Ignore the hype about epidurals — we still don’t know what causes postpartum depression

CBC News | By Patricia Tomasi 11/22/2016

An unpublished study suggests that epidurals “may” help reduce PPD in “some” women

It’s time to set the record straight: labour pain and epidurals do not cause or prevent postpartum depression (PPD).

No one knows what causes postpartum depression. And no one knows what can prevent it. So please, stop misleading women into thinking that getting an epidural will ward it off.
It won’t. Or it might. We don’t know. And we won’t know until credible, overwhelming medical evidence tells us otherwise. But it hasn’t yet.

An unpublished study

The recent confusion over labour pain, epidurals and postpartum depression stems from news reports and blog posts about a preliminary, unpublished study suggesting that epidurals “may” help reduce PPD in “some” women. The news came by way of a press release from the American Society of Anesthesiologists (ASA), which hosted a presentation by one of the study’s authors, Dr. Grace Lim, during their annual general meeting last month.

The press release got substantial mainstream pick-up, likely due to the ongoing debate about medicated versus natural childbirth. And with an endorsement by the ASA on a study claiming epidurals to be the panacea of postpartum depression, how could the media resist?

Indeed, the coverage was swift and sensational:

“This new study suggests pregnant women really, really should just get an epidural,” wrote the headline writers at Yahoo. The website for Time magazine went with: “How an epidural may lower postpartum depression risk.”

“Getting an epidural can prevent postpartum depression” explained POPSUGAR.

It all sounded so exciting. But as most issues involving mental health, it’s not really that simple.

Postpartum depression vs. baby blues

Rates of PPD vary, but the consensus among mental health professionals is that affects anywhere from six to 13 per cent of mothers, and can include feelings of sadness and anxiety that persist beyond a two week period, up to the first year postpartum. The baby blues — the symptoms of which are less severe and shorter lasting than postpartum depression — occurs in about 60 to 80 per cent of new mothers and can last for weeks following childbirth. We still don’t know what causes PPD, or what women can do to prevent it.

For their study, Dr. Lim and her colleagues examined the medical records of 201 women who received labour epidural analgesia to find that at six weeks postpartum, these women scored low on a scale used to diagnose PPD (Edinburgh Postpartum Depression Scale). From that data, the authors then concluded that improvement in pain during labour under epidural analgesia is “a significant predictor in the development of postpartum depression symptoms.”

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Postpartum depression can develop at any time during the first year after birth.

The problem with that conclusion is that postpartum depression can develop at any time during the first year after birth: my own symptoms didn’t begin to surface until three months postpartum. Yet in the preliminary study touted by the ASA, symptoms were not evaluated past six weeks postpartum.

What’s more, the women evaluated in the epidural study were not assessed for post-traumatic stress disorder (PTSD), even though, according to the Birth Trauma Association, PTSD following a traumatic childbirth experience is often misdiagnosed as PPD. On its website, the Association notes that while some of the symptoms are the same, the two illness “are distinct and need to be treated individually.”

The study was also limited in that it only examined epidurals as the only method of labour pain relief, though many women choose alternate or additional means of dealing with pain during labour (hypnobirthing, for example). And to draw any conclusions from the study at all is to assume that labour pain actually causes postpartum depression, which has yet to be proven; the most this study demonstrates is a correlation, not causation — and a weak correlation, at that.

Author’s reservations

When contacted by phone, Dr. Lim conceded that her study is very preliminary and “subject to many limitations inherent in searching through medical records for information.”

“I think I was initially surprised by the media pick-up,” said Dr. Lim. “When I was talking with them (ASA) about it, we wanted to make it clear how preliminary the results were and how much more research and work is needed to try and investigate this area.”

It’s curious, then, that the ASA would issue a press release about a study that hadn’t been peer reviewed, especially when one of its authors expressed such reservations.

Perhaps the ASA jumped at the chance to send out a “good news” story, what with recent reports of epidurals increasing the rate of c-sections and the amount of time a mother labours.

But the science needs to be credible, lest the public be duped into believing claims that haven’t yet been properly substantiated. Without a doubt, the notion that epidurals prevent postpartum depression is one of them.

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