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Sep 27 10 9:37 PM
Smoking link to ectopic pregnancy
Research from experts at Edinburgh University said Cotinine triggered a reaction which increased a protein in the Fallopian tubes.
They said the protein, called PROKR1, raised the risk of an egg implanting outside the womb.
Details of the study were published in the American Journal of Pathology.
PROKR1 allows pregnancies to implant correctly inside the womb, but its presence in the Fallopian tubes is believed to increase the risks of this happening outside the womb.
The study found that women who smoked and developed an ectopic pregnancy had twice as much PROKR1 in their Fallopian tubes as women who did not smoke and had previously had a healthy pregnancy.
"This shows that components of cigarette smoke also enter the blood stream and affect seemingly unconnected parts of the body"
End Quote Dr Andrew Horne Edinburgh University Researchers believe that too much of the protein prevents the muscles in the walls of the Fallopian tubes from contracting, which in turn hinders the transfer of the egg to the womb.
Dr Andrew Horne, of the university's centre for reproductive biology, said: "This research provides scientific evidence so that we can understand why women who smoke are more at risk of ectopic pregnancies and how smoking impacts on reproductive health.
"While it may be easy to understand why inhalation of smoke affects the lungs, this shows that components of cigarette smoke also enter the blood stream and affect seemingly unconnected parts of the body like the reproductive tract."
The study, funded by Wellbeing of Women, analysed tissue samples from female smokers and non-smokers, and from women who had previously had ectopic and healthy pregnancies.
Smoking is thought to increase the risk of an ectopic pregnancy by up to four times.
There are more than 30,000 ectopic pregnancies in the UK each year, with the egg implanting in the Fallopian tube in 98% of cases.
This can cause the tube to rupture and lead to internal bleeding and fertility problems in the future.
Around one in 50 pregnancies in the western world is ectopic. The condition is the leading cause of maternal mortality in the first three months of pregnancy.
http://www.bbc.co.uk/news/uk-scotland-edinburgh-east-fife-11418432
Cotinine Exposure Increases Fallopian Tube PROKR1 Expression via Nicotinic AChR alpha-7. A Potential Mechanism Explaining the Link between Smoking and Tubal Ectopic Pregnancy American Journal of PathologyPublished online before print September 23, 2010 Julie L.V. Shaw, Elizabeth Oliver, Kai-Fai Lee, Gary Entrican, Henry N. Jabbour, Hilary O.D. Critchley, and Andrew W. Horne Abstract Tubal ectopic pregnancy (EP) is the most common cause of maternal mortality in the first trimester of pregnancy; however, its etiology is uncertain. In EP, embryo retention within the Fallopian tube (FT) is thought to be due to impaired smooth muscle contractility (SMC) and alterations in the tubal microenvironment. Smoking is a major risk factor for EP. FTs from women with EP exhibit altered prokineticin receptor-1 (PROKR1) expression, the receptor for prokineticins (PROK). PROK1 is angiogenic, regulates SMC, and is involved in intrauterine implantation.
We hypothesized that smoking predisposes women to EP by altering tubal PROKR1 expression. Sera/FT were collected at hysterectomy (n = 21). Serum levels of the smoking metabolite, cotinine, were measured by enzyme-linked immunosorbent assay. FTs were analyzed by q-RT-PCR, immunohistochemistry, and Western blotting for expression of PROKR1 and the predicted cotinine receptor, nicotinic acetylcholine receptor alpha-7 (AChR alpha-7). FT explants (n = 4) and oviductal epithelial cells (cell line OE-E6/E7) were treated with cotinine and an nAChR alpha-7 antagonist.
PROKR1 transcription was higher in FTs from smokers (P < 0.01). nAChR alpha-7 expression was demonstrated in FT epithelium. Cotinine treatment of FT explants and OE-E6/E7 cells increased PROKR1 expression (P < 0.05), which was negated by cotreatment with nAChR alpha-7 antagonist.
Smoking targets human FTs via nAChR alpha-7 to increase tubal PROKR1, leading to alterations in the tubal microenvironment that could predispose to EP. http://ajp.amjpathol.org/cgi/content/abstract/ajpath.2010.100243v1
Jan 27 11 9:51 AM
NEW YORK | Thu Dec 30, 2010
NEW YORK (Reuters Health) - A new study may offer women one more reason to kick the smoking habit before becoming pregnant: a potentially reduced risk of early miscarriage.
