Approximately 30 per cent of women who smoke in Britain continue to smoke during pregnancy. Cigarettes affect the mothers’ circulation, which in turn will affect the baby. The baby in the womb is totally relying on mother to supply oxygen, nourish and filter out any dangerous chemicals.
o ” The placenta (afterbirth) is the lifeline between mother and baby. When a pregnant woman smokes, oxygen in her blood is replaced by carbon monoxide. Carbon monoxide is a poisonous gas, which robs muscles, brain and body tissues of oxygen making the baby’s heart work harder. If the baby is deprived of oxygen it will suffer from its effects, which is known as hypoxia. The affect of hypoxia happens over a long period of time. The most immediate affect for the baby is his/her movements inside the womb slow down and heart rate speeds up as the baby tries to get more oxygen. There is a reduction in baby movements for up to thirty minutes after the mother has smoked a single cigarette.
o ” The placenta supplies the baby with nutrients; smoking increases the chance that the baby will be born smaller than expected. (Low Birth Weight Baby). Research suggests that some women see a low birth weight baby as an advantage, however there is so much evidence to the contrary. If the baby is smaller at birth it will continue to be smaller throughout its subsequent development. Low birth weight babies are more likely to need intensive care.
o ” The placenta acts as a barrier/filter for certain substances. Unfortunately it cannot keep all of them away and many get through. Nicotine, carbon monoxide, and other chemicals in tobacco smoke are passed on to the baby. There are 4000 chemical in cigarettes of which there are more than 30 known carcinogens. A German study showed traces of NNK, (nicotine-derived nitrosaminoketone) which is one of the strongest cancer causing agents found in tobacco products. It was detected in 22 of 31 newborns of mothers who smoked during pregnancy.
Effects of Nicotine
Nicotine travels through the bloodstream to the brain, and then is delivered to the rest of the body.
80 % of nicotine is broken down to cotinine by enzymes in the liver. A build up of cotinine can act on the womb causing it to contract, or go into labour. Many chemicals, including nicotine, can readily move from the mother’s bloodstream into the foetal blood supply. (This is why physicians are so cautious about what over-the-counter or prescription drugs women take in pregnancy.) If you smoke while pregnant, your child will be exposed to almost the same level of nicotine as you. That means that once he or she is born and is no longer getting nicotine intravenously, the symptoms of nicotine withdrawal will likely set in.
Clinical studies have reported that nicotine concentrations in the placenta, amniotic fluid and foetal serum were consistently higher than maternal serum values when measured at various stages throughout pregnancy
Nicotine alters a smoker’s blood pressure, heart rate, and even their metabolism. Nicotine moves right into the lining of small blood vessels causing them to narrow thus reducing the blood flow to the womb and subsequently to the baby. Nicotine can inhibit the production of prostacyclin, a potent vasodilator and inhibitor of platelet aggregation, in arteries. Studies have shown that nicotine increases uterine vascular resistance and reduces uterine blood flow, possibly by an action on catecholamine release. Smoking acutely and chronically reduces placental blood flow, presumably through an effect of nicotine.
There is, evidence that nicotine impairs foetal growth and can lead to an increased risk of spontaneous abortion and premature delivery. A likely cause of foetal growth retardation is induction of foetal ischaemia (reduced blood supply) and hypoxia (lack of oxygen) as a result of the effect of nicotine on the placental circulation.
Nicotine from cigarettes or replacement therapy has potential adverse effects on human health.
Over 8 million women smoke in the UK. Research amongst female smokers shows that 74% would like to stop smoking but despite these attempts most women continue to be dependent on nicotine and experience difficulty in overcoming their addiction to the drug.
Pregnant women who smoke are often highly motivated to quit, especially during early pregnancy, but many continue to smoke. Smoking amongst expectant mothers in the UK is surprisingly high at 23% and only 3% of people stop smoking successfully when relying solely on willpower.
There are increased risks in pregnancy when the mother smokes. The risk of miscarriage is 27% higher in smokers. Perinatal mortality (defined as still-birth or death of an infant within the first week of life) is increased by about one-third in babies of smokers. The risk of a low birth weight baby (200gramas 7oz) is three times higher. Furthermore, the more cigarettes a woman smokes during pregnancy, the greater the probable reduction in birth weight.
Recent research suggests that cigarettes can reduce the flow of blood in the placenta, which limits the amount of nutrients that reach the foetus. There is a 35% increase in cot deaths associated with smoking in pregnancy. Maternal smoking is associated with a higher risk of children’ s cancers. Infants of parents who smoke are twice as likely to suffer from serious respiratory infection than the children of non-smokers. Smoking during pregnancy can also increase the risk of asthma in young children.
Maternal smoking in pregnancy has been associated with behaviour and attention deficit disorders. Mothers who smoked more than ½ a pack of cigarettes were significantly more likely to have an offspring with conduct disorder. Substance abuse is higher among children of mothers who smoked in pregnancy and also impaired child-rearing behaviour. Smoking in pregnancy may also have implications for the long-term physical growth and intellectual development of the child. It has been associated with a reduced height in children of smoking mothers as compared with non-smoking mothers, with lower attainments in reading and mathematics up to age 16 and even with the highest qualification achieved by the age of 23.
On average, smokers have more complications of pregnancy and labour, which can include bleeding during pregnancy, premature detachment of the placenta and premature rupture of the membranes. Some studies have also revealed a link between smoking and ectopic pregnancy and congenital defects in the offspring of smokers. Women are more likely to experience vomiting, urinary infections, thrush, to feel unwell and have more hospital admissions. There is also evidence that smoking interferes with women’s hormonal balance during pregnancy and that this may have long-term consequences on the reproductive organs of her children.
In December 1998, the UK government set a target to reduce the percentage of women who smoke during pregnancy from 23% to 15% by the year 2010; with a fall to 18% by the year 2005. This will mean approximately 55,000 fewer women in England who smoke during pregnancy. This target has not yet been achieved.
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