Scans taken of developing fetuses show the effects of tobacco smoking on the developing baby while still in the womb. The study showed that consumption of tobacco products can significantly impact the growth of fetuses.

Lancaster University researchers, along with colleagues from Durham University, used ultrasound to study how smoking affects the development of babies over time. Fetuses of mothers who smoke were found to exhibit mouth movements and touch their faces more often than those seen within non-smoking mothers.

These behaviors, often associated with fetal developmental delays, were dramatically higher in fetuses of tobacco-consuming mothers. The study noted that mouth movements declined 1.5 percent per week in fetuses of tobacco users, compared to the normal rate of three percent. At 30 weeks, mouth movements were 58 percent more frequent if mothers smoked than if they did not.

"Normally as the fetus matures, they show more complex movements, and also fewer movements. The frequency of movements should slow as the fetus grows older, so these images indicate that there might be some sort of delay in maturation," Nadja Reissland, an associate professor of psychology at Durham University, said.

A total of 20 fetuses were observed in the study, utilizing 80 4D scans of developing fetuses between 24 and 36 weeks of development. While four mothers in the study consumed an average of 14 cigarettes a day, the other 16 were non-smokers.

The reason for this developmental delay is uncertain, but it is possible that nicotine could bind to receptors in the brains of fetuses, leading to premature cell death. Babies of mothers who smoke were not found to have higher rates of premature deliveries, or to have lower birth rates, than those from non-smoking women.

"Technology means we can now see what was previously hidden, revealing how smoking affects the development of the fetus in ways we did not realise. This is yet further evidence of the negative effects of smoking in pregnancy,"  Brian Francis of Lancaster University said.

Previous studies have shown that depression and stress can have a profound effect on fetal development, but this new study suggests that tobacco use can also affect the developing fetus. Although the sample size is small, this new study is consistent with most previous research.  

Future research could examine how smoking can interact with stress, depression and other factors during the formation of fetuses. Researchers could also examine how fathers who smoke could alter fetal development.

Study of developing fetuses in mothers who smoke compared to those who do not consume tobacco was published in the journal Acta Paediatrica.

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