Sunday, December 20, 2009

A Freakonomics look at Maternal Death during Childbirth

For a laugh, a history lesson, a puzzle that you want to know the answer to, a surprise and then a "ew gross" and "duh" moment with a laugh, read on, my friends. This story is full of interesting and true ridiculous-ness.

This post is a type-up of "The Dangers of Childbirth" from the chapter The Fix is in - And its Cheap and Simple in Super Freakonomics: Global Cooling, Patriotic Prostitutes and Why Suicide Bombers Should Buy Life Insurance by Steven D. Levitt and Stephen J. Dubner published this year.

It is a fact of life that people love to complain, particularly about how terrible the modern day is compared with the past.

They are nearly always wrong. On just about any dimension you can think of - warfare, crime, income, education, transportation, worker safety, health - the twenty-first century is far more hospitable to the average human than any other time .

Consider childbirth. In industrialized nations, the current rate of maternal death during childbirth is 9 women per 100,000 births. Just one hundred years ago, the rate was more than fifty times higher.

One of the gravest threats of childbearing was a condition known as puerperal fever, which was often fatal to both mother and child. During the 1840's some of the best hospitals in Europe - the London General Lying-in Hospital, hte Paris Maternite, the Dresden Maternity Hospital - were plagued by it. Women would arrive at the hospital to deliver a baby and then, shortly thereafter, contract a raging fever and die.

Perhaps the finest hospital at the time was the Allgemeine Krankenhaus, or General Hospital, in Vienna. Between 1841 and 1846, doctors there delivered more than 20,000 babies; nearly 2,000 of the mothers, or 1 of every 10, died. In 1847, the situation worsened: 1 of every 6 mothers died from puerperal fever.

That was the year Ignatz Semmelweis, a young Hungarian-born doctor, became assistant to the director of Vienna General's maternity clinic. Semmelweis was a sensitive man, very much attuned to the  suffering of others, and he was so distraught by the rampant loss of life that he became obsessed with stopping it.

Unlike many sensitive people, Semmelweis was able to put aside emotion and focus on the facts, known and unknown.

The first smart thing he did was acknowledge that doctors really had no idea what caused puerperal fever. They might say they knew, but the exorbitant death rate argued otherwise. A look back at the suspected causes of the fever reveals an array of wild guesses:
  • "Misconduct in the early part of pregnancy, such as tight stays and petticoat bindings, which, together with the weight of the uterus, detain the feces in the intestines, the thin putrid parts of which are taken up into the blood."
  • "An atmosphere, a miasma, or... by milk metastasis, lochial suppression, cosmo-telluric influences, personal predisposition..."
  • Foul air in the delivery wards.
  • The presence of male doctors, which perhaps "wounded the modesty of parturient mothers, leading to the pathological change."
  • "Catching a chill, errors in diet, rising in the labor room too soon after delivery in order to walk back to bed." 
(The rest after the jump)

It is interesting to note that the women were generally held to blame.  This may have had something to do with the fact that all doctors at the time were male. Although nineteenth-century medicine may seem primitive today, doctors were considered nearly godlike in their wisdom and authority. And yet puerperal fever presented a troubling condition: when women delivered babies at home with a midwife, as was still common, they were at least sixty times less likely to die of puerperal fever than if they delivered in a hospital.

How could it be more dangerous to have a baby in a modern hospital with the best-trained doctors than on a lumpy mattress at home with a village midwife?

To solve this puzzle, Semmelweis became a data detective. Gathering statistics on the death rate at his own hospital, he discovered a bizarre pattern. The hospital had two separate wards, one staffed by male doctors and trainees, the other by female midwives and trainees. There was a huge gap between the two wards' death rates:

              DOCTORS WARD                            MIDWIVES WARD
Year      Births   Deaths   Rate                       Births   Deaths    Rate
1841     3,036      237      7.8%                      2,442      86          3.5%
1842     3,287      518      15.8%                    2,659      202        7.6%
1843    3,060       274      9.0%                      2,739      164        6.0%
1844    3,157       260      8.2%                      2,956      68          2.3%
1845    3,492       241      6.9%                      3,241      66          2.0%
1846    4,010       459      11.4%                    3,754      105        2.8%
Total    20,042     1,989                                17,791     691
AVERAGE RATE           9.9%                                                  3.9%

Why on earth was the death rate in the doctors' ward more than twice as high?

