Pregnancy Week by Week

Smoking During Pregnancy

Smoking in women is growing especially, in women of reproductive age. At the age of 18 years one in two women smoke and statistics also show that 50% of women using hormonal contraception in developed countries smoke. It is considered that in the European countries, 37% of pregnant women have been smoking before pregnancy and also 19-20% of pregnant women smoke throughout pregnancy. The passive smoking phenomenon (which is also harmful) is difficult to quantify.

Smoking is one of the most widespread harmful habits. More and more studies tend to include cigarettes among addictive drugs that affect health.

How does smoking affect pregnancy?

Smoking is one of the leading causes of preventable pregnancy complications. Basically, a pregnant woman should stop smoking and thus avoid many risks. There are specific problems that can occur in babies if mothers smoke. Therefore, it is very important that a pregnant woman should quit smoking as soon as she learns that she is pregnant.

Smoking affects pregnancy by two components of the cigarette smoke: nicotine and carbon monoxide. Both cross the barrier represented by the placenta without any problems and can be found in fetal blood at higher concentrations than in maternal blood.

Children of smoking mothers have lower birth weight and therefore, are less likely to get infections and other illnesses. Also, smoking increases the risk of premature birth. A thickening of the placenta was found in smokers, with an increased risk of placenta previa. A risk of miscarriage also appears in smoking women.

Quitting smoking would be the best thing to do before getting pregnant or soon after. Studies show that the risk of prematurity and fetal hypotrophy remains high (though not at the same level) in mothers who quit smoking after the first trimester of pregnancy.

Cigarette smoke contains over 4,000 substances, of which about 30 were identified as being harmful, the rest being still in research. Cyanides affect the metabolism of vitamins B, C and calcium. Carbon monoxide blocks oxygen transport by hemoglobin and oxygen to cells. Lack of oxygenation causes thickening of the placenta so that fetal tissue, finds it difficult to develop. At birth, the child will have a low weight, below average.

Nicotine in small doses increases the mother's mental activity and alertness, and in large doses has the opposite effect. Moreover, it produces similar cardiovascular effects of stress, by stimulating the release of stress mediators. They reduce the blood supply to internal organs and the placenta, leading to delayed fetal development.

Dependence should be evaluated

A pregnant woman who smokes should be questioned thoroughly on history of smoking and the clinical symptoms of her smoking (cough, difficulty breathing, sputum).

Physical and psychological tobacco dependence should also be assessed and the concentration of carbon monoxide in her blood determined. Depending on the data obtained it is advisable to establish a therapeutic plan (psychological support, behavioral therapy and group sessions).

In the case of a heavy smoker, a nicotine substitute associated with psychological support is recommended. Pregnant women are also using a patch which releases nicotine transversally (having a 16 hours or 24 hours effect), gum or pills.