Short labor, long labor

I have been thinking about the use of length of labor as an outcome of interest in scholarly papers about birth. If you search length of labor on Google Scholar, all 8 relevant hits on the first page assume that shorter is better.*

(Molly wrote a post about this from a birth story or personal perspective - that some women may find fast labors more frightening, and that her very long labor was wonderful for her.)

I'm not sure length of labor makes any more sense as a study outcome in populations, either. Is this really the ideal curve?

sciencey drawing

In a medical birth setting, providers are invested in speeding labor up; many common interventions serve this purpose. Since all of these interventions will not have been withheld in studies, the data is going to be a little warpy (technical term). This is like the data conundrum in looking at average length of gestation. Many women gestate their babies for much shorter than the norm, but few will remain pregnant way longer than the norm because they'll be induced to prevent it. Similarly, many labors will be much shorter than the norm, and few will be much longer than normal. (We can separate out labors/pregnancies that are shorter than normal because of medical interventions, needed or not, and those that are shorter than normal just because that's what that woman's body is doing, pathological or not.)

Why the professional bias toward shorter labors? My guess is because of the relationship between length of labor, failure to progress, and eventual cesarean section. It sounds dumb to say it, but short labors never fail to progress. Long labors do often result in c-sections, but as ever, it's important to think of cesarean as a medical decision, rather than a medical outcome. In some long labors, a c-section is really called for. In other cases, it's not - more time is what's needed.

Using 'length of labor' as a measurable outcome in published studies fails to distinguish these cases (and ignores overly short/precipitous labors) by looking at average length of labor and assuming that shorter means better. Women's experiences contradict this blanket statement; it seems like common sense does too.

Does anyone know of other writing or thinking on this topic?

PS. If you enjoy reading about babies and epidemiology and curves and stuff, try this out. It will either blow your mind or put you to sleep.

*(It took me like 30 seconds to realize that "Optimal length of labor contracts" was not a relevant hit. I'm thinking I've never heard the use of 'labor contracts' to refer to contractions ... then realize it's from an economics journal. Oh.)