Smoking in pregnancy—effects on birth weight and on cyanide and thiocyanate levels in mother and baby. — PubMed


A total of 45 expectant mothers (20 smokers and 25 non-smokers) and their babies was studied and, after 14 smokers and 14 non-smokers had been closely matched for age, height, parity and social class, significant differences were observed between smokers and non-smokers in the birth weights of the babies and in cyanide and thiocyanate levels in maternal blood and urine.

OBJECTIVE: To determine whether maternal smoking during pregnancy causes impairment in growth after birth.

DESIGN: Longitudinal study.

SETTING: Six medical university centres of six towns of north, central, and south Italy.

SUBJECTS: 12,987 babies (10,238 born from non-smoking mothers, 2276 from mothers smoking one to nine cigarettes a day, and 473 from mothers smoking {amp}gt; or = 10 cigarettes a day) entered the study.

MAIN OUTCOME MEASURES: Difference in weight gain between children born to smoking mothers and those born to non-smoking mothers. Weight was measured at birth and at 3 and 6 months of age. Maternal smoking habit was derived from interview on third or fourth day after delivery.

RESULTS: Compared with children born to mothers who did not smoke during pregnancy, the birth weights of children born to mothers who smoked up to nine cigarettes a day were 88 g (girls) and 107 g (boys) lower;

in children born to mothers who smoked {amp}gt; or = 10 cigarettes a day weights were 168 g and 247 g lower. At six months of age for the first group the mean weight for girls was 9 g (95% confidence interval -47 g to 65 g) higher and for boys 64 g (-118 g to -10 g) lower than that of children born to mothers who did not smoke.

CONCLUSIONS: The deficits of weight at birth in children born to mothers who smoked during pregnancy are overcome by 6 months of age. These deficits are probably not permanent when smoking habit during pregnancy is not associated with other unfavourable variables (such as lower socioeconomic class).

Babies to mothers who smoke weigh 200 grams less at birth



IMAGE: The babies of women who smoke during pregnancy are between 180 and 230 grams lighter than babies of women who do not smoke.
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Credit: SINC

Smoking during pregnancy has widely documented health repercussions both for mother and baby. A study at the University of Zaragoza on 1216 newly born babies confirms that those born to mothers who smoke weigh and measure less.

A new study lead by the University of Zaragoza evaluates the differences in body composition and proportional distribution of body mass between babies born to mothers who have or have not smoked during pregnancy.

Published in the Early Human Development journal, the study reveals that children of woman who did not smoke during pregnancy weigh and measure more. Their corporal dimensions are also significantly higher compared to the children of mothers who did smoke during pregnancy. But, this is not the same as body weight index (the relationship between height and cubic weight).

In fact, the results highlight that mothers who smoke during pregnancy give birth to babies that are between 180 and 230 grams thinner than the offspring of mothers who do not smoke. In other words, this constitutes an average of 216 grams.

Furthermore, subcutaneous skinfolds, which show the amount of fat, are lower in children born of mothers who smoked. In this case however, differences were not as great as with body size. On the contrary, the authors of the study did not find any correlation between anthropometric measurements and the number of cigarettes smoked per day during pregnancy.

«Given the scarce bibliography on the subject, we had to assess the impact of tobacco on the body composition of babies born to mothers who smoked during pregnancy,» as explained to SINC by Gerardo Rodríguez, lead author of the study.

For this purpose, the experts analysed the newly born full term babies with a gestational age of at least 37 weeks of 1216 Caucasian mothers (22.1% of whom smoked an average of almost eight cigarettes per day) in the University Clinical Hospital of Lozano Blesa in Zaragoza. The children of those mothers who had admitted to consuming alcohol or taking illegal drugs during pregnancy were excluded from the study.

«Tobacco consumption during pregnancy can cause a generalised reduction in the majority of parameters as a result of a decrease in foetal growth. Newly born babies to mothers who smoked during pregnancy are smaller and have less subcutaneous fat compartments,» concludes Rodríguez.

Chronology of passive smoking

The first indication of the health consequences of ‘passive smoking’ arose at the beginning of the 1970’s with the publication of works that verified the risk of inhaling a ‘environmental tobacco smoke’ by a non-smoker with respiratory or heart-related illness and by children whose parents were smokers.

In 1981 the British Medical Journal published a study by the epidemiologist Hirayama, who for the first time established that the passive smoker has an increased risk of developing lung cancer. For 14 years, Hirayama had studied a sample population of non-smoking women who lived with smoking families. During the following years, works were published that related this with other pathologies.

The environmental tobacco smoke is a mixture of the smoke exhaled by the smoker (main current) and the smoke of the cigarette through spontaneous combustion (secondary current). The main current comes from a combustion that has a higher oxygen content than that is filtered throughout the cigarette itself.

At present there is unanimity that «passive smoking» has adverse effects on the health. The scientific community has no doubt that in adults it causes an increased risk of lung cancer, cardiovascular disease and chronic obstructive pulmonary disease (COPD).



Samper MP, Jiménez-Muro A, Nerín I, Marqueta A, Ventura P, Rodríguez G. «Maternal active smoking and newborn body composition». Early Human Development 88 (2012) 141-145.


Gerardo Rodríguez

Universidad de Zaragoza

Tel.: 34 928 45 34 02 / 34 76


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How Does Smoking Affect Fertility?

Most people know that smoking causes cancer and other major health problems. And smoking while you’re pregnant can cause serious problems, too. Your baby could be born too early, have a birth defect, or die from sudden infant death syndrome (SIDS).

It’s best to quit smoking before you get pregnant. But if you’re already pregnant, quitting can still help protect you and your baby from health problems. It’s never too late to quit smoking.2

If you smoked and had a healthy pregnancy in the past, there’s no guarantee that your next pregnancy will be healthy. When you smoke during pregnancy, you put your health and your baby’s health at risk.3

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Smoking can cause fertility problems for you or your partner. Women who smoke have more trouble getting pregnant than women who don’t smoke. In men, smoking can damage sperm and contribute to impotence (erectile dysfunction, or ED).

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