Just after founding the city of Rome, Romulus tried to increase the number of its citizens. He didn’t hesitate to use any means necessary to achieve his goal. He established an asylum to attract the fugitives of neighbouring towns (often criminals), devised a plan to seize the women from a neighbouring tribe called Sabines, but he also had to ensure that the children born in the new city survive.
It seems to be customary in those times, that people could just refuse to take care of their children and simply let them die. This was especially true about the unfortunate children that showed signs of a disability or illness upon birth. There is a documented practice of killing them in Sparta and Rome seems to be no different. But the cruel practice was not restricted to the disabled ones. Romulus allegedly took some measures to minimize its occurrence and pass a law on that:
“In the first place, he obliged the inhabitants to bring up all their male children and the first-born of the females and forbade them to destroy any children under three years of age unless they were maimed or monstrous from their very birth.”Dionysius of Halicarnassus, The Roman Antiquities, Book 2
Even with the “monstrous” ones, he made things difficult for the parents. He established a rule that such child must be considered unsuitable (and therefore sentenced to death) nut just by the parents, but also by their five nearest neighbours. Dionysius writes about the penalties set for violating this new law and they seem to be strict – one could lose half of their property. On the other hand, the same author also mentions punishment for some other crimes. If you compare it to the penalty for violating the patronage relationship (e.g. a plebeian client suing his patron in court) which was death, killing one’s own child suddenly seems to be a less serious crime.
Dionysius of Halicarnassus – The Roman Antiquities