Women with endometriosis have higher risks of developing gestational hypertension-preeclampsia, according to the results of a nationwide study in Taiwan. The findings highlight the need for at risk-women to be more closely monitored to ensure safer births.

The study, “Risk of gestational hypertension-preeclampsia in women with preceding endometriosis: A nationwide population-based study,” was published in the journal PLOS One.

Hypertension is the most common medical complication of pregnancy. The condition known as gestational hypertension (GH), or pregnancy-induced hypertension, is defined as a patient whose systolic blood pressure is equal or above 140 mmHg or whose diastolic blood pressure is equal or above 90 mmHg after 20 weeks of gestation, without the presence of proteinuria (the presence of excess proteins in the urine).

Approximately 2-5% of women with GH develop preeclampsia (PE), the main cause of maternal and perinatal morbidity and mortality.

Endometriosis has been associated with infertility, but very few studies have investigated the relationship between endometriosis and GH-PE. The studies that do exist have produced conflicting results.

Now, a team of researchers performed a nationwide population-based study, collecting data from the Taiwan National Health Insurance Research Database (NHIRD). They selected women previously diagnosed with endometriosis between 1998 and 2012 from the Longitudinal Cohort Dataset 2010 (LHID2010), a data subset of the NHIRD. This group was designated as the exposed group after women became pregnant. Women in the LHID2010 who were negative for endometriosis were selected and classified as the unexposed group.

Researchers assessed whether GH-PE had occurred during the pregnancy of women in both groups. They evaluated how a preceding endometriosis diagnosis influenced the risk for GH-PE.

Because women diagnosed with endometriosis are often prescribed Danatrol (danazol), researchers also investigated whether its use reduced the occurrence of GH-PE. The endometriosis group was then divided into two subgroups, according to Danatrol use.

“Among 6,300 women with a prior endometriosis diagnosis who were retrieved from a population of 1,000,000 residents, 2,578 (40.92%) had subsequent pregnancies that were eligible for further analysis and were compared with 10,312 pregnant women without previous endometriosis,” the authors wrote.

The analysis showed that women with prior endometriosis had higher incidence of GH-PE in subsequent pregnancies when compared to those without endometriosis, at 3.88% versus 1.63%, respectively. Study authors highlighted that prior endometriosis was associated with GH-PE, thereby constituting an independent and significant risk factor for GH-PE.

Researchers also found that women treated with Danatrol showed less risk for GH-PE than those who weren’t treated, at 3.13% and 4.05%, respectively. However, this difference was not considered statistically significant.

Overall, the findings show that pregnant women with preceding endometriosis have an increased probability of developing GH-PE relative to those without endometriosis. The use of Danatrol had no effects on reducing the risk of future GH-PE.

“We recommend that obstetricians and gynecologists should be aware of the increased risk of future GH-PE in women with previous endometriosis. 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,” the authors concluded.