Semmelweis wondered if the women patients admitted to the doctors' ward were sicker, weaker, or in some other way compromised.

No, that couldn't be it. Patients were assigned to the wards in alternating twenty-four-hour cycles, depending on the day of the week they arrived. Given the nature of pregnancy, an expectant mother came to the hospital when it was time to have the baby, not on a day that was convenient. This assignment methodology wasn't quite as rigorous as a randomized, controlled trial, but for Semmelweis's purpose it did suggest that the divergent death rates weren't the result of a difference in patient populations.

So perhaps one of the wild guesses listed above was correct: did the very presence of men in such a delicate feminine enterprise somehow kill the mothers?

Semmelweis concluded that this was too improbable. After examining the death rate for newborns in the two wards, he again found that the doctors' ward was far more lethal than the midwives': 7.6 percent versus 3.7 percent. Nor was here any difference in the death rate of male babies versus females. As Semmelweis noted, it was unlikely that newborns would "be offended by having been delivered in the presence of men." So it was unreasonable to suspect that male presence was responsible for the mothers' deaths.

There was also a theory that patients admitted to the doctors' ward, having heard of its high death rate, were "so frightened that they contract the disease." Semmelweis didn't buy this explanation either: "We can assume that many soldiers engaged in murderous battle must also fear death. However, these soldiers do not contract childbed fever."

No, some other factor unique to the doctors' ward had to figure in the fever.

Semmelweis had by now established a few facts:
  • Even the poorest women who delivered their babies on the street and then came to the hospital did not get the fever.
  • Women who were dilated for more than twenty-four hours "almost invariably became ill."
  • Doctors did not contract the disease from the women or newborns, so it was almost certainly not contagious. 
Still, he remained puzzled. "Everything was in question; everything seemed inexplicable; everything was doubtful." he wrote. "Only the large number of deaths was an unquestionable reality."

The answer finally came to him in the wake of a tragedy. An older professor whom Semmelweis admired died quite suddenly after a mishap. He had been leading a student through an uatopsy when the student's knife slipped and cut the professor's finger. The maladies he suffered before dying - bilateral pleurisy, pericarditis, peritonitis, and meningitis - were, Semmelweis observed, "identical to that from which so many hundred maternity patients had also died."

The professor's case held little mystery. He died from "cadaverous particles that were introduced into his vascular system," Semmelweis noted. Were the dying women also getting such particles in their bloodstream?

Of course!

In recent years, Vienna General and other first-rate teaching hospitals had become increasingly devoted to understanding anatomy. The ultimate teaching tool was the autopsy. What better way for a medical student to limn the contours of illness than to thold in his hands the failed organs, to sift for clues in the blood and urine and bile? At Vienna General, every single deceased patient - including the women who died of puerperal fever - was taken directly to the autopsy room.

But doctors and students often went to the maternity ward straight from the autopsy table with, at best, a cursory cleansing of their hands. Although it would be another decade or two before the medical community accepted the germ theory - which established that many diseases are caused by living microorganisms and not animal spirits or stale air or too-tight corsets - Semmelweis understood what was going on. It was the doctors who were responsible for puerperal fever, transferring "cadaverous particles" from the dead bodies to the women giving birth.

This explained why the death rate in the doctors' ward was so much higher than in the midwives' ward. It also explained why women in the doctors' ward died more often than women who gave birth at home or even in the streets, and why women in a longer state of dilation were more susceptible to the fever: the longer a woman lay in that state, the more often her uterus was poked and prodded by a gaggle of doctors and medical students, their hands still dripping with the remnants of their latest autopsy.

"None of us knew," as Semmelweis later lamented, "that we were causing the numerous deaths."

Thanks to him, the plague would finally be halted. He ordered all doctors and students to disinfect their hands in a chlorinated wash after performing autopsies. The death rate in the doctors' maternity ward fell to barely 1 percent. Over the next twelve months, Semmelweis's intervention saved the lives of 300 mothers and 250 babies - and that was just in a single maternity ward in a single hospital.

1 comment:

  1. Brilliant! I bet he didn't have to deal with too much bureaucracy in implementing that change, either...


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