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SPH Study: Increased Risk of Birth Defects from Opioid Use

Surge in use during pregnancy stirs concerns

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Although potential risks to a developing fetus remain largely unknown, doctors are prescribing opioid painkillers to pregnant women in startling numbers. A recent study published in the journal Obstetrics & Gynecology shows a staggering 23 percent of 1.1 million pregnant women enrolled in Medicaid nationally filled an opioid, or narcotic, prescription in 2007—up from 18.5 percent in 2000. That is the largest usage rate of opioid prescriptions among pregnant women to date.

An earlier study in the journal Anesthesiology found 14 percent of privately insured women received opioid painkillers at least once during pregnancy.

In both studies, the most commonly prescribed opioids were codeine and hydrocodone; oxycodone was among the top four. The drugs were usually dispensed for a week or less, although a small fraction of women were prescribed them for longer. Doctors may prescribe the narcotics for discomfort in pregnancy caused by posture changes, weight gain, and pelvic floor dysfunction, or more serious ailments. In the two recent studies, opioids were most often prescribed for back pain or abdominal pain.

These findings worry Martha M. Werler (SPH’89), a School of Public Health professor of epidemiology and a senior epidemiologist at the Slone Epidemiology Center, whose research has shown an association between first-trimester use of opioids and neural tube defects, which are malformations of the brain or spine, such as spina bifida. Neural tube defects are among the most common birth defects, occurring in more than 300,000 births worldwide each year.

Martha Werler, professor of epidemiology, chair of epidemiology, Boston University School of Public Health, SPH

Research by Martha Werler, an SPH professor and chair of epidemiology, finds that women who had a child with neural tube defects were twice as likely to have used opioids early in their pregnancies as mothers whose children were born healthy. Photo courtesy of the School of Public Health

A 2013 study by Werler found mothers who had babies with neural tube defects reported more use of opioids early in their pregnancies (3.9 percent) than mothers of children without such congenital defects (1.6 percent).

“Our study suggests that women of childbearing age—not just those who are pregnant—should refrain from opioid use because neural tube defects develop in the first weeks of gestation, when pregnancy may not be recognized,” says Werler, SPH’s incoming chair of epidemiology. “About half of pregnancies are not planned, so that’s a big chunk of women who may not be thinking about possible risks associated with their behavior.”

The Centers for Disease Control and Prevention (CDC) recently launched a website called Treating for Two, which offers guidance to clinicians and expectant mothers on medication use in pregnancy. It notes that medication use during pregnancy in general has surged: 9 out of 10 women now take some medication during pregnancy.

BU Today spoke to Werler about the trend of prescribing opioids for pregnant women and the possible implications.

BU Today: So you are concerned about the studies showing doctors prescribing opioids to pregnant women in significant numbers?

Werler: Yes. Even the proportion in 2000 seems high to me, and the increase makes it that much more concerning.

What do you think is driving the trend?

I can think of no condition in pregnancy that has increased in parallel, for which opioids would be prescribed. This leads me to wonder about overprescribing.

How does your own study play into the concerns about opioid use?

Our study was the third to observe a positive association between maternal use of opioids and neural tube defects. In our study, the doubling in neural tube defect risk for opioid exposure was not explained by socioeconomic factors or other behavioral factors, such as cigarette smoking, illicit drug use, and low folic acid intake.

Do we know how opioid use might affect prenatal development?

Neural tube defects result from a failure of the developing brain or spinal column to fuse properly in very early pregnancy. Some neural tube defects cause death, while others can impair cognitive abilities, mobility, and kidney function.

It is not known how opioid use might affect the developing neural tube. We can speculate based on animal studies, which show opioids affecting the fetus at the molecular, cellular, and tissue levels—but the bottom line is that we just don’t know. For that matter, we don’t know the exact mechanism by which folic acid protects against neural tube defects, either. Unfortunately, there is a gap between epidemiologic studies and basic science in studies of birth defects.

Are there good alternatives to opioids for pregnant women who need pain relief?

Acetaminophen, aspirin, ibuprofen, and naproxen are the most commonly taken pain remedies. These medications are not addictive—but their ability to reduce pain may not be sufficient for the most severe situations. The effects of these nonaddictive pain medications on neural tube development have not been thoroughly studied.

As always, the clinician and patient must make the best choice for the circumstances, taking the health of the mother and the fetus into account.

Lisa Chedekel can be reached at chedekel@bu.edu.

4 Comments

4 Comments on SPH Study: Increased Risk of Birth Defects from Opioid Use

  • Richard Long, MD on 07.15.2014 at 6:51 am

    Aspirin, ibuprofen and naproxen are generally contraindicated in pregnancy because of their anti-platelet effects and risk for placental abruption. Acetaminophen has recently been tied to higher risk of ADHD in pregnancy exposed children. There are no perfect options. I suspect in this retrospective analysis of opioid exposure in pregnancy that mothers who use narcotic pain medications especially early in pregnancy are also exposed at a higher rate to other medications in pregnancy as well.

    • Marie Durand on 07.16.2014 at 9:14 pm

      There is a second study in which acetaminophen use during pregnancy has been shown to increase the risk of adverse neurodevelopmental outcomes. This study found a 70% increased risk of behavioral and motor problems and double the risk of communication problems in 3 year olds from prolonged use. http://bit.ly/1eG2K9u

  • Diana R Wallace, M.D. on 07.15.2014 at 8:46 am

    (SAR ’87, SAR ’89)
    One problem is that pregnant women can only take acetaminophen. NSAIDs early in pregnancy are okay, but can cause problems later, so we generally tell patients to avoid them throughout. Fioricet is a possibility for headaches (acetaminophen-caffeine-butalbital), but if the patient has other types of pain, it’s very difficult to manage since our arsenal is so restricted. We generally avoid narcotic-containing meds, but sometimes it can’t be helped.

  • inlegitimatepain on 09.10.2014 at 6:40 pm

    ok Boston Hospital. I know you are an excellent and very intelligent facility but please stop scaring people with this nonsense. All sorts of things cause damage to the fetus. We know this. It is not just Opiates that may cause problems during pregnancy. Many things….even something as simple as diet or smoking may cause a problem Please stop spreading more fear. Chronic pain patients are suffering so needlessly now. Please stop frightening people with your bias and do more research. Maybe you will find a way to help people who are already adults whose mothers did care for their bodies during pregnancy, even when it was difficult, as mine was because of 2 hip replacements. I had a healthy baby. I was able to stop all medications during pregnancy for the sake of my child. I’m sure if you forced too many vitamins on a pregnant woman then she may have a bad pregnancy outcome. It happens. Please help people who are already suffering when they could be helped by opiates. People don’t need these scare tactics that don’t cover all the bases in the “real” world anymore. People need help.

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