These new findings, which were published online in JAMA Network Open, suggest that changing monitoring strategies to prevent preterm birth for women with the disease may not be necessary.
The research team, led by Louis Marcellin, MD, PhD, with the department of obstetrics and gynecology at Université de Paris, also found that disease phenotype or whether the preterm birth was induced or spontaneous did not appear to alter the result.
Those results differ from previous research. Data on the phenotypes and their link with preterm birth have been scarce, but previous studies have shown the risk for preterm birth is more pronounced in women who have deep endometriosis than in women with ovarian endometriosis.
Dr. Marcellin said in an interview that “little is known about the impact of endometriosis on obstetric outcomes. In contrast to previous studies, we reported no differences in the risk for preterm delivery between women with endometriosis (34 of 470 [7.2%]) and those without endometriosis (53 of 881 [6.0%]), even when adjusted for multiple factors.”
The authors accounted for mother’s age, body mass index before pregnancy, birth country, number of times the woman had given birth, previous cesarean delivery, and history of preterm birth. After adjusting for potential confounders, endometriosis was not associated with preterm birth (adjusted odds ratio, 1.07; 95% confidence interval, 0.64-1.77).
The researchers found no differences among preterm births based on a mother’s endometriosis phenotype. Those phenotypes include Isolated superficial peritoneal endometriosis, ovarian endometrioma, and deep endometriosis.
“Monitoring pregnancy beyond the normal protocols or changing management strategies may not be warranted in cases of endometriosis,” Dr. Marcellin said.
More research on endometriosis’ potential link to birth outcomes is needed.
An expert not involved with the study said the new paper highlights important new avenues of research but should not be seen as the final word on the connection between endometriosis and preterm birth.
Of the 1,351 study participants (mean age, 32.9 years) who had a singleton delivery after 22 weeks’ gestation, 470 were assigned to the endometriosis group, and 881 were assigned to the control group.
The authors concluded that “pregnant women with endometriosis should not be considered to have an exceptionally high risk for preterm birth. However, further studies are needed to examine the potential for other adverse perinatal outcomes or specific but rare complications.”
Daniela Carusi, MD, said the difficulty with the study’s design is that “premature birth is not one problem or one disease.”
Many very different problems can all end with premature birth. Sometimes it’s an infection or inflammation or bleeding in the uterus or hypertension in the mother, for example, and all those things can lead to a preterm birth, she explained.
“This study inherently lumps all those things together,” said Dr. Carusi, who is director of surgical obstetrics and placental abnormalities in the department of obstetrics and gynecology at Brigham and Women’s Hospital, Boston. “It’s quite possible endometriosis can have a big impact in one of those areas and no impact in the other areas, but the study design wouldn’t be able to pick that up.”