Women and Smoking

The cigarette industry has been marketing tobacco as part of women’s emancipation and opportunity to fulfil the roles set by society. In late 1970’s Finland moved on to the phase where smoking by men and their tobacco-related mortality were decreasing while smoking by women was increasing.

There is a 20 – 25 years’ delay between smoking becoming more common and tobacco-related mortality. Due to this, smoking has not yet had significant effects on women’s overall mortality in Finland.
In Great Britain women’s tobacco-related mortality has been estimated by different disease groups: 12 % of women’s cardiac infarctions and 9 % of cerebral infarctions are linked with smoking. Most women stop smoking for their pregnancy and breastfeeding periods.

On average women smoke less than men, and sporadic smoking is more common among women.

Among smoking women the risk of catching a tobacco-related illness is similar to that of men. It is true that oestrogen hormone protects women against cardiovascular diseases until their middle age. Smoking decreases the amount of oestrogen. The effects on the occurrence of cancer and mortality caused by changes in the frequency of smoking begin to manifest themselves on 10 -15 years’ delay. Chronic obstructive pulmonary disease, which was earlier considered to be a men’s disease, is quickly getting more common among women.

Fertility

Smoking weakens both men’s and women’s fertility. According to an American inquiry-based study women are well aware of the harmful effects that smoking has on respiratory and circulatory systems, but the awareness is scarce of its harmful effects on reproductive health.

Smoking women reach their menopausal age 1.5 – 2 years earlier than non-smokers, which indicates that smoking has a debilitating effect on fertility. There are also some indications that it is a dose-dependent relationship, and that mere exposure to environmental tobacco smoke is weakening fertility.

Smoking also weakens the results of infertility treatments, because it reduces the number of ripened egg cells and increases pregnancy-related complications. There are some signs that if one or both of the parents are smoking, the risk of failure in infertility treatment is 2.4-fold and the risk of miscarriage during the treatment is 3,8-fold. Smoking cessation normalizes the prognosis back to the level of non-smokers.

One should stop smoking three months prior to pregnancy in order to avoid placental complications. It has been estimated that every fourth premature loosening of the placenta would be due to the mother smoking. The risk is 1.5-fold among those who smoke during pregnancy.

Effects during Pregnancy

Smoking and tobacco smoke are a risk for the mother and foetus. Those mothers who have smoked during pregnancy have a greater risk of premature birth, which is always connected with raised foetal mortality rate and risk of complications.

Nearly all toxic substances of tobacco such as carbon monoxide, polycyclic aromatic hydrocarbons, benzene and cyanide can pass through the placental barrier. Smoking women experience more frequent spontaneous abortions. The risk is dose-related: those who smoke fewer than 10 cigarettes have 46 % greater risk and those who smoke more than 20 cigarettes have 61 % greater risk compared to non-smokers.

During smoking numerous chemicals are being absorbed into the blood circulation. From the point of view of foetal growth the essential factor is carbon monoxide. Carbon monoxide displaces the oxygen in red blood cells, causing thus lack of oxygen in the foetus and placenta. Smoking mothers’ newborn babies face an increased risk of being born underweight (on average 255 grams lighter). According to estimates 21 % of cases with newborn babies’ underweight are directly due to mothers’ smoking during pregnancy. The effect of smoking on foetal weight is greater than mother’s length, weight, or number or progress of her prior deliveries.

Low Foetal Weight

Newborn babies of smoking mothers are on average 150 – 300 grams lighter, and the risk of low birth weight is twice as high. Exposure to tobacco smoke during pregnancy leads to the baby’s weight at birth being reduced by 20 -90 grams on average.

Smoking hampers foetal growth by affecting the growth environment. During smoking there is an increase in the amount of carbon monoxide in the blood, and a decrease in the amount of oxygen in the tissues of the mother and foetus. Low birth weight and premature birth are connected with high perinatal mortality (stillbirths and deaths during the first week of life), with developmental problems and certain malformations. Smoking affects the vitamin levels of the organs. During pregnancy, smoking women have lower levels of vitamin B, folate, which is essential for the development of the central nervous system of the foetus.

In research studies smoking has had an indirect connection with the child’s later development. However, because there is not an even prevalence of smoking in different  social classes, the effects on e.g. learning disabilities can be hidden by other factors. Furthermore, low birth weight may predispose to later cardiovascular diseases.

The effects of smoking on the lungs of the developing foetus manifest themselves both indirectly through lung-related problems caused by low birth-weight and premature birth, and possibly also directly though tissues of the lungs. The development of the lungs begins during tenth pregnancy week. Prematurity and low birth weight are themselves a risk for the development of the lungs and respiratory functions. Some studies have revealed that newborn babies of smoking mothers received lower values in pulmonary function measurements.

