Women with an unintended pregnancy were still twice as likely to have postpartum depression at 12 months.

Women who have unintended pregnancies are four times more likely to suffer from postpartum depression, research suggests.

A year after having their babies, just three per cent of women who intended to fall pregnant suffered from the condition compared to 12 per cent of women who had “mistimed” or “unwanted” pregnancies, a new study found.

The authors suggested that healthcare workers should ask women whether or not they intended to fall pregnant to help identify those at risk.

The researchers, from the University of North Carolina, questioned women about whether or not they had planned their pregnancies when they were 15 to 19 weeks pregnant. They found that 433 women had intended pregnancies, 207 said their pregnancy was “mistimed” and 40 (six per cent) said their pregnancy was unwanted. Researchers classed both unwanted and mistimed pregnancies as "unintended" ones.

The study, published in BJOG: An International Journal of Obstetrics and Gynaecology, followed up 688 women three months after they gave birth and 550 women after 12 months.

At three months, 11 per cent of women who reported unintended pregnancies were suffering from postpartum depression compared with five per cent of women who intended to fall pregnant. The figure stood at 12 per cent for unintended pregnancies and three per cent for intended pregnancies after a year.

When the authors took into account age, education and poverty status, women with an unintended pregnancy were still twice as likely to have postpartum depression at 12 months.

“While many elements may contribute to postpartum depression, the results of this study show that unintended pregnancy resulting in live birth could also be a contributing factor,” said Rebecca Mercier, co-author of the study.

“Unintended pregnancy carried to term may have a long-term effect on women.

“Healthcare professionals should therefore consider asking about pregnancy at early antepartum visits to screen for unintended pregnancy as women who report that their pregnancy was unintended or unwanted may benefit from earlier or more targeted screening both during and following pregnancy.

“Simple, low-cost screening interventions to identify women at risk could allow targeted intervention when appropriate and could potentially prevent complications from future unintended pregnancies."

Louise Silverton, director for midwifery at the Royal College of Midwives, added: “While this research was done in a country with a very different system to the UK, it does flag-up the importance of early access to midwives and maternity services for pregnant women.

“It also demonstrates the importance of postnatal care and the continued involvement of the midwife after the birth so that any problems can be identified and treated.

“We are seriously short of midwives in England and we know that postnatal care is suffering because of this. We are hearing of midwives having to make fewer postnatal visits, if at all.

“This is a concern because the problems this research highlights may go undetected and the consequences of this can be serious, for the women, for families and for the health service.”