The patriarchy. I mean there are lot of reasons why, but fundamentally, it supports the patriarchy. Old, white, rich men having control over women, children, people in relative poverty and POC and not allowing other groups to have meaningful power, thus perpetuating the patriarchy. Women are becoming a bit too powerful for the comfort of the patriarchy, and need putting back in their place.
Women who can choose to have children later in life, or not at all, are likely to better educated, more skilled, have better employment prospects, more wealthy and more politically active. In short, they do not actually need men, and are therefore significantly less oppressed by the patriarchy.
If it were really about neonatal rights, they could be putting money into family planning, sex education, contraception availability, adoption and fostering support, and counselling women. And forcing men to pay child support and supporting fathers to step up and care for their children, and stepping in as the state to help women when they don’t or can’t. Even promoting the benefits of temporary vasectomies for young adult men until they are ready for children. But they aren’t. They are simply forcing more women to bear the astronomical burden of an unwanted child. Not men, just women.