Impact of smoking while pregnant worse than thought according to new Cambridge Uni study
Women who smoke during pregnancy are 2.6 times more likely to give birth prematurely compared with non-smokers
A new study from the University of Cambridge has found the risk of premature births from smoking while pregnant is twice as likely as previously thought.
The study also found smoking meant the baby was four times more likely to be small for its gestational age, putting it at risk of potentially serious complications including breathing difficulties and infections.
There was no evidence caffeine intake was linked to negative outcomes.
Professor Gordon Smith, head of the department of obstetrics and gynaecology at the University of Cambridge, said: “We’ve known for a long time that smoking during pregnancy is not good for the baby, but our study shows that it’s potentially much worse than previously thought.
“It puts the baby at risk of potentially serious complications from growing too slowly in the womb or from being born too soon.
“We hope this knowledge will help encourage pregnant mums and women planning pregnancy to access smoking-cessation services.
“Pregnancy is a key time when women quit and if they can remain tobacco free after the birth there are lifelong benefits for them and their child.”
"It puts the baby at risk of potentially serious complications from growing too slowly in the womb or from being born too soon"
The NHS recommends that women who are pregnant should stop smoking and limit their caffeine intake because of the risk of complications to the baby.
When the toxins from smoke travel through the bloodstream to the baby, it struggles for oxygen.
Researchers at Cambridge and the Rosie Hospital, part of Cambridge University Hospitals NHS Foundation Trust, recruited more than 4,200 women who attended the hospital between 2008 and 2012 as part of the Pregnancy Outcome Prediction (POP) study.
The team analysed blood samples taken from a group of these women four times during their pregnancies.
To assess exposure to cigarette smoke, the team looked at levels of cotinine, which can be detected in blood, urine and saliva.
Only two out of three women with detectable levels of cotinine in every blood sample were self-reported smokers, showing that this measure is a more objective way of assessing smoking behaviour, researchers say.
A total of 914 women were included in the smoking analysis.
The study, published in the International Journal of Epidemiology, found that compared with those without smoke exposure while pregnant, those with consistent exposure were 2.6 times more likely to experience spontaneous preterm birth.
According to the researchers, this is more than double the previous estimate of 1.27 from an analysis of multiple studies.
They were also 4.1 times as likely to experience foetal growth restriction.