Rising number of Swedish women suffer recurrent miscarriages
A new Swedish study indicates that a rising number of women have experienced three or more miscarriages in a row. The medical researchers are uncertain as to the cause.
If a woman experiences three or more miscarriages without giving birth successfully between them, she is diagnosed with recurrent pregnancy loss (RPL). This entitles her to an array of medical examinations to determine the cause of the failed pregnancies.
RPL is experienced by about one percent of all women who get pregnant. Sometimes the medical causes of multiple miscarriages are found: chromosome defects, deformities in the uterus or the autoimmune disease known as APS. Very often, however, doctors are at a loss to explain the failed pregnancies.
Emma Råsmark Røpke is a specialist in obstetrics and gynaecology at Skåne University Hospital in Sweden, with a doctorate from Lund University. In a new study, she and her colleagues have used the Swedish National Patient Register to investigate how many women were diagnosed with RPL in the period 2003–2012.
They were very surprised by the results. In the course of these ten years the number of cases rose 58 percent, from 533 women out of 100,000 pregnant women to 875 out of 100,000 pregnant women in 2012, according to their calculations.
“We can see an increase in the course of the entire decade, but it is stronger in the last five years,” says Røpke in a press release from the Skåne University Hospital.
Røpke and her colleagues calculated the rise amongst the 6,852 women in the ten-year period who were diagnosed with RPL in Sweden’s National Patient Register.
The researchers know little about how high the figure was before 2003, and thus cannot say whether the increase was a continuation of an upward curve, or whether recurrent pregnancy loss might have been even more common previously. Røpke explains that women in Sweden were of course diagnosed with it prior to 2003, but that was the year statistical information became reliable enough to use.
Norway lacks information that would indicate whether RPL is on the rise. Britt Ingjerd Nesheim is a professor emerita at Oslo University Hospital’s Division of Gynaecology and Obstetrics and she has researched this problem for years.
“If there is a real change in how many are experiencing recurrent pregnancy loss we have to ask ourselves whether we have something in our midst that is having an impact. This is a conspicuous increase,” says Nesheim, regarding the Swedish statistics.
She knows of no surveys of the number of women with RPL in Norway – or whether more have experienced it in the past decade, as the Swedish study indicates.
Looking for an explanation in the immune defence
The study says nothing about why a considerably larger number of Swedish women received the diagnosis in 2012 than in 2003.
There could be environmental factors or a higher impact on the immune defence system because other diseases linked to it have generally increased – allergies and inflammatory intestinal diseases, according to the press release from Skåne University Hospital.
Røpke stresses that the new study has not looked into possible reasons why there has been a rise in recurrent pregnancy loss every year.
“One can speculate on the grounds of register studies but there are clearly many possible explanations,” says Røpke.
She says one category that is often considered in recent years is immunological diseases.
“There could be something that triggers an immunological response against the pregnancy in an early stage. There is a fine balance between two types of immunological responses during pregnancy.”
“We are currently conducting another study in which we look for traces in the blood to determine whether women who experience recurrent pregnancy losses have a different response in their immune defence systems than women who have healthy pregnancies.”
A true increase?
Britt Ingjerd Nesheim suggests that if changes were made in the registration of women with the RPL diagnosis that could explain why more women having such miscarriages were registered in 2012 than ten years previously.
Røpke insists, however, that the diagnostics have not changed in this period, nor have registration methods been altered.
Røpke and her colleagues have only studied the women who actually were diagnosed with RPL.
“If a woman has a spontaneous miscarriage at home and does not contact medical help she will not be seen in the register,” says the Swedish researcher to ScienceNordic’s Norwegian partner forskning.no.
Nevertheless, these women usually do seek medical help for an examination and treatment – they actually want to have children. And thus they become registered.
“With this in mind there should not be an increase in those seeking help in 2012 as compared to 2003,” says Røpke.
However, she does not rule out other factors affecting the tally, for instance that more information became available about recurrent pregnancy loss, which in turn contributed to making more women seek help and thus tallied in the patient register.
Maybe the public health system has become more likely to examine these women than before.
“These are all speculations which unfortunately cannot be explained on the basis of this study,” says Røpke.
It is commonly estimated that about one in one hundred pregnant women experience three miscarriages in a row without having a successful pregnancy between them.
The Swedish study investigated how many new cases were diagnosed annually. In 2012 this average was just short of 0.9 out of 100 pregnant women – in other words a little lower than the common estimate of RPL.
Various treatments are available for women who suffer recurrent miscarriages, depending on prospective known causes for the miscarriages or even when doctors do not know the cause. Some women receive treatment which research has not designated as effective, but which might in theory be helpful. For instance women can be given progesterone supplements – a hormone that pregnancies depend on.
Røpke and her colleagues have conducted a meta-analysis of research studies to see what effect such treatment has had round the world.
“We have found out that it has no effect on women who are given it after becoming pregnant. This might be attributed to how the studies were conducted, but we don’t really know.”
“But a study in Egypt has indicated that progesterone treatment can have an impact if women receive if before their pregnancy, during ovulation.”
Translated by: Glenn Ostling
- E. R. Roepke et al.: Is the incidence of recurrent pregnancy loss increasing? A retrospective register-based study in Sweden. Acta Obstetricia et Gynecologica Scandinavica, 25 September 2017.
- A. M. Abbas et al.: Peri-conceptional progesterone treatment in women with unexplained recurrent miscarriage: a randomized double-blind placebo-controlled trial. The Journal of Maternal-Fetal & Neonatal Medicine, 15 February 2017. Abstract.
- N. Oldereid et al.: Habituell abort - gjentatte spontanaborter. Handbook, Norwegian Society for Gynecology and Obstetrics, 2015.