Adenomyosis linked to nearly tripled odds of late miscarriage in Belgian cohort

Women with adenomyosis faced significantly higher odds of late miscarriage in a retrospective cohort study of 2,620 singleton deliveries at CHU Liège – Citadelle Hospital in Belgium, published in BMC Pregnancy and Childbirth. After adjustment for endometriosis, mode of conception and congenital uterine malformations, the odds of late miscarriage remained nearly three times higher among women with adenomyosis (adjusted odds ratio 2.95, 95% CI 1.04–7.15, p = 0.043). The unadjusted odds ratio was 3.88 (95% CI 1.62–9.34, p = 0.0077).

Rather than a simple random sample, the researchers constructed an outcome-enriched cohort by identifying pregnancies with predefined complications from the institutional delivery registry and pairing them with temporally adjacent uncomplicated deliveries. Adenomyosis was diagnosed on transvaginal ultrasonography using the Morphological Uterus Sonographic Assessment (MUSA) criteria and/or magnetic resonance imaging reports, with imaging assessed up to six weeks postpartum. Of the 2,620 deliveries analysed, 86 cases of adenomyosis were identified, representing 3.3% of the cohort.

The association with late miscarriage survived this adjustment, supporting an independent relationship between adenomyosis and late miscarriage in this cohort.

Beyond miscarriage, the study found that adenomyosis was associated with higher overall obstetric morbidity (OR 1.64, 95% CI 1.06–2.55, p = 0.03). Two placental disorders also showed elevated odds: placenta accreta spectrum (OR 2.44, 95% CI 1.15–5.20, p = 0.026) and placenta praevia (OR 3.48, 95% CI 1.21–10.03, p = 0.037). These findings align with the study’s secondary aim of examining placental disorders, which the authors note are often reported in association with adenomyosis in the existing literature.

The authors propose several biological mechanisms that could connect adenomyosis to these complications. Adenomyosis involves ectopic endometrial tissue within the myometrium, and the condition is associated with chronic inflammation, impaired uterine contractility and abnormal vascular remodelling. According to the researchers, these alterations may impair placental development, providing a plausible pathway by which the condition could contribute to both miscarriage and placental disorders. They suggest that affected pregnancies may benefit from increased clinical awareness and careful antenatal surveillance, particularly during the second trimester.

Adenomyosis is increasingly diagnosed in women of reproductive age, a trend the authors attribute to advances in imaging and the adoption of standardised diagnostic criteria. While its gynaecological symptoms have long been recognised, its obstetric consequences have remained less clearly defined, and the impact of adenomyosis on late miscarriage specifically has been poorly characterised until now.

The researchers caution that further prospective studies are needed, using pre-conception standardised imaging and detailed phenotyping, to clarify the underlying mechanisms and optimise clinical management. As a retrospective, single-centre design, the study cannot establish causation, and the relatively small number of adenomyosis cases—86 among 2,620 deliveries—means the confidence intervals around some estimates are wide. The diagnosis was also based on imaging reports assessed up to six weeks postpartum rather than pre-conception imaging, a limitation the authors’ proposed future research direction is intended to address.

Nevertheless, the study adds to a growing body of evidence that adenomyosis is relevant not only for fertility and gynaecological symptoms but also for the course of pregnancy itself. The authors suggest that affected pregnancies may benefit from increased clinical awareness and careful antenatal surveillance, particularly during the second trimester, while noting that further prospective studies are needed to clarify underlying mechanisms and optimise clinical management.

Subject of Research: The association between adenomyosis and late miscarriage and other obstetric complications in a retrospective delivery cohort

Article Title: Association between adenomyosis and late miscarriage: a retrospective cohort study

Article References: Timmermans, M., El Sayed, S., Mélotte, S., Henry, L., Nisolle, M., & Chantraine, F. (2026). Association between adenomyosis and late miscarriage: a retrospective cohort study. BMC Pregnancy and Childbirth. https://doi.org/10.1186/s12884-026-10024-4

Image Credits: AI Generated

DOI: 10.1186/s12884-026-10024-4

Keywords: adenomyosis, late miscarriage, placenta accreta spectrum, placenta praevia, obstetric morbidity, retrospective cohort study, MUSA criteria, transvaginal ultrasound, placental disorders, BMC Pregnancy and Childbirth, Association, between