Single mothers are most likely to suffer from poorer health later in life,a new American study has claimed. The 30-year study which surveyed thousands of mothers in the US found that those who had children out of the wedlock reported lower levels of health at age 40 than those who were married when they had their first child. And marriage,when it occurred after motherhood,did not appear to remedy the women's health problems,according to the study,led by Kristi Williams of sociology at Ohio State University. The findings suggested that public health campaigns to promote marriage,which were started in the US in 1996 and aimed at single and low-income mothers,may not improve these women's health as once hoped,the researchers said. Because many more women have out-of-wedlock children today than several decades ago,the researchers predicted an increasing public health problem as these women enter their midlife,LiveScience reported. For their research,Williams and colleagues analysed survey responses from close to 4,000 women who were ages 14 to 22 when the study began in 1979. The women were interviewed every year until 1994,and then every two years afterward until 2008. Women who had their first child out of wedlock reported lower levels of health at age 40 than did those who were married when they had their first child. The results held even after the researchers took into account factors that could influence the mother's health,including education level and health conditions that existed before 1979.