I was the second to get pregnant. My sister-in-law went first; two years later, I had my son—and then two more kids, in relatively rapid succession. The two of us had this joke—I’m sure you’ve heard it—that with the first kid you sterilize the bottle if you drop it on the floor, with the second you put the nipple in your mouth to clean it off, and with the third, you wipe it on your pants. Just writing that makes me cringe. But back then, we didn’t really think much about germs—or toxic chemicals in cleaning products.