Association between adenomyosis volume and adverse perinatal outcomes: multicenter cohort study.

Objective: To assess the association between adenomyosis volume, as a reflection of its severity, and the risk of adverse perinatal outcomes.

Methods: This multicenter retrospective cohort study was conducted at a comprehensive tertiary care institution and a tertiary maternal and child healthcare hospital, which are the main types of hospital providing maternal medical care in China. The study included pregnant women without adenomyosis (non-AD cohort) who delivered between 1 January 2021 and 31 December 2021, and women with pregnancy complicated by adenomyosis (AD cohort) who delivered between 1 January 2020 and 31 December 2022. Adenomyosis was diagnosed and measured using transvaginal or transabdominal ultrasound up to 14 weeks of gestation. The adenomyosis volume (V) was calculated based on the sonographic measurement of three dimensions, using the formula V = (length × width × thickness) × 4/3π. Univariate and multivariate logistic regression analyses were conducted to assess the association between adenomyosis and the risk of pregnancy complications. We also performed a sensitivity analysis among 226 pregnancies complicated by adenomyosis that had volume measurements available and 10 507 pregnancies without adenomyosis, using as a threshold for severe adenomyosis the 3^rd quartile of adenomyosis volume.

Results: The study group included 10 507 pregnant women in the non-AD cohort and 321 in the AD cohort. Pregnancies complicated by adenomyosis had an increased risk of preterm birth < 37 weeks of gestation (adjusted odds ratio (aOR), 2.39 (95% CI, 1.65-3.48)), spontaneous preterm birth < 37 weeks of gestation (aOR, 2.57 (95% CI, 1.54-4.28)), placenta previa (aOR, 2.57 (95% CI, 1.41-4.67)), cervical incompetence (aOR, 9.70 (95% CI, 4.00-23.55)) and abnormal fetal presentation (aOR, 2.04 (95% CI, 1.39-3.00)), and there was also a non-significant trend toward increased risk of pre-eclampsia (aOR, 1.64 (95% CI, 0.94-2.85)). Sensitivity analysis revealed there was a greater risk in pregnancies with severe (≥ 757.5 cm³) vs mild adenomyosis of preterm birth < 37 weeks of gestation (aOR, 5.50 (95% CI, 2.80-10.82) vs aOR, 1.73 (95% CI, 0.98-3.05)), pre-eclampsia (aOR, 4.94 (95% CI, 2.11-11.58) vs aOR, 1.03 (95% CI, 0.41-2.58)), placenta previa (aOR, 6.37 (95% CI, 2.39-17.04) vs aOR, 1.58 (95% CI, 0.60-4.19)) and cervical incompetence (aOR, 12.79 (95% CI, 2.87-56.93) vs aOR, 4.97 (95% CI, 1.25-19.77)) compared to pregnancies without adenomyosis. The risk of spontaneous preterm birth < 37 weeks and the risk of abnormal fetal presentation was similar between the two subgroups.

Conclusion: Pregnancies complicated by adenomyosis, particularly those with severe adenomyosis, have an increased risk of pregnancy complications, including preterm birth, spontaneous preterm birth, placenta previa, cervical incompetence and abnormal fetal presentation. © 2024 International Society of Ultrasound in Obstetrics and Gynecology.