Smoking Cessation During the 1st Trimester of Pregnancy Still Puts the Baby at Risk

Maternal smoking, independent of smoking duration during pregnancy, was linked to abnormal body proportions resulting from a larger reduction of length and head circumference in comparison to weight, reports a new study. The findings of the study are published in the journal BMJ Open. The study looked at 1.4 million mother-child pairs in Finland, analyzing the effect of maternal smoking on newborns' body size and body proportions when the mother had smoked only during the 1st trimester as opposed to continued smoking.

Tobacco smoke contains thousands of chemicals, which can cross the placenta and enter fetal circulation. Among them, nicotine has a multitude of adverse effects on the development of organs, including the brain. Other well-known toxic chemicals in tobacco smoke include carbon monoxide, which can interfere with the unborn child's oxygen supply.

"Smoking during pregnancy is relatively common. In this study, 84.5% were non-smokers, and 3.5% quit smoking during the 1st trimester, but 12% continued to smoke after the 1st trimester," Researcher Isabell Rumrich from the University of Eastern Finland says.

The study showed that maternal smoking is associated with a stronger reduction in body length and head circumference than in birth weight, leading to changed body proportions. The effects on body proportions of having quit smoking during the 1st trimester or having continued smoking after the 1st trimester were similar, stressing the importance of early pregnancy as a sensitive exposure window. Among the newborns exposed to maternal smoking only during the 1st trimester, all three measurements of body size (birth weight, body length, and head circumference) showed signs of growth restriction. In addition, their body proportions were abnormal.

Furthermore, the study suggests a limited potential to repair fetal damage induced in early pregnancy. Maternal smoking can have an effect on cell proliferation during organogenesis in early prenatal development. Insults during this period have been shown to persist throughout life.

"The most important finding of our study is that although quitting smoking in the 1st trimester reduces the risk of low birth weight, brain size and body length in relation to body weight seem not to catch up. This stresses the importance of quitting smoking already before pregnancy since even smoking only during early pregnancy can have devastating effects on the long term health of the unborn child," Rumrich notes.

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Source-Eurekalert