Adenomyosis is a chronic condition where the tissue that normally lines the uterus (endometrium) grows into the muscular wall (myometrium). This misplaced tissue functions normally, thickening and bleeding during the menstrual cycle, but is trapped within the muscle. The resulting irritation and inflammation often lead to an enlarged uterus, and this article explores the relationship between this disorder and a woman’s ability to conceive.
Understanding Adenomyosis
Adenomyosis involves the growth of endometrial tissue deep inside the myometrium, causing surrounding muscle cells to enlarge. The condition manifests in two main ways: diffuse or focal. Diffuse adenomyosis spreads throughout the uterine wall, often leading to a globally enlarged uterus.
Focal adenomyosis is localized and may form a distinct, nodular mass called an adenomyoma, which contains endometrial tissue and muscle. Common symptoms include heavy menstrual bleeding (menorrhagia) and severe menstrual cramping (dysmenorrhea), although many women experience no symptoms at all.
The Clinical Link to Reproductive Challenges
Clinical evidence strongly associates adenomyosis with subfertility, meaning a reduced ability to conceive, though it does not cause absolute infertility in every case. Studies involving women undergoing Assisted Reproductive Technology (ART), such as in vitro fertilization (IVF), consistently show lower clinical pregnancy and live birth rates for those with the condition. For example, one meta-analysis suggested women with adenomyosis had a 28% reduction in the likelihood of clinical pregnancy with ART.
Adenomyosis is also linked to adverse pregnancy outcomes, including a significantly increased risk of miscarriage. The presence of adenomyosis, particularly the focal type, has also been correlated with an increased risk of preterm birth. This clinical association highlights the condition’s negative influence on both conception and the ongoing success of a pregnancy.
Biological Mechanisms Interfering with Fertility
The primary ways adenomyosis disrupts fertility involve altering the uterine environment and its mechanical function. The presence of misplaced endometrial tissue triggers a state of chronic inflammation within the uterine muscle, which creates a hostile environment for a developing embryo. This inflammatory response involves increased density of immune cells and inflammatory mediators, which can impair the molecular signaling necessary for successful implantation.
The condition also leads to a dysfunction in the uterine muscle known as uterine hyperperistalsis or dysmotility. The normal, subtle contractions of the myometrium are necessary for sperm transport and proper embryo positioning. However, adenomyosis causes abnormal, disorganized contraction waves that can mechanically disrupt sperm migration or physically interfere with the process of an embryo attaching to the uterine lining.
Furthermore, the persistent inflammation and molecular changes impact endometrial receptivity, which is the readiness of the lining to accept and nourish an embryo. The altered expression of various factors, including hormones and adhesion molecules in the endometrium of women with adenomyosis, makes the uterine lining less receptive. This impaired receptivity means that even a healthy embryo may fail to implant or may result in a non-viable pregnancy. The overall effect is a combination of mechanical interference, chronic molecular disruption, and a failure of the uterus to provide optimal conditions.
Fertility-Preserving Treatment Strategies
For women with adenomyosis who wish to conceive, treatment strategies focus on improving the uterine environment and maximizing the chances of successful embryo implantation. Medical management often involves a temporary course of gonadotropin-releasing hormone agonists (GnRHa) before attempting conception, either naturally or through ART. This treatment creates a temporary, medically induced menopause, which shrinks the adenomyotic lesions and reduces inflammation, thereby improving the chances of pregnancy.
When GnRHa is used as a pretreatment before an IVF cycle, particularly a frozen embryo transfer (FET) cycle, clinical pregnancy rates and live birth rates are often significantly improved. Surgical options, such as the excision of a focal adenomyoma, can also be considered, though the procedure is complex and carries a risk of complications, including a higher risk of uterine rupture in subsequent pregnancies. For many patients, Assisted Reproductive Technology remains a central part of the strategy, often combining medical suppression with a controlled embryo transfer.