Women who undergo an endoscopy during pregnancy are increasing the chances that their baby will be born preterm, or be small for gestational age (SGA), according to research published in the February issue of Gastroenterology (doi: 10.1053/j.gastro.2016.10.016).
“Research in pregnancy outcome in women undergoing endoscopy during pregnancy is scarce,” wrote the authors, led by Jonas F. Ludvigsson, MD, of the Karolinska Institutet in Stockholm, adding that there are nine studies with original data on a total of 379 pregnant women undergoing endoscopy; two of these studies examined pregnancy outcome in upper endoscopy (n = 143), two examined pregnancy outcome in sigmoidoscopy or colonoscopy (n = 116), and four examined pregnancy outcome in endoscopic retrograde cholangiopancreatography (n = 120).
Additionally, the authors noted that, to their knowledge, there are no studies that offer data on the relative risk of endoscopy during pregnancy, and none that followed up subjects after birth. Of the few studies that do exist, a handful conclude that endoscopy during pregnancy is actually safe, but do not include data on stillbirths and neonatal deaths that did not occur immediately after patients underwent endoscopy, which could compromise that data.
To address the lack of reliable research on the effect of endoscopy on pregnancy, Dr. Ludvigsson and his coinvestigators launched a nationwide study of pregnancies in Sweden that occurred between 1992 and 2011, all of which were registered in the Swedish Medical Birth Registry and the Swedish Patient Registry. The databases revealed 2,025 upper endoscopies, 1,109 lower endoscopies, and 58 endoscopic retrograde cholangiopancreatographies, for a total of 3,052 pregnancies exposed to endoscopy over that time period.
The primary endpoint of the study was the frequency of preterm birth and stillbirth in this population. To measure this, the investigators used adjusted relative risk (ARR), calculated via Poisson regression by using data on 1,589,173 pregnancies that were not exposed to endoscopy as reference.
“Stillbirth is recorded from 22 completed gestational weeks since mid-2008, and before that from gestational week 28. Gestational age was determined using ultrasound, and when ultrasound data were missing, we used the first day of the last menstrual period for pregnancy start,” the authors wrote.
The results showed that mothers who had any kind of endoscopy during pregnancy were more likely to experience a preterm birth or give birth to a baby who was SGA, with the ARR being 1.54 (95% confidence interval, 1.36-1.75) and 1.30 (95% CI, 1.07-1.57), respectively. However, the risk of other adverse effects, such as stillbirth or congenital malformation, was not significant: Stillbirth ARR was 1.45 (95% CI, 0.87-2.40) and congenital malformation ARR was 1.00 (95% CI, 0.83-1.20).
Women who were exposed to endoscopy during pregnancy were more likely to have a preterm birth, compared with women who had endoscopy 1 year before or after pregnancy, but were not more highly predisposed to SGA, stillbirth, or congenital malformations. Additionally, when data on multiple pregnancies carried by the same mother were compared, no correlation was found between endoscopy and gestational age or birth weight, if the mother was exposed to endoscopy during only one of the pregnancies.
“Earlier recommendations suggest that endoscopy should only be performed during pregnancy if there are strong indications, and if so, not during the second trimester, [but] our study shows that endoscopy is unlikely to have a more than marginal influence on pregnancy outcome independently of trimester,” the authors concluded. “Neither does it seem that sigmoidoscopy is preferable to a full colonoscopy in the pregnant woman.”
Regarding the latter conclusion, the authors clarified that “it is possible that in women with particularly severe gastrointestinal disease where endoscopy is inevitable, the physician will prefer a sigmoidoscopy rather than a full colonoscopy, and under such circumstances the sigmoidoscopy will signal a more severe disease.”
The investigators also noted that their study had several limitations, including not knowing the length of time each endoscopy took, the sedatives and bowel preparations that were used, the patient’s position during the procedure, and the indication that prompted the endoscopy in the first place.
The study was funded by grants from the Swedish Society of Medicine and the Stockholm County Council, and the Swedish Research Council. Dr. Ludvigsson and his coauthors did not report any relevant financial disclosures.