A news release from the American Society of Anesthesiologists highlights the results of a preliminary study on the effect epidurals might have on post-partum depression.
According to the release, “some” of 201 women who choose epidural pain relief during the birth of their child saw a decreased risk of developing postpartum depression, or PPD. Specifically, those who scored lower on a pain improvement scale showed a lower likelihood of developing PPD. The release notes two risk factors were accounted for in detecting this association — depression and tissue trauma caused by birth — and indirectly hedges on how something else may be responsible for the perceived effect
However, that’s where the utility of this release ends and its problems begin. How many women saw a benefit? What about the strength of the effect? Were all of the biggest confounding factors accounted for, like social support and economic status? Why weren’t women who chose natural births not used as controls? And is natural birth really so risky and traumatic, as this release implies?
Those are just a few of the important questions that this release (and even the not-yet peer-reviewed study it’s based on) fail to answer or simply address. The tone of the news release and the abstract (both by the American Society of Anesthesiologists) suggests that epidural anesthesia is helpful in preventing postpartum depression, but that assertion remains far from proven. A number of health journalists have picked up this news release and some provided important background details and caveats not found in the American Society of Anesthesiologists release. This article in Cosmopolitan magazine — despite an unfortunate subheadline touting “amazing superpowers” — is a good example. It acknowledges other research suggesting that “…it’s not just the degree of pain, but the amount of support a woman receives during childbirth that can influence whether she’s traumatized by the whole experience and develops depressive symptoms because of it.”
PPD is a very common outcome of birth, affecting roughly one in seven mothers, according to the American Psychological Association. It’s more severe than the normal “baby blues,” caused by hormonal changes following birth, and rarely goes away on its own — it’s a serious disorder that can appear weeks or months after birth and often requires expert care to help resolve.
If a simple and common medical intervention during birth can reduce the risk of PPD, it could benefit millions of women all over the world. That is, if the effect is shown to be causal and significant.
The cost of a birth with an epidural isn’t mentioned. While it depends on the insurance carrier — some pass all or part of the costs of anesthesiology during birth onto consumers — the average epidural in the US adds about $1,200 to a birth bill, with some anesthesiologist practices charging more than $2,700 per epidural.
There are no hard numbers in this release, and that’s a big shortcoming. Journalists and other readers are left imagining just how strong or weak this association is, and what percentage of women might benefit — or not. The best we get is “some women” of 201 who chose to receive an epidural are less likely to experience postpartum depression.
To its credit, the release added some cautionary language regarding the study’s findings:
“Although we found an association between women who experience less pain during labor and lower risk for postpartum depression, we do not know if effective pain control with epidural analgesia will assure avoidance of the condition,” said Dr. Lim. “Postpartum depression can develop from a number of things including hormonal changes, psychological adjustment to motherhood, social support, and a history of psychiatric disorders.”
We’re not told about any of the risks of epidurals.Those risks include a drop in blood pressure (which can complicate an otherwise normal pregnancy), severe headache (in less than 1% of women), slowing of labor due to lying on one side for too long (unless a “walking” epidural is used, though the procedure is rare), shivering, backache, ringing of the ears, nausea, trouble urinating, and the increased likelihood of interventions like forceps and cesarean section (since it can be harder to push). Epidurals also require a catheter to drain urine, which significantly increase the risk of urinary tract infections.
Correlation is not causation, and this release doesn’t go far enough to explain this. The release quotes lead researcher Dr. Grace Lim, who is the director of obstetric anesthesiology at Magee Women’s Hospital of the University of Pittsburgh Medical Center, as saying “We found that certain women who experience good pain relief from epidural analgesia are less likely to exhibit depressive symptoms in the postpartum period.” However, it also stands to reason that some women — whether or not they have an epidural or go on to develop post-partum depression — simply experience less pain.
The release does include a brief caveat regarding the association between epidurals and post-partum depression: “…we do not know if effective pain control with epidural analgesia will assure avoidance of the condition.” And, helpfully, it calls the research “early” and “preliminary.”
The release states the study controlled for two major confounding factors: “pre-existing depression and anxiety” and “post-delivery pain caused by tissue trauma during childbirth.” But that does not mean women who gave birth weren’t already at risk — i.e. they may not have been diagnosed. Also, we aren’t told whether the study accounted for other risk factors known to play significant roles in leading to postpartum depression, including: availability of family and social support; employment status and financial well-being; the mother’s physical health; infant behavior (e.g. colic); whether a pregnancy was planned; and other sources of acute stress. The release mentioned some of these in a quote from a study leader but, again, we aren’t told if the study actually controlled for these conditions.
We found the statement that labor pain “may be psychologically harmful for some women and play a significant role in the development of postpartum depression” a gratuitous assessment, especially given that humans have been bearing children for hundreds of thousands of years without modern analgesics. This statement might scare women away from a perfectly viable alternative, i.e. birth without medicated pain relief.
The release doesn’t mention who funded the study.
The best comparison we get to alternatives is a bit of minor scaremongering. This release really should have brought more to bear on births where women choose to not to use an anesthetic, also called “natural” birthing. It should also be noted that nitrous oxide is increasingly being offered as an alternative in hospitals around the US. That’s worth noting.
Epidurals are so widely available we don’t think the availability needs to be stated.
While technically a novel result, it’s a minor one. We found a 2014 study in Anesthesia & Analgesia that explored the same question, though in a Chinese population and with greater rigor. That study compared women who chose epidurals to those who chose a “natural” birth without epidurals. Interestingly, we found a 2015 commentary that responds to this 2014 study — and it was authored by Lim (the lead author of the new study), who rightfully states that, if epidurals do decrease the risk for postpartum depression, then “it could have tremendous ramifications on the long-term mental well-being of half of the world’s population who are of child-bearing age.” Lim’s letter also called for more research with larger sample sizes to try and replicate the results. But roughly one year later, Lim’s abstract explores the question with no overt controls and a similar sample size.
Nothing jumped out at us here that wasn’t covered in our “disease mongering” criteria.