This study is a bit surprising:
This study examines the role of the relationship between the biological parents in determining child wellbeing using longitudinal data from the Fragile Families and Child Wellbeing Study (FFCWS). We extend prior research by considering children born to unmarried parents in an investigation of the effect of the relationship structure between the biological parents on infant health and behavior. The main findings are that children born to cohabiting biological parents (i) realize better outcomes, on average, than those born to mothers who are less involved with the child's biological father, and (ii) whose parents marry within a year after childbirth do not display significantly better outcomes than children of parents who continue to cohabit. Furthermore, children born to cohabiting or visiting biological parents who end their relationship within the first year of the child's life are up to 9 percent more likely to have asthma compared to children whose biological parents remain (romantically) involved. The results are robust to a rich set of controls for socioeconomic status, health endowments, home investments, and relationship characteristics.Apparently the stress of family breakup can contribute to higher rates of asthma.