The relationship between smoking and endometriosis is not very clear. The conclusions of many studies are rather conflicting and opposing.
In a study from Portugal, women who smoked or had stopped smoking, had a smaller chance of getting endometriosis, than non smokers.
A Turkish study found just the opposite from the Portuguese one.
In the USA infertile women with endometriosis were compared to fertile women. With regards to smoking, there was a slightly reduced chance of endometriosis in heavy smokers, who also had started smoking at a young age.
Francesca Bravi, together with collegues from different Italian universities, carried out a meta-analysis of published studies, to clarify the danger of endometriosis in smokers. The study was published in the prestigious British Medical Journal(BMJ) in 2014. A total of 1758 articles were reviewed, of which 38 met the inclusion criteria for this new analysis. The new study included 13.129 women with endometriosis. For study purposes, the women were separated into groups of never smokers, smokers and those who had stopped smoking, as well as classifying them as light or heavy smokers.
It is well known that endometriosis is dependent on oestrogen, which is the female sexual hormone, regulating the menstrual cycle.
How can smoking affect the development of endometriosis?
The answer lies in the effect smoking has on the production of oestrogen as well as on inflammatory compounds. Smoking reduces the production of oestrogen and progesterone and increases the secretion of inflammatory substances, not only in the lungs, but in all body tissues. Both of which are mechanisms that influence the development and expansion of endometriosis.
The present study did not prove any relationship between smoking and endometriosis.
Conclusion: Smoking does neither stop nor cause the appearance of endometriosis.
F. Bravi et al.,BMJ Open 2014:4(12) e006325
Aban M, Ertunc D, Tok EC et al. Modulating interaction of glutathione-S-transferase polymorphisms with smoking in endometriosis. J Reprod Med 2007;52:715–21. [PubMed]