While endometriosis has been associated with infertility for decades, a new study concludes that pregnant women with the condition are at greater risk for complications during pregnancy and at delivery.

Vincenzo Berghella, director of maternal fetal medicine at Thomas Jefferson University Hospitals, was the lead author of the report. He says the results surprised him.

"When we came up with this study, as a clinician, my personal take was that we weren't going to find anything," he said. "In the past, if a pregnant patient said they had endometriosis, given the infertility issues, the ob-gyn would say, 'Great, you're pregnant.' But now, you have to be aware of the risks."

"It's important that women with a history of endometriosis, and obstetricians caring for them, are aware of this association," Berghella said. "These pregnancies deserve closer monitoring for these complications."

Twenty-four previous studies were included in the meta-analysis, which included data on more than a million women. Results showed that women had a higher risk of preterm birth, miscarriage, cesarean delivery, and placenta previa (low-lying placenta, a condition that can lead to bleeding during pregnancy). Endometriosis was also associated with birth of infants who were small for their gestational age. No association was seen between endometriosis and gestational hypertension or preeclampsia, a life-threatening condition.

"Endometriosis is known to alter a woman's physiology in a way that could interfere with a number of stages of pregnancy," Berghella said. "From causing inflammation at the endometrium, to resisting the action of progesterone during implantation and throughout the pregnancy."

Endometriosis, in which the type of tissue that forms the lining of the uterus (the endometrium) can be found attached to other organs, affects about one in 10 women in the United States. Symptoms may include severe abdominal pain, prolonged menstrual periods, infertility, and painful intercourse, although some women experience none of these issues.

Often it takes up to 10 years to diagnose endometriosis, with some women not realizing that they have the condition until they try to become pregnant. Diagnosis is done using laparoscopy, in which a surgeon inserts a lighted viewing instrument called a laparoscope through a small incision.

The delay in diagnosis may be due to the fact that the symptoms can vary a great deal, and may suggest other conditions. Studies indicate that African American and Hispanic women may wait even longer than white women to be correctly diagnosed.

Claire Robinson, an ob-gyn at Einstein Hospital, says African American women, in particular, experience delays in having endometrial issues correctly diagnosed.
Einstein Hospital
Claire Robinson, an ob-gyn at Einstein Hospital, says African American women, in particular, experience delays in having endometrial issues correctly diagnosed.

"I deal with a very large African American population and I think it does get diagnosed a little later because assumptions are made that it's something else," said Claire Robinson, an ob-gyn at Einstein Hospital, who specializes in endometrial issues.

All of the study participants had undergone laparoscopy to ascertain if they had endometriosis or surgery to treat the condition.

"Even if you have surgery for endometriosis you can have these pregnancy issues," Berghella notes.

Robinson, however, notes that the study didn't differentiate between those who had become pregnant naturally and those who needed medical assistance to conceive.

"That complicates the issue," Robinson said. "Patients who get pregnant with assisted reproductive technologies, whether they have endometriosis or other problems that kept them from becoming pregnant, do get counseled about possible complications during pregnancy."

"The study is very helpful, but it skims the surface," Robinson said. "It presents more questions such as how do we change the course of these patients other than monitoring them more closely for potential complications. What can we change?"

Robinson says the study results should help doctors be more aware of risk factors "so that when patients present with certain complaints or problems we are a little more vigilant in doing testing. We might counsel patients that they need to be followed very closely, that they need to keep their appointments, and that they need to be compliant in the management of their pregnancy."

Currently, patients who are pregnant with endometriosis are not always considered high risk, Robinson said.

"The study will make us a little more aware of this problem and to counsel patients as to what evidence has been shown previously and what has been shown more recently to have possible effects on their pregnancy or well-being. It will impact on how we practice," she said.

In examining the study's conclusions, Berghella said additional research was needed to explain why women with endometriosis had more miscarriages or preterm births.

"What this means is that we need to watch these pregnant women more closely and consider these high-risk pregnancies,"  Berghella said.

"We need to give ultrasounds to check for the size of the baby, check the baby's anatomy, look for a short cervix, which can be a sign for delivering early, and check the placenta. These are all issues we should be aware of."