Filliacide, the killing of daughters, is not a very elegant word, but neither are the terms gendercide or femicide.  But these newly coined expressions are not as ugly as the phenomenon they describe–the selective killing of female fetuses or newborn girls solely because of their sex.  It is not a new practice–excavations of ancient Roman sites show sewers clogged with the skeletons of newborn girls, according to Rodney Stark.  John Hobbins reports these and other gruesome details of the ancient and modern practice at Ancient Hebrew Poetry.  John also points out how one factor in the history of the world has curbed the practice of killing girls because they are girls,  and that factor is the spread of the Christian faith.