Researchers found that among nearly 13 000 US mothers of pre-schoolers, those who were both depressed and tended to have violent arguments with their partner were more than twice as likely as other moms to use spanking as a form of punishment.
This, the study found, was regardless of whether their children had any chronic behavioural problems, as assessed through interviews with teachers.
It's known that depression rates are high among women in abusive relationships. These new findings, say the researchers, give more insight into how the two problems affect children.
Dr. Michael Silverstein and colleagues at Boston University School of Medicine report the findings in the Archives of Disease in Childhood.
The researchers based their results on data from 12 764 mother-child pairs taking part in an ongoing government study of child development, which included face-to-face interviews with parents and teachers.
At the outset, when the children were in kindergarten, mothers were asked whether and how often they spanked their children. Each mother also completed a standard measure of depression symptoms, and was asked whether she and her partner ever had arguments in which they would "end up hitting or throwing things at each other.
Silverstein's team found that the combination of depression and abuse was more strongly linked to spanking than was the child's actual behaviour; just as many children with good self control were spanked as those with poor self control.
The American Academy of Pediatrics discourages parents from using spanking to discipline their children, and some studies have linked spanking to a higher risk of aggressive behaviour as kids get older.
Efforts to curb physical punishment, according to Silverstein's team, should take into consideration the sometimes complex reasons that parents use such discipline.