A number of risk factors have been found for gestational hypertension/preeclampsia (GH-PE), and a new study from Taiwan suggests endometriosis is one of them, and a significant and independent risk factor at that. Using Taiwan’s National Health Insurance Research Database, the authors conducted a nationwide, population-based, longitudinal study and found that women with previous endometriosis had a 3.88% chance of developing GH-PE compared to a 1.63% elevated risk in healthy controls without previous endometriosis. The difference was significant at P < 0.0001. Upon further analysis, the team found that the adjusted odds ratio for development of GH-PE after prior endometriosis was 2.27 (95% confidence interval: 1.76-2.93).
Starting with a population of 1 million residents of Taiwan who were insured by National Health Insurance, a single-payer health insurance program, in 2010, and culling down to 6,300 women aged 15 to 45 with a prior tissue-proven diagnosis of endometriosis, the researchers compared pregnancies in 2,578 women who had been diagnosed with endometriosis prior to conceiving to those in 10,312 pregnant women without endometriosis.
Approximately 6% to 8% of pregnant women will be diagnosed with GH, which is defined as a systolic blood pressure > 140 mmHg or a diastolic blood pressure > 90 mmHg after 20 weeks of pregnancy but without presence of proteinuria. Two percent to 5% of women with GH will develop PE.
Other risk factors for GH-PE include older age, first pregnancy, obesity prior to pregnancy, multifetal pregnancy, polycystic ovary syndrome, chronic kidney disease, diabetes mellitus, and autoimmune diseases. The authors noted that these risk factors only predict one- third of women who will develop GH-PE, the most common medical complication of pregnancy. Prior to their study, they found only three studies that looked at endometriosis as a potential risk factor, and these studies had conflicting results.
The authors suggested that there are multiple, complicated factors linking endometriosis and GH-PE, such as presumed activation of macrophages and modulation of natural killer (NK) cells by the disease, along with endometriosis-associated chronic oxidative stress and inflammation of the epithelium and stromal cells.
The researchers also investigated the impact of danazol use for endometriosis on risk of GH-PE, finding that it reduced the risk slightly but not significantly. Pregnant women with previous endometriosis who had been treated with danazol (n=480) had a GH-PE incidence of 3.13% while those who were not treated with the drug (n=2,098) had an incidence of 4.05%. This translated to an adjusted odds ratio of 1.49 (95% CI 0.86-2.56). The lack of significance may have been related to the fact that women using danazol had more severe disease than non-users, the investigators stated.
Early recognition can reduce complications
It is important to recognize a woman’s endometriosis status during pregnancy so that she can be surveilled more closely, said the researchers, and perhaps referred to a specialist. “When at-risk women become pregnant, monitoring and preparation should be intensified before and during delivery to avoid obstetric complications due to the high risk of GH-PE,” they concluded in the paper, which was published in the journal PLOS One.