Evidence in medicine: Length of pregnancy

Several doctors, midwives, and pediatricians have said to me recently that they practice "evidence-based medicine," unlike many of their colleagues.

Evidence-based medicine is, presumably, about practicing using interventions and techniques which have been supported by empirical, clinic-based evidence—and avoiding techniques which are untested or have failed empirical tests. As one advocate explains,

The practice of evidence based medicine means integrating individual clinical expertise with the best available external clinical expertise from systematic research....By best available external clinical evidence we mean clinically relevant research, often from the basic sciences of medicine, but especially from patient centred clinical research into the accuracy and precision of diagnostic tests (including the clinical examination), the power of prognostic markers, and the efficacy and safety of therapeutic, rehabilitative, and preventive regimens (D.L. Sackett et al., British Medical Journal, 1996).

What alternatives are there to basing medical practice on evidence?
Theory-based medicine?
Ideology-based medicine?
Tradition-based medicine?
Sentiment-based medicine?


In the face of the obvious, there is indeed much of standard medical practice that remains empirically unsupported. To take an example, the standard formula for the expected length of pregnancy is calculated according to Naegele's Rule, which places the due date at 40 weeks from the start of the last menstrual period. This guideline was calculated in 1838 by German physician Franz Carl Naegele based on the belief that a term pregnancy ought to last exactly 10 lunar cycles (a nice, round number). It was not based on empirical data.

Indeed, empirical studies have shown that length of pregnancy is influenced by previous number of births, age, race, and other factors. So, for instance, the duration of pregnancy for white women with no previous births averages 7 days longer than Naegele's rule predicts (Mittendorf, American Journal of Obstetrics and Gynecology, 1990 and 1993).

Where is the harm in this? Standard practice for many obstetricians is to recommend labor induction—which increases risks to mother and baby—in the 41st week of pregnancy. This is the point at which, at least for first time mothers, only half would be expected to go into labor naturally. The most current figures I could find (from 2002) show that induction rates exceeded 50% for some hospitals, and anecdotal evidence is that they are now even higher.

FEMMSS call for papers

Feminist Epistemologies, Methodologies, Metaphysics, and Science Studies (FEMMSS) Conference

Theme: "Knowledge that Matters"

February 8-10, 2007
Arizona State University, Tempe, Arizona

Call for abstracts for individual papers or panels

Questions of difference, democracy and justice have been at the forefront of feminist discussions about what knowledge matters for social justice. How knowledge is produced, distributed, and taken up is intricately connected to questions of equality, ethics, sustainability, power, identity, voice, and social change. Activism and advocacy are so central to feminist knowledge that Lorraine Code argues “without advocacy and the negotiations it commonly enlists knowledge is not possible, in a strong sense, across diverse communities and socio-ecological situations.”

We seek feminist papers on the culture, structure, discourses and practices of science; about the vexed relationship between identity, experience and knowledge; and about the troubles of translating knowledge into action and practice. We will bring together an interdisciplinary group of feminist scholars who pursue knowledge questions in the interstices of epistemology, methodology, metaphysics, ontology, and science studies. Themes for the conference include:

Can science serve social justice in ways that expand democratic participation and empowerment? Or have attempts to expand participation foundered given the prevailing power structures within which they have taken place?
How do formations of class, gender, race and ethnicity, sexuality, and differences unspecified determine the social structure of technology and science, the questions considered relevant within it, and the outcomes that emerge from it?
What is the convergence between how we think about social reproduction and the gendered/racialized division of labor, and our understanding of why we have the science (and scientists) we have?
How can diverse social groups meaningfully participate in research priority setting and have a say in guiding research trajectories?
How can we do science including human science after the feminist critique of science?
Are there democratic models of epistemology and what do they share?
What are some of the promising new methodologies that can help us to understand the way science and technology construct and govern subjects?
How can we best create robust links between feminist epistemologies/science studies and activism?
What are some strategies for bringing policy concerns to the work of FEMMSS and the work of FEMMSS to policy-makers?

Please submit a 500 word abstract of your paper or panel proposal by September 15, 2006
at the FEMMSS/2 link at the Women and Gender Website at ASU at www.asu.edu/clas/womens_studies.

FEMMSS website is here.