Studies that have assessed the risks of different types of infertility have found some evidence that smokers are at particular risk of tubal infertility, in which the underlying problem is thought to involve the function of the fallopian tubes. For example, one study found that women with primary tubal infertility were almost three times as likely to be smokers as were fertile women
Reduced response to fertility treatment
Studies of couples who have used assisted reproduction techniques, such as in vitro fertilisation, have suggested a poorer response to techniques among smokers. In ovarian stimulation, hormones are administered with the aim of increasing egg production. During this treatment, women who smoke have been found to have lower levels of the active form of the sex hormone oestrogen both in their blood and in the ovary during maturation of the egg. Women who smoke tend to produce fewer eggs in response to fertility treatment. The more cigarettes smoked, the fewer eggs produced.Smoking may also reduce the likelihood of fertilisation, implantation and successful pregnancy resulting from assisted reproduction techniques. One recent report found that women who smoked were significantly more likely than non-smokers to suffer early pregnancy loss after embryo transfer.
Recent studies have looked at the effect of male smoking on assisted reproduction techniques. One study of heterosexual couples reported that smoking reduced the success of both in vitro fertilisation (IVF) and intracytoplasmic sperm injection. For example, while 38 per cent of women with non-smoking partners became pregnant during ICSI treatment, the rate fell to just 22 per cent among women whose partners smoked.
Smoking and fertility
It is estimated that around one in six couples in the UK experiences problems in conceiving at some time. Several types of study provide information on the effects of smoking on fertility. Semen analysis can reveal abnormalities. Surveys of pregnant women can investigate the time taken to conceive.Studies of couples can compare those who conceive with those who do not. Finally, investigation of couples having fertility
treatments can help to characterise differences in the quality of egg and sperm, fertilisation, implantation and early loss of embryos.
Smoking reduces fertility in both men and women. The fertility problems observed in smokers may result at least in part from alterations in sex hormone metabolism Other effects may also contribute. Substances present in cigarette smoke have been found to be toxic to the testes and ovaries.
(published with permission in writing from:http://www.bma.org.uk)
