A pregnant mother who does not smoke and breathes in secondhand smoke has a higher chance of delivering a stillborn baby or a baby with a defect, researchers from the University of Nottingham, England, revealed in the journal Pediatrics. There is a 23% higher risk of delivering a stillborn baby and 13% higher chance of giving birth to a child with congenital birth defects.
It is important that expectant fathers who smoke either give up or smoke away from their pregnant partners, the researchers wrote. Researcher, Dr Jo Leonardi-Bee, said:
"Mothers' smoking during pregnancy is well-recognized as carrying a range of serious health risks for the unborn baby including fetal mortality, low birth weight, premature birth and a range of serious birth defects such as cleft palate, club foot and heart problems.
Since passive smoking involves exposure to the same range of tobacco toxins experienced by active smokers, albeit at lower levels, it is likely that coming into contact with second-hand smoke also increases the risk of some of all of these complications."
The authors explained that theirs is the first study to gather global research data results regarding the effects of passive smoking on pregnancy, and to estimate possible and potential risks.
The researchers looked at 19 studies which had been performed in Europe, Asia, North America and South America which focused on non-smoking pregnant women who were exposed to the environmental smoke of their partners at home or of colleagues at work.
Their aim was to determine what the effects of passive smoking might be on newborn death, congenital birth defects and miscarriage.
A single study was not found to reveal a link between passive smoking and a higher risk of miscarriage or newborn death - the increase was only observed after pooling all the results.
As we still do not know when the effects of secondhand smoke may begin, it is important to protect women from environmental tobacco smoke not only during pregnancy, but also beforehand, the authors stressed.
Fathers should be made more aware of the harmful effects their smoking might have on their unborn child.
Dr Leonardi-Bee said:
"What we still don't know is whether it is the effect of sidestream smoke that the woman inhales that increases these particular risks or whether it is the direct effect of mainstream smoke that the father inhales during smoking that affects sperm development, or possibly both. More research is needed into this issue although we already know that smoking does have an impact on sperm development, so it is very important that men quit smoking before trying for a baby."Secondhand Smoke and Adverse Fetal Outcomes in Nonsmoking Pregnant Women: A Meta-analysis"
We also need to continue to find other good public health interventions that can reduce the exposure of these women to passive smoke. One possibility could be for the partner to use smoking cessation treatments such as nicotine replacement therapy (NRT) patches as temporary abstinence interventions in the home and car when they are in the company of the woman.
The risks are related to the amount of cigarettes that are smoked - the data suggests that being exposed to around 10+ cigarettes a day is enough for the risks to be increased so it is therefore very important for men to cut down. Ultimately though, in the interests of their partner and their unborn child the best option of course would be to give up completely."
Jo Leonardi-Bee, PhD, MSc, John Britton, MD, MSc, FRCP, FFPH, Andrea Venn, PhD, MSc
Written by Christian Nordqvist