Adenomyosis and Its Impact on Reproduction, Pregnancy, Childbirth, and the Newborn

This narrative review covers the diagnosis of adenomyosis; its impact on fertility, assisted reproduction, pregnancy, childbirth, and the newborn; and its uterus-sparing management. Diagnosis is delayed by about 11 years, and no classification is universally accepted. After in vitro fertilization, adenomyosis lowers clinical pregnancy and live birth rates and doubles miscarriage risk. Because oocyte number and morphology are preserved and miscarriage remains increased with donor oocytes and euploid embryos, the deficit appears mainly uterine; however, age and coexistent endometriosis contribute. In pregnancy, it is associated with preeclampsia, preterm birth, placental malposition and placenta accreta spectrum, cesarean delivery, and postpartum hemorrhage, and newborns are more often small for gestational age, of low birth weight, and extremely preterm. The evidence is observational and of low to very low certainty, and defective remodeling of the junctional zone spiral arteries remains a hypothetical unifying mechanism. In selected observational cohorts, pregnancy was reported in approximately half of infertile women after uterus-sparing surgery, which has not been compared with medical treatment or assisted reproduction in randomized trials and carries a risk of uterine rupture. Management rests on individualized counseling; proposed preventive measures, including low-dose aspirin and correction of vitamin D or folate deficiency, remain untested in adenomyosis.