Could Labor Epidurals Increase Risk of Autism?

by | Nov 19, 2020 | Coping with Labor Pain

A new study links epidurals for labor pain with Autism Spectrum Disorder (ASD) diagnosis in the child.

Should you be worried?

How believable is this finding?
How concerned should you be?
How might this influence your decision to have or not have an epidural?

Let’s answer those questions.

How Believable Is This Finding?

The study was well-designed and conducted. Investigators used a large U.S. database in which all children were evaluated for ASD at 18 to 24 months of age, and they took into account a long list of other factors that could explain the association. Even after doing that, the babies of mothers who had labor epidurals were nearly 40% more likely to be diagnosed with ASD, although in absolute numbers, the difference was small: 19 per 1000 children in the epidural group versus 13 per 1000 in the non-epidural group, or a difference of 6 more per 1000. Furthermore, the odds rose with epidural duration, which supports that epidurals are responsible because it suggests that the more anesthetic that gets into the baby’s circulation, the greater the likelihood of an effect. Finally, they offered an explanation for the connection: epidural anesthetic agents have been shown to have harmful neurologic effects. (Scroll down to “Taking a Deeper Dive” if you’re interested in more details.)

So, given this,

How Concerned Should You Be?

To begin with, “association” isn’t “causation,” and, in fact, a study design of this type—an analysis of information from a database—can’t show causation. Causality in this case is more plausible than, say, noticing that your team wins more often when you wear your lucky shirt than when you don’t, but it’s in the same category.

For another, I would advise skepticism when a brief exposure is credited with so profound an effect. Even if epidural anesthetics have neurotoxic properties, living tissues are resilient and can heal. Also, many other factors could have played a role in the intervening months before diagnosis. The association may be due merely to chance like observing—and I’m making this up as an example—that more babies born in the spring develop asthma in childhood. Maybe there’s a connection; maybe not.

Epidural use may also be a marker for the true cause. For example, suppose a study found that women who drank three cups of coffee or more per day were more likely to have low birthweight babies. But perhaps women who drink more coffee are also more likely to be heavy smokers, and heavy smoking was the real culprit.

Finally, while roughly a 40% increase in risk sounds alarming, as I noted, the actual difference: 6 per 1000 is quite small. What is more, this is the risk in the population overall, which means including women with other, more potent risk factors. If you don’t have those risk factors, your individual risk would be correspondingly reduced.

The Take-Away: How Might This Influence Your Decision Making About an Epidural?

All the above being said, this was a well-conducted study that accounted for other possible explanations for its findings and offered a plausible explanation of why epidurals might be responsible. If we assume the connection between epidurals and ASD is real, what might you take away from this study?

If you decide to plan to avoid or delay an epidural, be sure to take a childbirth preparation class that emphasizes non-drug techniques and comfort measures and consider hiring a doula. You and your partner will want to be well prepared for you to cope with labor without one.

Tip: Childbirth preparation classes and doula support are both available virtually.

Taking a Deeper Dive

To evaluate the effect of epidural analgesia in labor, study investigators used a U.S. database in which all children were screened for ASD at 18-24 months. Among the 147,895 children, 109,719 of them were born to women who had labor epidurals. Overall, 2524 children (17 per 1000) were diagnosed with ASD, 2039 (19 per 1000) in the epidural group and 485 (13 per 1000) in the non-epidural group, or a difference of 6 more per 1000. After adjusting for a long list of factors that could account for a difference in ASD rates, this calculated to a 37% increase in likelihood of ASD.

Likelihood of ASD also increased with increasing duration of the epidural. Finding a dose-dependent response strengthens the case that labor epidurals are responsible.

The investigators looked for other possible explanations for their findings, but the conclusion was unchanged when analysis was limited to one child per family (ASD runs in families), excluded preterm births, or excluded children with inborn abnormalities. Maternal fever in labor is a side-effect of epidurals that might explain the association especially since its likelihood, too, increases with epidural duration, but while more women with epidurals ran fevers in labor (12% vs. 1%), maternal fever didn’t explain the excess cases of ASD either. Longer labor might also be an explanation, but the investigators cite studies failing to find an association between labor length and ASD.

Finally, the investigators offer a possible explanation for the link: they observe that epidural anesthetic agents enter maternal circulation and can cross the placenta, and they have been shown to have neurotoxic effects.

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