By: 22 April 2020
Smoking during first trimester still puts baby at risk

Mothers who quit smoking during their first trimester do not significantly reduce the risk of their babies being born with abnormal body proportions, a study recently published in BMJ Open has found.

Dr Isabell Rumrich, of the University of Eastern Finland, and other scientists studied 1.38 million children born without congenital anomalies between 1 January 1991 and 31 December 2016.

They analysed the effect of maternal smoking on body size and body proportions of newborns when the mother had smoked only during the first trimester, in comparison with continued smoking after the first trimester. They also evaluated how growth restriction associated with maternal smoking contributes to changes in body proportions.

Babies whose mothers continued smoking after the first trimester had a higher risk of being born with high ponderal index, low brain-to-body ratio and high head-to-length ratio (absolute risks of 22%, 10% and 19%, respectively).

The effects were slightly lower when a mother had quit smoking it during the first trimester.

Rumrich and her colleagues concluded: “Maternal smoking, independent of smoking duration during pregnancy, was associated with abnormal body proportions resulting from larger reduction of length and head circumference in comparison to weight. The effects of having quit smoking during the first trimester and having continued smoking after the first trimester were similar, suggesting the importance of early pregnancy as a sensitive exposure window.”

Source: BMJ Open