Baby girls whose mothers smoke during pregnancy may face fertility issues later in life, scientists say.
Researchers suggest that girls born to mothers who smoked while pregnant exhibit signs of increased testosterone exposure. They say this may affect their hormone and reproductive function.
The study, presented at the European Society for Paediatric Endocrinology meeting in Vienna, Austria, suggests cigarettes are an endocrine disruptor - meaning they interfere with hormone systems.
In this instance, the scientists say they can masculinise girls in the womb.
They add that daughters of women who smoked during pregnancy may suffer hormonal and reproductive health problems in the long term.
Dr Deniz Ozalp Kizilay and colleagues at Cigli State Training Hospital in Turkey measured anogenital distance (AGD) - the distance from the midpoint of the anus to the genitalia - which is regulated by testosterone levels during foetal development.
They looked at 56 newborn girls and 64 newborn boys from mothers who smoked during pregnancy.
AGD was significantly longer in the baby girls and correlated with the amount the mothers smoked. No effect was found on AGD in the boys.
Dr Kizilay said: "This significant increase in AGD in girls exposed to maternal smoking may be an indicator of excessive testosterone exposure that poses a risk for short and long-term health problems, including metabolism and fertility.
"Further investigation is needed to explain the relationship between maternal smoking, increased AGD and future health issues in girls."
Scientists say girls exposed to higher levels of male hormone testosterone in the womb are at greater risk of abnormal development and long-term negative effects on their fertility and metabolism.
However, Dr Kizilay warned that the mechanisms behind the potential reproductive problems caused by exposure to cigarette smoke in the womb were not fully understood.