According to a team of European researchers, it has long been known that smoking affects female fertility. However this is believed to be the first study to show that the habit actually damages the lining of the uterus, making it less receptive and reducing the chances that an embryo will implant itself in the wall of the womb.
The study looked at the impact of women who had received donated oocytes – the cells from which eggs develop. According to the researchers, this situation allows the most objective assessment of the role of the uterus in the outcome of IVF (in vitro fertilisation).
They looked at IVF treatments carried out at a clinic between early 2002 and June 2005 – 741 of these were in non-heavy smokers (less than 10 cigarettes a day) and 44 were in heavy smokers (over 10 a day). None of the women’s partners were smokers and none of the oocyte donors were heavy smokers.
The researchers found that ‘heavy smokers have a much lower chance of achieving pregnancy’. However in those who did become pregnant, the multiple pregnancy rate was higher.
“The fact that we see this result in a situation in which the oocytes were donated by other women demonstrates that cigarette smoking negatively affects the receptiveness of the uterus independently of its effect on ovarian function and this is a new finding”, explained lead researcher, Dr Sergio Soares.
He suggests that heavy smoking ‘disrupts the stability of cells in the lining of the uterus differently in some women or triggers a response in the embryo itself’.
“This could result in a reduced general pregnancy rate overall, but an increased chance of multiple pregnancy in those who do become pregnant”, he explained.
He added that while more research is needed in this area, patients who are heavy smokers should be told that even if fertilisation takes place, they have ‘less chance of achieving a successful pregnancy, whether they are trying to conceive naturally or through IVF’.
Posted by : Goral Gandhi, MSc,
Rotunda – Center for Human Reproduction (Pvt) Ltd