In 1846, Ignaz Semmelweiss was appointed as an assistant at a Vienna teaching hospital with two maternity clinics run by doctors and midwives in training. The clinic often took in poor women and sex workers who had become pregnant. The doctors’ ward was notorious for the deaths of mothers and a high infant mortality rate, while the midwives performed consistently better on ensuring safe births. Semmelweiss took note of the discrepancy in mortality rates between wards, and tested variable practices in birthing with the scientific method–no luck. After a physician received a cut from a blade used in an autopsy on one of the pregnant women, and died with the same symptoms she had, Semmelweiss knew he was onto something. Revelation came when he implemented a handwashing regime for his colleagues between the morning autopsies and afternoon births they facilitated.

After hand washing was instituted, the mortality rate in the doctor’s ward declined 90%. A year following this discovery, the mortality rate dropped down to zero for at least two months.

The handwashing regime implemented with a chlorine rinse improved the quality of care given to mothers, chemist Louis Pasteur wouldn’t have discovered germ theory until over 20 years later. What the doctor had was more than 18 months of statistical data showing his hand washing approach worked and that such practices could save the lives of thousands of expectant mothers. He had the truth—but it wasn’t enough.