As well as being at risk of suffering the health effects of smoking described above, women are at risk of developing a number of sex-specific problems due to smoking.
The risk of heart attack, stroke and other cardiovascular diseases in women is increased by approximately tenfold if they both smoke and use oral contraceptives.(97)
The contraceptive pill is one of the most common ways in which Australian women control their fertility. In 1989 around 25% of women over the age of 20 were current pill users, with highest levels of usage occurring in women aged between 20-24, of whom 56% were current users.(98) The fact that this is also the age group with the highest smoking prevalence(29) gives special cause for concern.
A recent survey in New South Wales found that use of the oral contraceptive pill was associated with higher rates of smoking, 33% of women on the contraceptive pill smoked compared with 26% of those not on the pill. These smokers had not made greater quit attempts than other smokers in the study, despite being at greater risk from their behaviour.(99)
Several studies have found that women who smoke have decreased fertility. Of these, one study has found that smokers have about 72% of the fertility of non-smokers and are 3.4 times more likely to take more than a year to conceive than non-smokers, all other factors being equal.(100) It has also been shown that female smokers experience a reduced rate of fertility once contraceptive measures have ceased to be taken.(97,101) Studies are increasingly pointing towards a decreased ovulatory response in smokers, and that actual fertilisation and implantation of the zygote may be impaired in smokers.(97)
Research from Queensland has shown that smokers enrolled in IVF-ET (in vitro fertilisation and embryo transfer) and GIFT (gamete intrafallopian transfer) programs have a poorer outcome than non-smokers. Smokers produced fewer oocytes (immature eggs), had a pregnancy rate less than half that of non-smokers, and those smokers attaining a pregnancy had a markedly elevated risk of miscarriage. The authors conclude that the 'far greater chances of success for non-smokers justify vigorous attempts to convince [infertile couples] to stop smoking well before embarking upon assisted reproduction programs.'(102) Similar conclusions have emerged from international research.(103,104)
Smokers experience a greater prevalence of secondary amenorrhea (absence of menstruation), and irregularity of periods. Smokers are also more likely to experience unusual vaginal discharge or bleeding .(97) Smoking causes women to reach natural menopause one to two years earlier than non-smokers or ex-smokers.(2) This may be due to a toxic effect on ovaries caused by smoke exposure,(97) or to the significantly lower levels of oestrogens in smokers noted in many studies.(105)
Recent Australian research has shown cigarette smoking contributes to osteoporosis, an increase in bone fragility that accompanies aging.(106) Smoking reduces bone density, possibly through its effects on oestrogens. The study estimates that women who smoke 20 cigarettes a day through adulthood will have reduced their bone density by around 5 to 10% by the time they reach menopause, compared to non-smokers. This deficit in bone density is enough to increase the risk of fracture.
Women who smoke cigarettes have a greater risk of developing cancers of the cervix and vulvar. For cervical cancer the relationship appears to be dose-responsive, with one study finding an 80% increased risk of developing the cancer among heavy smokers.(40) It is estimated that 19% of cervical cancer and 40% of vulvar cancer is caused by smoking.(4)
For further information on women's health and smoking, see Section 3.8 below, and Chapters 4 and 16.