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Baby’s due, but might not have gotten the memo

The views expressed are those of the author and are not necessarily those of Scientific American.

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Cartoon of pregnancy ultrasound
It’s becoming a spectacle of Diana-esque proportions. I can’t quite get my head around the fact that there is a ‘Royal Baby Monitor’ live-streaming the hospital door. Although journalists don’t know when Kate Middleton’s due date is (or was), there’s speculation from People magazine to Perez Hilton that she might have a medical induction to get her labor started – just as Princess Diana did. “There are reports” that she’s eating curries, a traditional attempt to induce labor. Hold that thought: we’ll come back.

This is a royal pregnancy, but it’s a common problem. Induction is becoming more controversial – again. It was very controversial in the early 1970s. In the UK it reportedly peaked at a whopping 56% and settled down to around 25%. It’s rising in the US: over 23% of births in the US were induced in 2010. One concern is that failed inductions are contributing to the increase in cesarean sections, although systematic reviews from 2012 and 2013 are reassuring for now.

[The CDC has since reported that the rate of induction appeared to peak in 2010 and reduced a little in 2011 and 2012. And the data are on cesarean sections are more than reassuring now. More in my update post.]

The introduction of early ultrasound to get an accurate due date helped reduce the problem: fewer babies were born preterm because they were mistakenly thought to be overdue.

The introduction of prostaglandins (hormones) helped too. Prostaglandins work on the cervix as well as contractions, and you could have lower doses because they didn’t need to be taken orally. An induced labor might still be rougher on women, but there haven’t been trials of recent techniques that asked enough women what they think about it.

When pregnancies go into overtime, the risk of a baby dying starts to rise. Healthy babies could keep growing till 43 weeks, so why they are at higher risk sooner than that remains a bit of a mystery – it might be because of the placenta.

The risk of death is fortunately small. One estimate is that 416 women need to have inductions to prevent one baby dying around birth. For many women, that’s enough reason to prefer induction. But many women don’t. In some Australian and Canadian hospitals, the split isn’t all that far from half and half.

The split in obstetricians’ opinions contributes to that. The widely-accepted point to start encouraging induction for being overdue alone is around 42 weeks, but sooner is controversial. That’s partly because of different views about the pivotal randomized trial of routine induction.

There was more than just the difference of inducing routinely versus not inducing routinely going on in that trial. In the group where every woman was induced, they used a different form of induction than the comparison group (who were induced only if there was a specific reason). There’s no way of knowing whether that accounts for the group’s better outcomes, but it leaves room for controversy to thrive.

16th century woodcut of woman and midwife

Woodcut of woman and midwife, in then-popular midwifery book by Jakob Rueff (1500-1588). From the online history archives of the National Library of Medicine.

The methods for medical induction aren’t as much in dispute as they once were, though. Looking at the history of trying to coax and prise out overdue babies since ancient times is not a sentimental trip down memory lane. The balance between stimulating uterine activity and causing rupture took a long time to find.

The cervix has not only been dilated (stretched), but it and the uterus have also been jiggled, pumped full, zapped with galvinism or electrical currents, fingers passed in to sweep the membranes near the cervix, and hooks to break the amniotic sac (bag of waters). Balloons (including condoms), pressurized douches, gadgets that are inserted and then swell, acupuncture, big metal contraptions with major screws, “a sort of miniature metal umbrella” and sea sponges have all been called into service. There was also a “Belt Transistor Pulse Generator” in the ‘70s, which boggles the mind a little. Breasts have been cupped and pumped. You can check out some of these devices here, but some are not for the faint-hearted.

Then there are the substances women have ingested: any number of herbs – sometimes even lethal ones, quinine, borax, ergot of rye, sea-coral and fat from the claws of the polar bear.

It’s not just that some of these things were “not altogether safe” that they were abandoned. Many did not really work.

Which brings us to those curries.

Eating spicy foods belong to a very long list of things you can do yourself that are frequently recommended – and tried. Keep up with the royal baby media frenzy and you’ll probably see them all. Walking and dancing will come up often. Mobility can affect the progress of labor. There don’t seem to be studies showing whether or not moving more can get labor started, though.

Other things on those lists of things you can do yourself aren’t necessarily always harmless. As well as the spicy food, there’s taking a drive down bumpy roads, laxatives, homeopathy, heavy exercise, drinking warm gin and nipple stimulation. Out of that list, nipple stimulation has some signs it might work so it’s still being studied, but there’s either no good research or research showing little if no impact for the others – and that goes for sexual intercourse too.

Some of the things still often recommended, like castor oil, hot baths and enemas, were once standard medical or midwifery interventions. Castor oil is natural, but rather repulsive. It causes nausea in almost everyone and can indeed cause cramps – it just hasn’t been proven to actually start labor.

These misadventures share an underlying problem. People to observe a phenomenon and weave a logical narrative to understand and explain it. Out of that narrative, particular actions or interventions then seem logical too. If A seems to cause B, and C might cause A, then it follows that C will cause B, right? Well, no, not necessarily.

However trials that show no benefit to C may just seem counter-intuitive. And because of course labor will almost always start anyway, it’s easy for people to get the impression that something they did caused it even when it didn’t.

Now I’m going back to peek at how the media circus of the #GreatKateWait is going. Some of it is entertaining. “Push, Kate, push!“ is funny, although as she isn’t in labor, it’s also weird. Pushing on a closed cervix doesn’t end well. If this goes on much longer, how much weirder might it get?


Cartoon of pregnancy etiquette for childbirth adviceMore information on inductions in my September 2014 post – with links to evidence-based consumer information on overdue pregnancy and induction of labor.

The cartoons are my own, under a Creative Commons license.

The thoughts Hilda Bastian expresses here are personal, and do not necessarily reflect the views of the National Institutes of Health or the U.S. Department of Health and Human Services.

Hilda Bastian About the Author: Hilda Bastian likes thinking about bias, uncertainty and how we come to know all sorts of thing. Her day job is making clinical effectiveness research accessible. And she explores the limitless comedic potential of clinical epidemiology at her cartoon blog, Statistically Funny. Follow on Twitter @hildabast.

The views expressed are those of the author and are not necessarily those of Scientific American.

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  1. 1. Fanandala 3:43 am 07/21/2013

    Induced babies are mostly born on Fridays…. because the obstetricians do not want to be called out on the weekend.

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  2. 2. Hilda Bastian in reply to Hilda Bastian 11:01 am 07/21/2013

    Interesting point, Fanandala – although the main reason cesareans etc aren’t usually scheduled for the weekend is because hospitals aren’t as fully staffed on the weekends. Quite a lot of services are affected by that, so it’s just not ideal. Induction doesn’t necessarily mean birth on the same day you were induced: it’s still labor, and it can go on for a long time. I’m not sure what day of the week induced babies are more likely to be born, but it would be a week day. CDC data shows points to earlier in the week for vaginal births:

    Link to this

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