Smoking linked with stillbirth
Women who have smoked during their childbearing years have a significantly higher chance of miscarriage, stillbirth and ectopic pregnancy, research suggests.
The same study found that women exposed to passive smoking also have a higher chance of their pregnancy going wrong.
Researchers examined the link between smoke and pregnancy outcomes using historical data from more than 80,000 US women who had already gone through the menopause.
When compared with never-smoking women, those who were ever active smokers during their reproductive years had a 16% higher risk of miscarriage, 44% increased chance of stillbirth and 43% higher chance of ectopic pregnancy.
Meanwhile, those women who had never smoked but who had the highest exposure to secondhand smoke (such as being exposed to passive smoking for more than a decade as a child or for more than 10 years in a workplace) also had higher risks.
They were 17% more likely to miscarry, 55% more likely to give birth to a stillborn child, and 61% more likely to have an ectopic pregnancy.
The researchers found a dose-response relationship, with women who smoked the most or who were exposed to the highest levels of secondhand smoke having the highest risks.
Of the group, just over 5,000 of the women (6.3%) were current smokers, just under 35,000 (43%) were ex-smokers - who had smoked at least 100 cigarettes during their life - and just under 41,000 (50.6%) were classed as non-smokers.
These non-smokers had smoked no cigarettes or less than 100 during their life. All had been pregnant at least once.
The researchers, from organisations including the Roswell Park Cancer Institute in New York and the University of Massachusetts Medical School, said : "In this study, active smoking was associated with spontaneous abortion (miscarriage), stillbirth and tubal ectopic pregnancy with a signiﬁcant dose-response trend.
"Secondhand exposure to never-smoking women at the highest levels were also associated with all three adverse pregnancy outcomes with signiﬁcant dose-response trends."
The study was published online in the journal Tobacco Control.