The findings of a new study showed that women who smoked at the start of their first pregnancy were more likely to have a baby born smaller than expected in their second pregnancy compared to non-smokers. This was even the case where they reported quitting by the start of their second pregnancy.
The biological relationship between smoking during pregnancy and a baby's birth weight from the same pregnancy is well established. However, until now there has been limited evidence on the impact of maternal smoking on following pregnancies.
In this study, the researchers found that for women who did not smoke at the start of either pregnancy, there was no extra risk of a Small for Gestational Age (SGA) baby in the second pregnancy compared to non-smokers, even if they smoked between pregnancies.
A mother who smoked ten or more cigarettes a day at the start of both of her first two pregnancies had the highest odds of SGA birth.
Dr. Nisreen Alwan, Associate Professor in Public Health at the University of Southampton, who led the study, said, "It is important to encourage women to quit smoking before pregnancy and to not resume smoking after the baby is born. Resources that support mothers to quit and maintain smoking cessation are needed."