Due dateMothers who smoke and have a pre-term birth more than triple their risk of cardiovascular disease (CVD) new research has revealed.

Researchers from the University of Sydney at Royal North Shore Hospital in New South Wales, Australia, looked at data relating to more than 900,000 mothers. They found the risk of maternal CVD increased in a dose response relationship with the number and severity of pre-term births.

The study looked at data from 1994 to 2011, considering the mother’s subsequent hospital admission for CVD or death from CVD. Analyses were conducted to compare the risk for CVD among mothers classified according to smoking and pre-term birth.

The researchers found that both smoking and pre-term birth were independently and significantly associated with the risk of CVD in affected mothers. Mothers who smoked and had a pre-term birth had a 3.35 greater risk of CVD than non-smokers with term births. This was 29% greater than adding the risks of only smoking or having a pre-term birth.

The researchers also discovered that CVD risk was even greater in smoking mothers with more severe or recurrent pre-term births. In smoking women, the risk of CVD was 3.83 times greater with an extremely pre-term birth (20-33 weeks gestation) and 3.18 times greater with a moderately pre-term birth (34-36 weeks gestation), compared to non-smoking mothers with term births. Smoking women had a 4.47 greater risk of CVD with two or more pre-term births and a 3.2 greater CVD risk with one pre-term birth, compared to non-smoking mothers with term births.

Lead author Dr Anh D. Ngo, said: “Smoking and pre-term birth are established risk factors for maternal CVD. Fertility treatment is pushing up rates of pre-term birth and smoking in pregnant women remains high, so knowledge of the impact of these conditions on CVD is important for prevention efforts. This is the first study to evaluate whether smoking and pre-term birth synergistically increase mothers’ CVD risk.”

 The report was published in the European Journal of Preventive Cardiology.