Women who smoke while pregnant can triple the chances of their child succumbing to a major cause of meningitis, according to new research.
Several studies have already suggested a link between passive smoking and meningococcal disease.
To investigate the association, scientists at the UK Centre for Tobacco Studies carried out a systematic review of 18 studies and pooled their results.
Their study, published in the online journal BMC Public Health , shows that exposure to second-hand smoke both in the home and womb significantly increases the risk of meningococcal disease.
Passive smoking in the home doubled the risk in children and raised it even further in the under-fives.
For children whose mothers smoked during pregnancy, the risk was three times higher than for children born into non-smoking households.
Study leader Dr Rachael Murray, from the UK Centre for Tobacco Studies at the University of Nottingham, said: "We estimate that an extra 630 cases of childhood invasive meningococcal disease every year are directly attributable to second-hand smoke in the UK alone.
"While we cannot be sure exactly how tobacco smoke is affecting these children, the findings from this study highlight consistent evidence of the further harms of smoking around children and during pregnancy, and thus parents and family members should be encouraged to not smoke in the home or around children."
Scientists estimated that each year in the UK exposure to second-hand smoke led to several hundred extra children being affected by invasive meningococcal disease.
Meningococcal bacteria are responsible for the most dangerous form of meningitis and can also invade the blood, lungs or joints.
One in 20 of those struck by invasive meningococcal disease will die despite medical attention and one in six will be left severely disabled.