IVF: smoking, a detrimental effect on uterine receptivity

Smoking, especially at high doses, negatively affects the responsiveness of the embryo, reducing the chances of implementing it, reveal the results of a study published on the website of the journal "Human Reproduction".
The negative impact of smoking on ovarian function is fairly well established, but the hypothesis of a concomitant effect on the uterus has not been proven directly, recall Dr. Sergio Soares, Instituto Valenciano de infertilidad ( IVI) in Lisbon, Valencia and colleagues.

To clarify this point, they analyzed retrospectively the first cycles of in vitro fertilization (IVF) made from donated oocytes in 741 non-smokers or light smokers (less than ten cigarettes per day) and in 44 heavy smokers (more ten cigarettes per day).

Non-smokers and light smokers were included in the same group as previous studies have shown that light smoking exerts no impact on the outcome of IVF. None of the spouses was smoking recipient and donor were either nonsmokers or light smokers.

The pregnancy rate among non-smokers or light smokers recipients was significantly higher than that observed in heavy smokers (52.2% against 34.1%).

"The fact that this new result is observed in a situation in which the oocytes were donated by other women demonstrates that smoking negatively affects the receptivity of the uterus independently of its effect on ovarian function," says Dr. Soares in a statement of the journal "Human Reproduction".

Paradoxically, in heavy smokers managing to be pregnant, the multiple pregnancy rate appeared two times higher than in the other group (60% against 31%).

"We already know that there is a paradoxical dose-dependent effect of nicotine on ovarian tissue. Perhaps the same effect there place in the uterine tissue," suggests Dr. Soares.

These results should be confirmed in larger studies and it would be also interesting to study the differences in gene expression in the endometrium of heavy smokers who fail to get pregnant and those with twins, says researcher .