I don't know much about the statistics from the fathers' side but have done a bit of research on mothers who kill. It is very, very clear from studies of infanticide and filicide by mothers that women in these situations are generally alone, poor, often have repeatedly reached out for help- Michelle Oberman and Cheryl Meyer in the US have done a lot of work on this.
No one can deny that women can abuse children horribly. However, the situations in which they do so are different and reflect social assumptions that women are the default carers (and frequently, the social isolation of lone parents who tend overwhelmingly to be mothers).
given that it is women who are overwhelmingly left in sole charge of children in frequently appalling circumstances, I think that ShriekingHarpy's statistic of 47 percent maternal killers versus 53 percent fathers is very significant.
It is very, very hard to imagine a woman storming in to her ex's house to shoot her children, him and herself dead, because she is not getting enough access or feels insignificant in her former family's life
It is hard to imagine for a reason, because this is generally male behaviour. I am not arguing that all men are murderers, inferior, or wired this way, but the construction of masculinity as control, physical prowess etc sadly dictates different trends in the acting out of violence in the minority of cases where a parent murders children. (Men are FAR more likely to take somebody else with them when they murder children, usually an ex).