The establishment's failure to recognize his findings earlier led to the tragic and unnecessary death of thousands of young mothers, but he was ultimately vindicated. A typical case where scientific progress was slowed down by the professionals apparatus. In Vienna, Semmelweis was considered a foreigner and later in his career moved back to neighboring Hungary.
Semmelweis was responsible for two birthing pavilions, and realized that the number of cases of puerperal fever was much larger at one than at the other. In fact, in one pavilion, very few women survived childbirth, while in the other, most women survived. This was a known fact and the women rather gave birth to their children on the street than being brought into the death-pavilion. He pondered the situation, and found that the only difference was that the fatal pavilion was staffed by student doctors, while the benign pavilion was staffed by midwives. Both used the same techniques.
After testing a few hypotheses, Semmelweis finally concluded that the difference could only be attributable to the fact that the medical students were handling corpses before attending the women. He found that the number of cases was drastically reduced if the doctors washed their hands carefully before dealing with a pregnant woman. The germ theory of disease had not yet been developed at the time. Thus, Semmelweiss concluded that some unknown "cadaveric material" caused childbed fever.
He lectured publicly about his results in 1850, but the reception by the medical community was cold, if not hostile. His observations went against the current scientific opinion of the time, which blamed diseases (among other quite odd causes) on an imbalance of the basical "humours" in the body. His superior at the Hospital tried to suppress his ideas for egoistic reasons. It was also argued that even if his findings were correct, washing one's hands each time before treating a pregnant woman, as Semmelweis advised, would be too much work. Nor were doctors eager to admit that they had caused so many deaths; indeed, they tended to claim that their profession was one divinely blessed and thus their hands could not be dirty. Semmelweis spent 14 years developing his ideas and lobbying for their acceptance, culminating in a book he wrote in 1861, after introducing and verifying the practical success of his methods. The book received poor reviews, and he responded with polemic.
It was a last cynical irony that he was brought down by an infection, that he lifelong and indeed bitterly fought against.