Sexual disease linked to ectopic pregnancies

A REASON for the link between ectopic pregnancy and a sexual infection has been discovered by academics in Scotland.

Scientists at the University of Edinburgh found women who have had chlamydia are at greater risk of such pregnancies, in which the baby starts to grow before entering the womb, usually in the fallopian tubes. About one in 50 pregnancies is ectopic.

The latest cause of risk to be discovered is the lasting after- effect of chlamydia.

For the first time, the new study shows evidence of how the infection can increase the risk of an ectopic pregnancy. Researchers found women who had had chlamydia were more likely to produce a particular protein in their fallopian tubes.

Increased production of this protein, known as PROKR2, makes a pregnancy more likely to implant in the fallopian tube.

The study follows research last year, also by Edinburgh scientists, that showed production of a similar protein increased the likelihood of smokers having an ectopic pregnancy.

Chlamydia is the most common sexually transmitted infection in the UK. It can be treated but often goes undiagnosed as it can occur without symptoms. It is known to cause infertility as it can lead to scarring and blockages in the fallopian tube.

This latest research shows, however, that chlamydial infection linked to ectopic pregnancy causes much more subtle changes in the fallopian tube, without evidence of severe scarring.

The study, published in the American Journal of Pathology, was funded by Wellbeing of Women and the Medical Research Council.

Dr Andrew Horne, of the University of Edinburgh's Centre for Reproductive Biology, said: "We know that chlamydia is a major risk factor for ectopic pregnancy but until now we were unsure how the infection led to implantation of a pregnancy in the fallopian tube. We hope that this new information allows health care providers to give women accurate information about risks following chlamydial infection and to support public health messages about the importance of safer sex and chlamydia testing."

Last year's research found a chemical in cigarette smoke, called cotinine, triggered a chain reaction that increased PROKR1 in the fallopian tubes.

While this protein allows the pregnancies to implant correctly inside the womb, its presence in the fallopian tubes is believed to increase the risks of the egg implanting somewhere else.

That study found that women who smoked and developed an ectopic pregnancy had double the levels of this protein in their fallopian tubes compared with women who did not smoke and had previously had a healthy pregnancy.

Researchers believe too much PROKR1 prevents the muscles in the fallopian tubes from contracting, which then hinders the transfer of the egg to the womb.The study, funded by Well-being of Women, analysed tissue samples from female smokers and non-smokers, and from women who had previously had ectopic and healthy pregnancies.