally believe scripture teaches that only a twice-born believer is the proper candidate for baptism as a step of obedience, and immersion taken from the actual Greek word, which means to dunk or immerse.
Cheers,
Jim