The US fertility rate has yet again hit a record low this year, continuing a decline that began in 2007. While some conservatives frame this as a matter of "selfishness over sacrifice" — suggesting women are choosing careers over families — the data tells a more complicated story. Birth rates are falling across the board , including among teenagers and women without college degrees. And of course, while the advent of birth control and shifting social priorities all arguably affect the declining birth rate to some degree, for many, the issue is far more practical: Raising children has become prohibitively expensive. With the rising costs of childcare, housing, food, and healthcare, having a family can feel less like a given and more like a luxury. And for those without a partner or in a dual-income household, it can start to feel out of reach altogether. For Bernie Sinclaire, a 38-year-old mother of two and teacher at an all-girls school in the Bronx, that reality led her to try something different.…