The Semmelweis Reflex: Rejecting Results that Contradict Strong-Held Beliefs

The semmelweis Reflex is a reflex-like rejection of new knowledge because it contradicts entrenched norms, beliefs, or paradigms.

The following slides provide a summary of the amazing story of Semmelweis.

Semmelweis Reflex (PDF)



The details below are from the book Childbed Fever: A Scientific Biography of Ignaz Semmelweis, Leadership and Self-Deception, the Encyclopedia Britannica, , and Wikipedia.


Semmelweis was a European doctor, an obstetrician, in the mid 1800s.He worked at Vienna’s General Hospital, an important research hospital.The mortality rate in the ward where he practiced was one in 10 – one in every ten women giving birth there died!The reputation of Vienna General was so bad that women preferred to give birth on the street and then went to the hospital.In the book Childbed Fever, they estimated that 2,000 women died each year from childbed fever in Vienna alone, and that in nineteenth-century Europe, childbed fever killed more than a million women.

The collection of symptoms associated with these deaths was known as “childbed fever” or Puerperal fever.More than half the women who contracted the disease died within days.Patients begged to be moved to a second section of the maternity ward where the mortality rate was one in fifty – still horrific, but far better than one-in-ten in Semmelweis’s section.

Semmelweis became obsessed with the problem.He tried to control for all factors, including birthing positions, ventilation, diet, and even the way laundry was done.The one obvious difference between the sections was that Semmelweis’s section was attended by doctors, while the other section was attended by midwives.

After a four-month leave to visit another hospital, he discovered that the death rate had fallen significantly in his section of the ward in his absence.This, coupled with the death of his friend Jakob Kolletschka from an infection led to the breakthrough.Jakob’ contracted an infection after his finger was accidentally punctured with a knife while performing a postmortem examination and his autopsy showed a pathological situation similar to that of the women who were dying from childbed fever. Semmelweis proposed a connection between cadaveric contamination and childbed fever.

Yes, cadavers.Semmelweis spent far more time doing research on cadavers than other doctors.

Vienna General was a teaching and research hospital and many doctors split their time between research on cadavers and treatment of live patients.The doctors in his section performed autopsies each morning on women who had died the previous day, but the midwives were not required or allowed to perform such autopsies.They hadn’t seen any problem with that practice because there was as yet no understanding of germs.

Semmelweis concluded that ‘particles’ from cadavers and other diseased patients were being transmitted to healthy patients on the hands of the physicians.He experimented with various cleansing agents and instituted a policy requiring physicians to wash their hands thoroughly in a chlorine and lime solution before examining any patient.The death rate fell to one in a hundred!

After the initial success, where rates dropped, a new group of students was admitted and the students neglected the washings.Mortality rate increased and Semmelweis instituted stricter controls: the names of students were publicly displayed and assigned to each woman in labor, making it obvious who neglected the washings.Once again, the mortality rate fell (Childbed Fever, p. 53)

What is surprising about this story isn’t the discovery through attempts to control for factors, which led to the unthinkable conclusion (at the time) that there was something invisible that was transferred by the doctors.What is really shocking is how long it took the community of doctors to accept the results.

According to Childbed Fever: A Scientific Biography of Ignaz Semmelweis (p. 69) an 1856 publication in a prominent Viennese medical periodical, Viennese Medical Weekly, by Jozsef Fleischer, a student of Semmelweis, showed success of chlorine washings.However, the editor for the periodical wrote at the end of the report “We believe that this chlorine-washing theory has long outlived its usefulness.The experiences and statistical results of most maternity institutions protest against the views presented above.It is time we are no longer to be deceived by this theory.”

Vienna continued to ignore his recommendations.In 1861, he published a book, but the community rejected his doctrine.In 1865 he suffered a nervous breakdown and was taken to a mental hospital, where he was beaten by asylum personnel and died.It took another 14 years for the discovery to be accepted, after Louis Pasteur, in 1879, showed the presence of Streptococcus in the blood of women with child fever. Semmelweis is now recognized as a pioneer of antiseptic policy.

More is available at Wikipedia’s Contemporary reaction to Ignaz Semmelweis.

A 2005 article called Simpson, Semmelweis, and Transformational Change by Grant etal. in Obstetrics and Gynecology claims that despite 150 years of evidence, recent research shows that hand-hygiene practices by healthcare workers remain unacceptably low.Inadequate hand washing is one of the prime contributors to the 2 million health-care-associated infections and 90,000 related deaths annually in the United States.

The Semmelweis Reflex is reflex-like rejection of new knowledge because it contradicts entrenched norms, beliefs or paradigms.