The Risk of Adverse Pregnancy Outcomes Following Nonobstetric Surgery During Pregnancy

Abstract

Objective: The aim of this study was to estimate the risk of adverse birth outcomes for women who underwent nonobstetric surgery during pregnancy compared with those who did not. Background: Previous research suggests that nonobstetric surgery occurs during 1% to 2% of pregnancies. However, there is limited evidence quantifying risks to the mother or pregnancy of such surgery. Methods: We examined maternity admissions using hospital administrative data collected between April 1, 2002, and March 31, 2012, and identified pregnancies wherein nonobstetric surgery occurred. We used logistic regression models to determine the adjusted relative risk, attributable risk, and number needed to harm of nonobstetric surgical procedures for adverse birth outcomes. Results: We identified 6,486,280 pregnancies. In 47,628 of these pregnancies, nonobstetric surgery had occurred. We found that nonobstetric surgery during pregnancy was associated with a higher risk of adverse birth outcomes, although the attributable risk was generally low. We estimated that every 287 surgical operations were associated with 1 additional stillbirth, every 31 operations associated with 1 additional preterm delivery, every 39 operations associated with 1 additional low birth weight baby, every 25 operations associated with 1 additional caesarean section, and every 50 operations associated with 1 additional long inpatient stay. Conclusions: Although we have no means of disentangling the effect of the surgery from the effect of the underlying condition, we found that the risk associated with nonobstetric surgery was relatively low, confirming that surgical procedures during pregnancy are generally safe. We believe that our findings improve upon previous research, and are useful reference points for any discussion of risk with prospective patients.Keywords: complications, obstetric, pregnancy, safety, surgery (Ann Surg 2017;266:260-266) T raditional teaching states that there is an increased risk of miscarriage, stillbirth, and preterm labor when a pregnant woman undergoes surgery under general anesthesia during pregnancy.1 This risk has however never been quantified and such risks may have decreased with the use of modern anesthetic agents and techniques. At present, when counseling a pregnant woman on this risk, the information provided is not robustly evidence-based.Previous research suggests that 1% to 2 % of women undergo nonobstetric surgery during pregnancy, 2 common operations being appendicectomy, cancer surgery, and orthopedic procedures. Research has also suggested that nonobstetric surgery during pregnancy is associated with adverse birth outcomes: a Canadian study of 2565 pregnant women reported an increased risk of spontaneous abortion after a general anesthetic [relative risk (RR) ¼ 1.58, 95% confidence interval (95% CI) 1.19-2.09];3 and a Swedish registry study showed associations between nonobstetric operations during pregnancy and low birth weight. 4 A systematic review brought these and many smaller studies together.5 In this analy...

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“…On the other hand, surgery during pregnancy increases the risks for hypopituitarism, abortion in the first trimester and fetal loss in the last trimester. Therefore, surgery should be avoided or postponed as much as possible (67) and preferably performed in centers with large experience.…”

Estimating the risk of adverse birth outcomes in pregnant women undergoing non-obstetric surgery using routinely collected NHS data: an observational study

“…Further research is required to evaluate the association of non-obstetric surgery and spontaneous abortion. 54 l We have already engaged with the British Society of Endocrine and Thyroid Surgeons and the Association of Breast Surgery, both of which have guidelines. Both organisations have agreed to consider hosting guidance that we produce on their websites.…”

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“…Historically, general anesthesia and nonobstetric surgery during pregnancy were reported to be related to a higher incidence of prematurity and intrauterine growth retardation [19] and abortion [20, 21]. However, recent clinical data suggested that general anesthesia in pregnant patients may not have as much potential for harm as previously thought [22, 23].…”