BACKGROUND: Spontaneous preterm labor (SPL) is a significant obstetric concern, and recent literature suggests an association with adenomyosis. In this study, we compared adenomyosis and endomyometrial junctional zone (JZ) in women with and without a recent history of SPL. METHODS: This case-control study was conducted between October 2019 and Mar 2021. Exclusion criteria included Iatrogenic preterm labor, a history of hormonal drug use after delivery, a history of Müllerian anomaly, endometriosis, fibroids, uterus surgery, cesarean section, and postpartum hemorrhage requiring uterine procedures. The study population consisted of women with a history of SPL or a history of full-term vaginal delivery within the last six months in the study and control groups, respectively. All participants underwent 2- and 3-dimensional transvaginal sonography six months after delivery to assess the JZ thickness and irregularity, and the presence or absence of adenomyosis. RESULTS: 92 women were included in this study. No significant differences were found regarding age, body mass index, parity, or prior preterm birth. The mean JZ irregularity was 2.53 ± 1.39 mm in the study group and 1.86 ± 0.72 mm in the control group (P = 0.004). In the overall cohort, increased JZ difference was associated with higher odds of SPL (aOR = 1.74). Stratifying by adenomyosis status showed that the association was stronger and remained significant in women with adenomyosis (aOR = 1.88), whereas it lost significance in those without adenomyosis. CONCLUSION: SPL is notably associated with the JZ characteristics and adenomyosis. Further studies are recommended to explore the relationship between these factors and pregnancy outcomes.
Moini et al. (Sun,) studied this question.