Infants also at risk from mothers' endometriosis

Findings of a Danish retrospective cohort study show that women with endometriosis are at significantly increased risk for experiencing a variety of adverse pregnancy outcomes.¹

According to the authors of the recently published study, the research represents the largest and most detailed study of obstetrical and neonatal complications in women with endometriosis. They stated that its results confirm the findings of previously reported large studies. Considering the magnitude of the complications, the authors recommended increased antenatal surveillance for women with endometriosis.

Risks of obstetrical and neonatal complications among women with endometriosis were analyzed using data from the Danish Health Register and the Danish Medical Birth Register. The study population was comprised of women ages 15 to 49 years old who delivered in Denmark from 1997 through 2013. It included 11,739 women with a diagnosis of endometriosis who gave birth to 19,331 infants. The “unexposed” control cohort included 615,533 women who gave birth to 1,071,920 infants.

Results from multivariate logistic regression analysis adjusting for year of delivery and maternal age showed that compared to controls, women with endometriosis had a statistically significant increased risk for having pre-eclampsia (1.4-fold), severe preeclampsia (1.7-fold), hemorrhage in pregnancy (2.3-fold), placental abruption (2.0-fold), placenta previa (3.9-fold), premature rupture of membranes (1.7-fold), retained placenta (3.1-fold), and hemorrhage after 22 gestational weeks (2.3-fold).

Analyses of neonatal complications showed significantly increased risks of preterm birth before 28 weeks (3.1-fold) and before 34 weeks (2.7-fold), being small for gestational age (1.5-fold), a low Apgar score (1.4-fold), a diagnosis of a malformation within the first year (1.3-fold), and neonatal death (1.8-fold) for infants born to women with endometriosis.

The investigators also performed a subgroup analysis to assess risks in primiparous women with a singleton pregnancy and found the risk estimates for most outcomes were largely unchanged.
Findings of another subgroup analysis showed complications risks were higher among women who underwent surgery for endometriosis prior to pregnancy. The investigators considered a surgical history a marker for severe endometriosis.

The risks of most complications among women with endometriosis were reduced after adjustment for having had assisted reproductive techniques (ART), although they were still significantly increased. The investigators noted adjustment for ART also adjusted for severe endometriosis as well as for twin pregnancies.

Discussing their study limitations, the investigators said that the control cohort may have included some women with undiagnosed endometriosis who were not captured in the national registers. However, such misclassification would likely lead to underestimation of the risk of complications in women with endometriosis.

They also acknowledged that information on histological confirmation of endometriosis was not available.

Although they considered a history of surgery for endometriosis as a surrogate for having more severe disease, they raised the possibility that surgery may also affect pregnancy outcomes by its effects on the intrauterine environment. Therefore, they called for further research investigating the effect of abdominal surgery.

Reference

1. Berlac JF, Hartwell D, Skovlund CW, Langhoff-Roos J, Lidegaard Ø. Endometriosis increases the risk of obstetrical and neonatal complications. Acta Obstet Gynecol Scand. 2017 Feb 9. [Epub ahead of print]