Changes in Central Nervous System

Smoking damages the developing central nervous system through several biological mechanisms. Such mechanisms are direct neurotoxic effects of tobacco (e.g. lead, nicotine), nicotine-induced changes in the placental blood circulation and consequential lack of oxygen.

Premature birth, low birth weight and small head circumference are connected with increased risk of the child’s cognitive problems at later age. Mother’s smoking has a dose-response relationship with the child’s risk of suffering from learning problems.

Nicotine passes through the placental barrier. When the mother is smoking the nicotine level in the blood of the foetus is higher than that of mother’s. The harmful effects of nicotine on the brain are transmitted through several different mechanisms. Nicotine affects the development of the brain and the formation of nerve synapses by regulating the  (cholinergic and catecholaminergic) systems transmitted by essential neurotransmitters.

Mother’s smoking increases the risk for problems in the baby’s development. The risk has been on average 1,5-fold and has remained so even when obscuring factors have been taken into account such as mother’s education, age, social status and family type. Hyperactivity is more common among those newborn babies whose mothers have been smoking to the end of pregnancy, compared to others. Some of the hyperactivity may be due to the baby’s symptoms of nicotine withdrawal. The effect of smoking on the child’s intelligence is insignificant, but most of the problems that arise at later age pertain to concentration ability, memory and behaviour. Special difficulties have been reported in the learning of language and mathematics.

Women who smoke during pregnancy are on average younger and less educated than non-smokers. Low education and low income level are also risk factors for developmental problems. Smoking is an additional risk, which may be easier to influence directly than income level or education.

Miscarriage

In research studies higher risk for miscarriages has been reported among smokers compared to non-smokers. The risk can even be twice as high. Studies indicate that miscarriage and smoking seem to have a dose-response relationship.

Premature Birth

Several studies suggest a greater risk of premature birth among smokers in comparison with non-smokers.

Central mechanism that links smoking with premature births is the increase of foetal and pregnancy complications in smokers. Many research studies indicate that mother’s active smoking during pregnancy adds the risk for ectopic pregnancies. A distinct causal connection has been found between mother’s active smoking during pregnancy and premature rupture of the foetal membranes. Causality has also been proved to exist between placenta previa, premature loosening of the placenta, risk for pre-eclampsia and smoking.

Cot Death

Mother’s smoking increases the risk for cot death. Tobacco smoke and carbon monoxide probably raise the threshold of the baby’s respiratory centre to react to lack of oxygen by changing position or by screaming.

According to an American study in which more than 2 million babies were  observed until the age of one year, mother’s smoking increased the risk for cot death dose-relatedly.

Researchers estimate that if pregnant women did not smoke or stopped smoking during pregnancy, peri- and postnatal mortality (stillbirths and deaths during the first week of life) would decrease by 10 %.

Breastfeeding and Lactation Problems

Mothers who smoke tend to breastfeed more seldom and for shorter periods than non-smoking mothers. Breast milk from a smoking mother tastes and smells like tobacco. There are not many research studies that have been conducted on the willingness of smoking mothers to breastfeed.

Nicotine reduces the secretion of the hormone needed in lactating (prolactin) from the pituitary gland, which diminishes lactation. At the same time, smoking raises the adrenaline level, which leads to a reduction in the secretion of oxytocin, which is another important hormone for breastfeeding. Smoking hampers the functioning of the mammary gland by cutting down oxygen delivery in the blood, and nicotine by constricting the blood vessels.

Breastfeeding is affected by not only physiological but also psychic and social factors, and their significance is considerable regardless of the mother’s smoking status.

To the baby nicotine causes irritability, increased heartbeat, nausea, diarrhoea and abdominal pains. The effects are dose-related. Infantile colic occurs more often if the mother is breastfeeding and smokes. The baby’s nicotine exposure is also influenced by his exposure to environmental tobacco smoke.

While the mother is smoking, nicotine finds its way quickly from the serum into breast milk, and its level in the breast milk is 3-fold compared to serum. There is a rise also in cadmium level. The urine of babies breastfed by smoking mothers contains tenfold amount of nicotine decay products in comparison with babies who are not breastfed by their smoking mothers. The amount of nicotine is comparable to the amount and frequency of smoking, and mother’s manner of smoking. Also the use of adhesive nicotine patches may lead to high concentrations.

Breastfeeding is beneficial for the baby’s health. If the mother is unable to stop smoking during breastfeeding, smoking should be avoided 2 – 3 hours prior and during the feeding. Furthermore, it should be attended to that the baby is not exposed to smoke. Also, a 2 -3 hours’ abstinence is necessary when using nicotine replacement products.