There is no doubt that many people reproduce with the intention of loving their children. Unfortunately not all, but certainly many. The point is that it is really not enough. It is not enough so as to prevent children from serious harm, to prevent children from causing serious harm to others, and to relieve parents of responsibility for serious harm.
People are aware that their children will experience at least some serious harm in their lifetime. It is not something unknown or unexpected, on the contrary, it is completely known and expected. So much so, that there is no life without at least some serious harm. Everyone knows this in advance, and is therefore responsible for the harm that will be caused to their children, even if they will not cause it directly.
Once someone is aware that there may be serious consequences for their actions, they are responsible for them if indeed the consequences are severe.
Others prefer a slightly different wording, which is that failure to prevent foreseeable harm is equivalent to causing harm. Although not the same level of severity, but it is definitely complicity in the offense. In any case, the principle is similar and it is also, or even especially, valid in the context of reproduction because people are aware that there are risks and take them anyway, or alternatively, people can certainly anticipate that harm will be caused to their children if they create them, and they do not prevent them. And another reason that this principle is especially valid in the context of reproduction is that people reproduce out of choice, not out of compulsion or out of a choice between options that all have risks. You can choose not to put someone in a vulnerable place. You can choose not to risk someone else’s life. It is possible not to act without the consent of someone else, and if you choose to do so, you have to take moral responsibility for this decision. But unfortunately in the case of reproduction it is not possible because after the damage is done it cannot be repaired retroactively. You can’t undo someone’s vulnerability after they’ve already been created. Existence is a binary thing, there is no retroactivity. As soon as someone is created, they exist and there is responsibility for what happens to them. If bad things happen to them, which is quite inevitable to varying degrees, those who decided to create people are responsible for those harms even if they didn’t intend to harm, but rather the opposite. You can definitely love someone and hurt them.
Once we think that people have a right that others refrain from actions that involve significant and unjustified harm to them, we hold responsible the creators of such situations, even if the creators had no intention to harm, even if this harm was not certain or its chances to occur are low, even if there is no other way to create people. This is derived from the right of the crated people, not the intentions of the creators.
Others may object to the term harm because the parents do not intend to harm and at least in most cases they are not the ones doing the harm.
But you can hurt others in many ways without meaning to. When people are aware of the expected dangers for their children if they create them and decide to create them anyway, that makes them responsible for these harms, at least to a certain extent, even if they did not intend for their children to be harmed, and even made efforts to prevent them from being harmed. Lack of intention or desire that someone will be harmed in a case where someone knowingly puts someone else in a vulnerable state in the face of a host of potential dangers, does not exempt from guilt and responsibility for the harm if such harm occurs.
Clearly, unintentional harm is less grave than harm with malicious intent, but it’s sufficient that people are aware that at least some harm that will be caused to their children is inevitable, and that more is lurking around every corner, for us to talk in terms of parents harming their children. No one forced them to create their children, they did so despite the inevitable risks and harms, and thus they harmed their children. For example, everyone knows that everyone dies in the end. Although parents do not want their children to die, be afraid of dying, or be afraid that their parents or others they love will die, they still decided to produce someone who will inevitably die someday, who will be aware that someday s/he will die and therefore will suffer death anxiety at some level for most of life, and who will be afraid that others around her/him will die, for most of her/his life. And this is true for any other foreseeable or definite harm. If I know that something I want to do puts someone at risk or will surely hurt someone, and I decide to do it anyway, even if hurting that someone is completely against my will, my conscious decision to do so is definitely harming that someone.
Specific people are not responsible for the vast majority of the dangers in the world, but they are specifically responsible for their decision to create someone in a world full of dangers. They didn’t choose to create the dangers in the world, but they chose to create someone in a dangerous world. And for that they should definitely be held accountable.
A person is responsible for harm if s/he acts freely and could have foreseen the harm in advance and could have prevented it. All these conditions apply to reproduction.
Many parents usually say that they created their children in order to protect them, but this is of course a misunderstanding of the concept of creating people. You don’t need to protect someone who doesn’t exist because someone who doesn’t exist is in no way exposed to any harm. Before someone is created there is no subject that can be harmed by something. It is existence and existence alone that can harm people, therefore ironically but very tragically, in choosing to create someone who did not exist in any way before, parents expose someone to the harms from which they seek to protect that someone. No one needs protection before they exist. There are no dangers in non-existence. It is the existence that is dangerous, and it was created by the parents. It is the parents who decide to create someone vulnerable in a very dangerous world and then seek to protect that someone. This is not only completely unreasonable on their part, it also makes them responsible for this situation.
Parents are not heroes and are not doing anyone a favor by trying to protect their children, this is their duty. And not because they are the parents of their children, but because they are the ones who created their children and thus exposed them to harms that were not there before.