Adenomyosis is a condition where the tissue that normally lines the inside of the uterus (endometrium) grows into the muscular wall (myometrium). This misplaced tissue responds to hormonal cycles, causing the uterine wall to thicken, become inflamed, and sometimes enlarge significantly. This abnormal growth disrupts the uterus’s structure and function, creating a challenging environment for pregnancy. Understanding this interaction is important for individuals trying to conceive or who are currently pregnant.
Effects on Fertility and Conception
Adenomyosis interferes with reproduction, creating barriers to both natural conception and assisted reproductive technologies. The growth of endometrial tissue into the muscle wall causes chronic inflammation and a distorted, enlarged uterus. This altered structure impedes the movement of sperm and egg, known as uterotubular transport, which is necessary for fertilization.
The primary challenge in achieving pregnancy often lies in implantation, the process by which the embryo attaches to the uterine lining. The inflammatory state within the uterus, characterized by an increase in immune cells and inflammatory mediators, creates an environment that can be toxic to a developing embryo. Furthermore, thickening of the junctional zone (the boundary between the endometrium and myometrium) may block the embryo from securely embedding itself. Women with adenomyosis may also have reduced responsiveness to progesterone, a hormone crucial for preparing the uterine lining for implantation.
Adenomyosis affects the myometrial muscle contractions within the uterus. Hyper-peristaltic, or overly frequent and strong, uterine contractions have been observed in individuals with the condition, which may actively push the embryo away from the implantation site. Consequently, for women undergoing in vitro fertilization (IVF), adenomyosis is associated with lower rates of implantation, clinical pregnancy, and live births compared to those without the condition.
Risks During Early and Mid-Pregnancy
Once pregnancy is established, the structural and inflammatory changes caused by adenomyosis continue to pose specific risks during the first and second trimesters. Chronic inflammation and poor decidualization (the transformation of the uterine lining to support pregnancy) increase the likelihood of early pregnancy loss. The miscarriage rate is significantly higher in women with adenomyosis, including an increased risk of second-trimester miscarriage.
Localized bleeding is another common complication, often stemming from the ectopic endometrial tissue within the myometrium. This tissue continues to respond to pregnancy hormones, which can lead to localized destruction and bleeding within the uterine wall. The presence of adenomyotic lesions, particularly if they are large or focal (adenomyomas), can also cause heightened discomfort and pelvic pain during pregnancy as the uterus stretches.
In rare cases, a focal adenomyoma may rupture, especially as the uterus expands in the second trimester, leading to acute abdominal pain and potentially serious complications. The structural disruption means the uterus is less able to expand smoothly, sometimes resulting in unexpected symptoms or increased tenderness. The abnormal uterine environment also contributes to a higher risk of ectopic pregnancy.
Late-Stage Complications and Delivery Outcomes
The impact of adenomyosis becomes more pronounced in the third trimester, primarily affecting the placenta’s function and the timing of delivery. The abnormal structure and chronic inflammation of the uterine wall interfere with placentation (the deep embedding and development of the placenta). This defective placental development is linked to several severe obstetric complications. These include an elevated risk of placenta previa, where the placenta covers the cervix, and placental abruption, where the placenta prematurely separates from the uterine wall.
The compromised blood flow and restricted expansion of the myometrium can also lead to fetal growth problems. Adenomyosis is associated with a higher incidence of delivering a small-for-gestational-age infant due to insufficient nutrient and oxygen supply. Furthermore, the increased uterine irritability and abnormal contractility significantly raise the risk of preterm birth, defined as delivery before 37 weeks of gestation. Women with adenomyosis are up to twice as likely to deliver prematurely, which is also linked to an increased risk of preterm premature rupture of membranes (PPROM).
At the time of delivery, adenomyosis increases the likelihood of needing a Cesarean section, often due to the associated complications like placenta previa or fetal distress. A serious risk immediately following delivery is postpartum hemorrhage (PPH), or severe bleeding after birth. This occurs because the muscular wall of the uterus, infiltrated by adenomyotic tissue, may fail to contract effectively, a condition known as uterine atony.
Monitoring and Management During Gestation
Pregnant individuals with adenomyosis require specialized care and increased surveillance throughout their gestation. This heightened monitoring is necessary to identify and manage the potential complications associated with the condition. More frequent ultrasound examinations are often scheduled to assess fetal growth and monitor the development and location of the placenta.
Special attention is given to monitoring the cervix for signs of shortening or funneling, which can indicate an increased risk of preterm labor. Managing pain is also a consideration, although treatment options are limited during pregnancy to avoid compromising the fetus. Healthcare providers focus on strategies that are safe for the developing baby, sometimes including heat therapy or select pain relievers, only after careful consultation.
A multidisciplinary approach involving both obstetricians and maternal-fetal medicine specialists is frequently employed to manage these high-risk pregnancies. In certain cases, interventions like low-dose aspirin may be considered to potentially improve placental blood flow and reduce the risk of preeclampsia, a hypertensive disorder linked to adenomyosis. The goal of this focused management plan is to support the pregnancy to term and mitigate the risk of adverse outcomes for both the parent and the infant.