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Pre-Pregnancy Surgery in Mom May Up Risk of NAS in Infants

Babies whose mothers had surgery before pregnancy were more likely to be born with neonatal abstinence syndrome (NAS), researchers found.

In a longitudinal cohort study, the risk ratio for NAS was 1.63 (95% CI 1.49-1.78) when mothers were former surgical patients, relative to otherwise similar mothers, reported Nathalie Auger, MD, of the University of Montreal Hospital Research Centre in Montreal, Canada, and colleagues.

Multiple surgeries prior to pregnancy put women at an even greater risk, as women who underwent three or more pre-pregnancy operations were over 2.3 times as likely to have a baby that developed NAS (95% CI 2.07-2.63), researchers wrote in the Canadian Medical Association Journal.

The opioid epidemic has led to an increase in the number of babies with NAS in the U.S. and Canada. In the U.S., incidence jumped from 3.6 to 7.3 per 1,000 births from 2009 to 2013, study authors wrote.

Many women are first introduced to opioids as a method of postoperative pain management control. According to researchers, no previous literature assesses the potential link between postoperative opioid use and neonatal abstinence syndrome in future pregnancies.

“This is a novel question they are asking,” Kjersti Aagaard, MD, of Baylor College of Medicine in Houston, who was not involved with the research, told MedPage Today.

But while she said this question is unique to the current scope of literature, Aagaard also said this research makes a huge leap.

“They don’t look at what each woman had in terms of opiate pain control,” she said.

Indeed, Auger and colleagues wrote that they were unable to identify the type of drug used for postoperative pain management control in these women. But Auger told MedPage Today separately that infants with withdrawal symptoms were highly likely to be exposed to opioids while in the womb.

“There are a small proportion of infants that withdrawal symptoms can be due to other things,” Auger said, adding that sometimes antidepressants may cause withdrawal symptoms, but that is an exception. “Most of them are due to opioids.”

Researchers conducted a large retrospective cohort study of over 2 million births that occurred from 1989 to 2016 in Quebec, Canada. Using hospital discharge records, the researchers identified infants diagnosed with neonatal abstinence syndrome. Women who had surgery before pregnancy were identified by data stating use of general, local, or regional anesthesia any time before conception or during pregnancy.

Researchers accounted for confounders such as comorbidities at or before surgery, mental illness, age at delivery, parity, socioeconomic status, place of residence, and time period of delivery.

Overall, there were 2,346 neonates with neonatal abstinence syndrome, for a prevalence of 10.7 per 10,000 infants (95% CI 10.3–11.2). Among infants with NAS, 1,052 had mothers who underwent pre-pregnancy surgery (14.9 per 10,000), and 1,294 had mothers with no surgery (8.8 per 10,000).

The authors found that women who were younger at the age of their first surgery had higher relative risks despite their number of operations. Women who had multiple surgeries and were age 15 or younger at the time of their first operation were about 2.8 times as likely to have a baby that developed NAS compared to women with no surgery (95% CI 2.32–3.37). Women with only one surgery at that age had just over double the risk (RR 2.08, 95% CI 1.71–2.54).

“I think what the results show is just how addictive opioids are,” Auger told MedPage Today.

While surgeries under all specialties increased the risk of a baby developing NAS, women who underwent cardiovascular or thoracic surgery (RR 4.45, 95% CI 2.87–6.91), neurosurgery (RR 3.00, 95% CI 1.56–5.77), and urologic surgery (RR 3.03, 95% CI 2.16–4.26) had the highest likelihoods of having a baby with neonatal abstinence syndrome compared to women with no surgery.

This study was limited by the possible misdiagnosis of neonatal abstinence syndrome, and the difficulty of identifying pregnant women that used opioids. Researchers could not identify the type of opioid used or the duration of usage, and were also unable to identify the severity of symptoms in infants with NAS.

The research suggests the danger of opioid use in young women, as surgery is associated with opioid use that may persist in future pregnancies. But Aagaard added that variables that could not be identified prevent this research from reaching definitive conclusions.

“This study, I think, is good in its question and it’s an important issue to raise,” Aagaard said. “But I think the study as it stands now raises a lot more questions than answers.”

This study was funded by the Canadian Institutes of Health Research and the Fonds de recherche du Québec-Santé.

Authors disclosed conflicts of interest from the Canadian Institutes of Health Research and the Fonds de recherche du Québec-Santé during the conduct of the study.

No other competing interests were declared.