Female fertility passive smoking as harmful as active smoking

Passive smoking is also harmful as active smoking to female fertility, according to a Canadian study published in the journal "Human Reproduction", suggesting a reduction in the chances of success of in vitro fertilization (IVF) with embryo transfer.
The effects of active smoking on female fertility have already been confirmed, but the effects of passive smoking have remained unknown until now, say Dr. Michael S. Neal at McMaster University in Hamilton (Ontario) and colleagues.

Researchers have therefore evaluated from 225 women candidates for conventional IVF or micro-sperm injection (ICSI), categorized as non-smokers, smokers or passive smokers if their spouse was.

No difference was observed in embryo quality between the three groups.

However, while the pregnancy rate was 48% among non-smokers, it was only 19% in smokers and 20% among women exposed to passive smoking.

The implantation rate, defined as the number of gestational sacs with cardiac activity at 7 weeks divided by the number of embryos transferred was 25% among non-smokers, against about 12% in the active or passive smokers.

These results from a retrospective analysis based on self-reporting of smoking habits on must be confirmed by a prospective study with objective measures of exposure to cigarette smoke and an evaluation of the dose-response relationship, said Professor Warren Foster, of McMaster University, in a news magazine.

However, "these results already deserve to warn women to reduce or, if possible, eliminate their exposure to smoking, especially if they are trying to conceive a child," he says.

The researchers plan to launch a prospective study on this subject if they get funding, and seek potential collaborators.

They are also trying to determine why no difference was observed in the appearance and development of embryos before transfer in utero between the three groups, while a decrease in the ability of embryos to implant and / or maintain a pregnancy for active or passive smoking was the main highlight.

It is possible, says Dr. Neal, that cigarette smoke has compromised the competence of the oocyte, by altering the proliferation of granulosa cells in the follicle and the production of aromatase, an enzyme involved in estrogen production but lethal results were not apparent until a later stage of embryonic development.