There is no injustice with Jehovah. We all need to keep in mind that we are all imperfect sinful humans and as such we all do not deserve to be alive. Our children are no different they are born imperfect so Jehovah has the right to take not only our life but our children’s too. It might sound harsh to put it this way, but it is the prince humanity had to paid for following the devil in his rebellion against Jehovah. In reality is Satan the one responsible for the death of children and such. We live the years that we live only out of Jehovah’s mercy.