Smoking cuts IVF success rate

Last published / updated April 8 2005.

In a study about to be published in the journal Human Reproduction, infertile women who smoke were found to have lower pregnancy rates and higher miscarriage rates during treatment with in vitro fertilization – IVF.

Smoking reduced IVF pregnancy rates

Danish researchers looked at 8,457 women aged 20 to 40 who had had in vitro fertilization treatment. The patients were divided into four groups, depending on the cause of each couple’s fertility problems; male fertility disorder, fallopian tube problems, other clinical explanations – such as polycystic ovaries or endometriosis, or unexplained fertility problems.

Overall, the live birth rate for smokers was 28% lower than non-smokers. Among women with unexplained infertility, the live birth rate was a third lower for smokers, at 13% compared to 20% for non-smokers. This is the same effects as would be seen for women who were ten years older. In other words, a 35 year old woman who smokes would have the pregnancy rate a 45 year old.

Smokers produced the same number of eggs as non-smokers. In this study, they actually had more embryos transferred. Despite the higher number of embryos, they still had lower pregnancy rates. This implies that smoking is damaging egg and/or embryo quality.

Smoking increased IVF miscarriage rates

Smokers also had a significantly higher miscarriage rate. The miscarriage rate for smokers was 21.4% compared to 16.4% for non-smokers.

Discussion

Overall, the chance for a livebirth in smokers is much lower due to the “double whammy” of lower pregnancy rates and higher miscarriage rates.

We have had a considerable amount of data for some time that smoking causes infertility. what is interesting about this study is that it quantifies the effect that patients can readily understand.

Most patients are aware that fertility declines with age so knowing that smoking subtracts 10 years from your reproductive potential is a powerful indicator of its effect.

One limitation of this study is that they did not quantify the amount of smoking and also relate it to pregnancy rates.