Endometriosis may be linked to a reduction in live births before diagnosis of the condition, research suggests.
According to the study, the disease is associated with a reduction in fertility in the years before a definitive surgical diagnosis.
Researchers suggest the possible effect of endometriosis on the desired number of children highlights the importance of early diagnosis and treatment of the disease.
In the first study to look at birth rates in a large group of women who eventually received a surgical verification of the condition, researchers found the number of first live births in the period before diagnosis was half that of women without the painful condition.
Our findings suggest that doctors who see women suffering from painful menstruation and chronic pelvic pain should keep in mind the possibility of endometriosis and treat them effectively— Professor Oskari Heikinheimo, Helsinki University Hospital
This was the case regardless of what form of endometriosis the women had – ovarian, peritoneal, deep endometriosis or other types.
In addition, researchers found evidence the number of babies women had before diagnosis was significantly reduced, compared with women who did not have the chronic inflammatory condition that affects up to about one in 10 women of child-bearing age.
In women who have endometriosis, tissue from the lining of the womb grows in other places, such as the ovarian and fallopian tubes.
Symptoms include painful menstruation, pain in the pelvic area, difficult or painful sex and difficulty getting pregnant.
Correct diagnosis is often delayed by around seven years, and surgery has traditionally been the gold standard for diagnosing the condition and classifying the type of endometriosis, researchers say.
Professor Oskari Heikinheimo, of Helsinki University Hospital in Finland, who led the study, said: “Our findings suggest that doctors who see women suffering from painful menstruation and chronic pelvic pain should keep in mind the possibility of endometriosis and treat them effectively.
“Doctors should discuss with these women the possible effects on their fertility, in addition to the effects of their age, and the impairment of fertility should be minimised by offering relevant treatment for endometriosis without delay.”
Until now, there has been little information about the live birth rate among women with endometriosis, and little is known about the possible effects of different types of endometriosis on fertility, especially in the years before a diagnosis.
Prof Heikinheimo said: “Given the chronic nature and typical long delay in diagnosis of endometriosis, we wanted to find out if there were differences in first birth rates before diagnosis in a large group of women in the population.”
The study looked at 18,324 women in Finland, aged between 15 and 49, who had been diagnosed with endometriosis between 1998 and 2012 after surgery.
They matched them with 35,793 women of similar age who did not have the condition.
The group of women with endometriosis was also divided into four groups according to the type of endometriosis.
The average time of follow-up before surgical diagnosis was 15.2 years, and the average age at the time of diagnosis of endometriosis was 35 years.
A total of 7,363 women (40%) with endometriosis and 23,718 women (66%) without it delivered a live born baby during the follow-up period.
When analysed according to women’s birth decade from the 1940s to 1970s, the birth rate decreased in both groups of women, the study found.
Over the decades, an increasingly lower first live birth rate was seen in women with endometriosis, compared with women without.
In women born in 1940-1949, the difference in live birth rates between the two groups was 28% before surgically diagnosed endometriosis, but this difference increased steadily to 87% by 1970-1979.
Prof Heikinheimo said: “We assume that this is associated with the older age of women when they have their first baby, earlier surgical diagnosis of endometriosis and accumulating adverse effects of endometriosis in women affected by the condition.”
The number of children that women had before their diagnosis of endometriosis was 1.93 and 2.16 for women without endometriosis.
The findings are published in the Human Reproduction journal.
