The main reason that birthrates are low is simple: People today want smaller families than people did in the past. That’s true in different cultures and economies around the world. It’s what both women and men report in surveys. Humanity is building a better, freer world with more opportunities for everyone, especially for women. That progress deserves everyone’s greatest celebration — and everyone’s continued efforts. That progress also means that, for many of us, the desire to build a family can clash with other important goals, including having a career, pursuing projects and maintaining relationships. No society has solved this yet. These tradeoffs bite deep for parents everywhere. For some parents, that means struggle. For others, that means smaller families than they hoped for. And for too many, both.