Adenomyosis occurs when the tissue that normally lines the uterus grows into the muscular wall, known as the myometrium. This misplaced tissue continues to act as it would in the lining, causing the uterus to become enlarged and thickened. Although the condition does not prevent pregnancy entirely, it introduces significant challenges to both conception and the maintenance of a healthy pregnancy.
How Adenomyosis Impacts Conception
Adenomyosis creates a hostile environment within the uterus that interferes with the earliest stages of reproduction. The invasion of endometrial tissue into the muscle wall causes chronic inflammation and structural changes that disrupt normal uterine function. This inflammatory state can be toxic to the developing embryo and make the uterine lining less receptive to implantation.
The condition alters the natural movements of the uterus, known as uterine peristalsis. Women with adenomyosis often exhibit hyperperistaltic contractions, which are excessive and dysfunctional movements of the inner myometrium. These abnormal contractions can disrupt the transport of sperm toward the fallopian tubes and interfere with the delicate process of an embryo embedding itself in the uterine wall.
Changes in the myometrium also affect the junctional zone, the boundary between the inner myometrium and the endometrium. Disruption of this architecture can impair the necessary mechanisms for successful implantation and subsequent conception. These factors combine to reduce the chances of a successful pregnancy, sometimes lowering conception rates by approximately 15 to 25%.
Treatment Pathways to Improve Fertility
Treatment for women with adenomyosis trying to conceive focuses on suppressing lesions and optimizing the uterine environment before pregnancy. One of the most common and effective medical approaches involves the use of gonadotropin-releasing hormone (GnRH) analogs. These medications work by temporarily inducing a hypoestrogenic state, which helps to shrink the adenomyotic tissue and reduce the associated inflammation.
This “down-regulation” period, often lasting three to five months before a planned conception, is particularly beneficial when followed by assisted reproductive technology (ART). Studies have shown that pretreatment with GnRH agonists can significantly increase the live birth rate and decrease the miscarriage rate for patients undergoing frozen embryo transfer (FET). This strategy allows the uterus to recover and enhances endometrial receptivity before an embryo is introduced.
Surgical options are reserved for specific cases, particularly those with localized adenomyosis, often referred to as an adenomyoma. A procedure called adenomyomectomy involves the surgical removal of these focal lesions while preserving the rest of the uterus. While complex, this surgery can improve fertility outcomes, with some reports showing higher delivery rates when the localized adenomyosis is completely excised.
Assisted Reproductive Technology, most notably in vitro fertilization (IVF), remains a primary pathway for many women with adenomyosis. While adenomyosis can negatively affect IVF outcomes, preparatory treatment helps mitigate these risks. The combination of medical suppression with GnRH analogs, followed by a frozen embryo transfer cycle, is often the preferred protocol to maximize success rates.
Addressing Pregnancy Complications
Once a pregnancy is established, the presence of adenomyosis shifts the concern from conception difficulty to the potential for complications during gestation. The structural and inflammatory changes in the uterine wall are linked to several elevated risks compared to pregnancies in women without the condition. One of the most frequently reported issues is an increased risk of miscarriage, especially in the first and second trimesters.
The abnormal uterine environment interferes with the development of the placenta, leading to a higher incidence of placental issues. These risks include placental malposition, such as placenta previa where the placenta covers the cervix, and placental abruption, the premature detachment of the placenta from the uterine wall. Such conditions can result in significant bleeding and require close medical management.
Adenomyosis is associated with an increased risk of preterm labor and delivery (birth before 37 weeks of gestation). The altered and thickened myometrium may be more prone to premature contractions, leading to an earlier delivery. Additionally, the condition is linked to a higher prevalence of small for gestational age (SGA) infants and fetal growth restriction (FGR) due to impaired blood flow and nutrient delivery to the fetus.
Prognosis and Ongoing Monitoring
Despite the challenges adenomyosis presents to both fertility and pregnancy, many women successfully carry pregnancies to term. The prognosis is significantly improved with early diagnosis and proactive treatment before conception. Consulting with a reproductive specialist allows for personalized strategies, such as medical down-regulation, to optimize the uterine environment prior to embryo transfer.
During pregnancy, a diagnosis of adenomyosis necessitates high-risk obstetric monitoring. This involves more frequent ultrasounds to closely monitor fetal growth and the location and health of the placenta. Careful tracking detects potential issues like preterm labor or growth restriction early, allowing for timely intervention and management.