In a study of nearly 1,300 Japanese women with a past pregnancy, researchers found that those who smoked heavily early in pregnancy were more than twice as likely as non-smokers to suffer a miscarriage in the first trimester.
There are many reasons for women to quit smoking before becoming pregnant. The habit has been linked to increased risks of stillbirth, preterm delivery and low birthweight.
But studies so far have come to conflicting conclusions as to whether smoking might contribute to miscarriage risk.
These latest findings, reported in the journal Human Reproduction, support a connection.
For the study, researchers led by Dr. Sachiko Baba of Osaka University reviewed the records of 430 women who'd suffered a first-trimester miscarriage. They compared each woman with two others the same age who had given birth that same year.
Overall, the researchers found, women who smoked heavily during pregnancy -- at least 20 cigarettes per day -- were more than twice as likely as the non-smokers to have a miscarriage.
Seven percent (32) of the 430 women who suffered a miscarriage smoked that amount, versus four percent (36) of the 860 women who delivered a baby.
Previous research has led to estimates that up to eight percent of pregnancies end in miscarriage between six and eight weeks after the woman's last period, but after 10 weeks that rate drops to two percent.
Most miscarriages happen in the first trimester and experts believe that the majority of those are caused by random genetic abnormalities that cannot be prevented. However, certain lifestyle habits have been linked to a relatively increased risk of miscarriage -- including heavy drinking, drug use and, in some studies, smoking.
The current findings do not prove that smoking, itself, was the reason for the increased miscarriage risk seen in the study group. But the researchers were able to account for several other factors, including the women's reported drinking habits and histories of past miscarriages. And the smoking-miscarriage link remained.
Baba's team also found that women who worked during the first trimester were 65 percent more likely to have a miscarriage than those who did not work outside the home.
Of women who suffered a miscarriage, one-third said they'd worked outside the home, compared with 19 percent of those who gave birth.
It's not clear what to make of that finding, according to the researchers. One problem is that they lacked any employment information on a large portion of the study group - 35 percent.
More importantly, they could not divide the women into job types.
Some studies, Baba's team notes, have linked certain jobs with high physical demands or chemical exposures to miscarriage risk. One recent study, for instance, found that women exposed to anesthesia fumes in veterinary centers had a higher-than-average miscarriage risk.
However, the researchers write, they know of no studies outside of /www.reuters.com/places/japan">http://www.reuters.com/places/japan">Japan that have linked employment, as a whole, to an increased miscarriage risk.
More research is needed, they say, to explain the finding.
According to the American College of Obstetricians and Gynecologists, there is no proof that working during pregnancy raises a woman's miscarriage risk.
SOURCE: Human Reproduction, online December 14, 2010.
http://www.reuters.com/article/idUSTRE6BT3VP20101230
Journal: Human Reproduction. (2010) doi: 10.1093/humrep/deq343 First published online: December 14, 2010
Authors: Sachiko Baba, Hiroyuki Noda, Masahiro Nakayama, Masako Waguri, Nobuaki Mitsuda and Hiroyasu Iso
Abstract
BACKGROUND No epidemiological studies have examined risk factors for early spontaneous abortions among Japanese women. In this matched case–control study, we investigated the associations of reproductive, physical and lifestyle characteristics of women and their husbands with early spontaneous abortion <12 weeks of gestation.
METHODS Information was collected through medical records for 430 cases of early spontaneous abortion and 860 controls of term delivery. Two controls were individual-matched to one case according to maternal age (±3 years) and calendar year of events (either early spontaneous abortion or delivery). Multivariable conditional odds ratios (ORs) and 95% confidence interval (CI) were calculated with conditional logistic-regression.
RESULTS The risk of early spontaneous abortions was higher for women with a past history of early spontaneous abortions; OR was 1.98 (95% CI: 1.35, 2.89) for one previous spontaneous abortion, 2.36 (95% CI: 1.47, 3.79) for two, and 8.73 (95% CI: 5.22, 14.62) for three or more. Other factors also influence risk; an OR of 2.39 (95% CI: 1.26, 4.25) was found for women who smoked, and 1.65 (95%CI: 1.17, 2.35) for women working outside the home.
CONCLUSIONS Our finding suggests that for Japanese women, smoking and working may be important public health issue targets for the prevention of early spontaneous abortions.
http://humrep.oxfordjournals.org/content/early/2010/12/13/humrep.deq343
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