Heavily Smoking Leads to Unsuccessful In-Vitro Fertilization

A recent study found that negative effects of heavy smoking extend as much as to come to affect and cut chances of in-vitro fertilization. The research carried out by a team of scientists at the IVI Clinic in Lisbon showed that women who smoke more than 20 cigarettes daily have less chances of becoming pregnant even when resorting to donated-eggs method than their peers who smoke moderately or did not took up the bad habit at all.

Previous studies have also shown that heavy smoking affects the ovarian tissue, but nothing was known until now about the effects of smoking on the uterine tissue. However, Spanish and Portuguese scientists made it clear in their report published in the Human Reproduction Journal that heavy smoking does not have negative effects on a woman's ovarian tissue, but also on the lining of her womb. The side effects of heavy smoking on a woman's womb tissue work by damaging it and making it more difficult for the uterine tissue to be receptive to and 'accept' the imported and already fertilized egg.

Lead researcher of the study Dr Sérgio Soares stated: "Cigarette smoking negatively affects pregnancy probability even when the eggs come from a non-smoker. This is the first time an effect of tobacco consumption has been demonstrated on the uterus. The fact that we see this result in a situation in which the oocytes (eggs) were donated by other women demonstrates that cigarette smoking negatively affects the receptiveness of the uterus independently of its effect on ovarian function."

The study was conducted on 44 women who smoked more than 10 cigarettes daily and 785 women who were occasional smokers or did not smoke at all. All the women in the study received in-vitro fertilization and were married to non-smokers. Overall results of the study showed that more than half (52.2%) of the women in the non- or light-smoking group became pregnant after having a fertilized egg implanted in their uterus.

On the other hand, heavy smoking women had a significantly lower rate of pregnancy, with only 34.1% of them succeeding in becoming pregnant. The findings also showed that even if the in-vitro fertilization succeeds in a heavy smoker, the woman is very likely not to achieve a successful pregnancy. However, surprisingly, the results of the same study showed that heavy smokers have increased chances of multiple births as compared to their peers who do not smoke or puff a cigarette only occasionally.

Dr. Soares concluded: "It means that we should now be telling patients, if they are heavy smokers, that even if fertilization takes place they have less chance of achieving a successful pregnancy, whether they are trying to conceive naturally or through IVF, and particularly with donated (eggs). We should also warn them of the risks of multiple births, as multiple births are less safe for mothers or babies."