When I was pregnant, I obediently took the iron pills and prenatal vitamins prescribed by my obstetrician. And I prescribed them for every pregnant patient I took care of as a family physician. I never questioned the practice. It seemed intuitively obvious that it was a good thing; we know pregnancy makes extra nutritional demands and depletes iron stores. It never occurred to me to question what I had been taught, because it seemed perfectly logical. I did question other things I was taught that didn’t seem so logical. In my internship, we were ordered to do episiotomies on every patient (the rationale was that it made birth less traumatic for the baby and prevented uncontrolled perineal tearing in the mother). I was severely chastised for omitting an episiotomy on a patient who begged me not to do one. She had had several babies and was stretchy enough to deliver easily without an episiotomy. In this case, my common-sense clinical judgment was vindicated by further research in the years after my internship; new evidence showed that routine episiotomies were of no benefit, practice changed in response to the new evidence, and episiotomies are no longer done routinely.
That was a long time ago. I have long since learned that even the most reasonable assumptions can be wrong. I happened to be right about episiotomies, but I might just as well have been wrong; and the only way to know whether a belief is true is to test it in controlled scientific trials. As Will Rogers said, “It isn’t what we don’t know that gives us trouble, it’s what we know that ain’t so.” It turns out that routine multivitamin and iron supplementation is not supported by any convincing evidence from scientific studies. And practice is changing. Recently, when one woman asked her OB what she should do about prenatal vitamins he pulled his wastebasket out from under his desk and said “put them there.” (more…)