Maternal depression - mothers more likely to suffer depression 4 years after birth than earlier

From Science Daily on 05/21/14:

Maternal depression is more common at four years following childbirth than at any other time in the first 12 months after childbirth, and there needs to be a greater focus on maternal mental health, suggests a new study. Results show that almost one in three women reported depressive symptoms in the first four years after birth. The prevalence of depressive symptoms at four years postpartum was 14.5%, and was higher than at any time-point in the first 12 months postpartum.
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Furthermore, women with one child at four years postpartum were more than twice as likely to report depressive symptoms at this time compared to women with subsequent children (22.9% and 11.3% respectively).

The strongest predictor of depressive symptoms at four years postpartum was having previously reported depressive symptoms either in early pregnancy or in the first 12 months after childbirth. Other factors associated with depressive symptoms were; young maternal age (18-24 years), stressful life events/social adversity in the year prior to the four year follow-up, intimate partner violence and low income. Exposure to intimate partner abuse in the first 12 months postpartum or in the year prior to the four year follow-up was associated with a four-fold increase in odds of reporting depressive symptoms at four years postpartum.

Editor's note:

I think there can be plenty of factors associated with this finding such as a mini empty nest syndrome as the 4 year old child is ready to enter school and the mother must find some other focus for some of her energy and efforts. Also, I have found that women with borderline personality disorder want to fill the void, the emptiness with another child, and if they do not have another child, depression ensues. As the description of the article suggests situations where there is domestic violence or conflicted spousal relationships also have high rates of depression for women and, while not mentioned, for men too.