A recent study conducted by researchers from the University of Cambridge has unveiled concerning findings regarding the effects of smoking during pregnancy. While some tea and coffee consumption appears to have no detrimental effects on babies, the study indicates that smoking is far more harmful than previously believed.
The National Health Service (NHS) advises pregnant women to limit their caffeine intake to no more than 200mg a day, roughly equivalent to two cups of instant coffee or tea. Furthermore, they strongly recommend quitting smoking due to the known associations between excessive caffeine consumption and smoking with an increased risk of pregnancy complications, premature birth, and fetal growth restriction.
However, the research by Cambridge academics has challenged previous assumptions. The study found no evidence to suggest that above-average caffeine consumption during pregnancy was linked to preterm birth or having smaller babies. Instead, the research revealed a stark contrast: women who smoked while pregnant were nearly three times more likely to give birth prematurely compared to non-smokers, more than double the previous estimate. Additionally, babies born to mothers who smoked were four times more likely to be small for their gestational age, exposing them to serious complications such as respiratory difficulties and infections.
These findings coincide with another study conducted by the University of Essex, which discovered that a pregnant woman or her partner losing their job was associated with an increased risk of miscarriage or stillbirth. The study revealed a doubling in the likelihood of a pregnancy ending in a miscarriage or stillbirth following a job loss.
Previous research on the relationship between smoking, caffeine consumption, and adverse pregnancy outcomes relied primarily on self-reported data, often collected at a single point during pregnancy, which may not be entirely reliable.
In contrast, the recent study, published in the International Journal of Epidemiology, analyzed metabolites from smoking (cotinine) and caffeine (paraxanthine) present in the blood samples of over 900 women who participated in the Pregnancy Outcome Prediction study from 2008 to 2012. Researchers assessed the levels of cotinine and paraxanthine at various stages of pregnancy (12, 20, 28, and 36 weeks) and categorized the women’s exposure to smoking and caffeine accordingly.
Professor Gordon Smith, the head of the department of obstetrics and gynecology at the University of Cambridge, emphasized the importance of smoking cessation services, stating, “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.” He stressed the risk of serious complications arising from fetal growth restriction or premature birth due to smoking during pregnancy.
However, Smith cautioned against pregnant women significantly increasing their caffeine consumption in response to the study’s findings. He pointed out that very high caffeine intake, particularly from coffee, has been associated with a higher risk of miscarriage and stillbirth, factors not addressed in this research. “We only studied women who consistently had above-average levels of caffeine metabolites. We did not study women who had extremely high caffeine intake. Hence, we would not interpret our findings as indicating that current recommendations around caffeine intake should be changed.”
Fleur Parker, a senior practice coordinator at NCT, responded to the findings by highlighting the benefits of quitting smoking during pregnancy for the health of both mother and baby. However, she acknowledged that quitting can be challenging for many women, particularly those experiencing increased anxiety during pregnancy. Parker encouraged pregnant women to seek support from their midwife when trying to quit smoking.
