Planned Caesarean sections do not protect women from postnatal depression, according to a study.
A number of small studies had produced conflicting results, but some suggested traumatic deliveries might increase the risk of postnatal depression.
However the latest study in the British Medical Journal involving more than 14,000 women gives conclusive evidence this is not the case, UK experts said.
This is helpful to both women and their doctors, they said.
Up to 15% of women experience depression after giving birth - similar to rates of depression in the population generally.
The process of labour is recognised as big event in a woman's life, and can prove stressful.
Complications during delivery that make it necessary to do an emergency Caesarean section or use implements such as forceps could make things even more stressful, some studies say.
But Professor Deidre Murphy of Dundee University, working with colleagues from Bath University, found no evidence of an increased risk of depression and the type of delivery.
They questioned the women eight weeks after they had given birth and assessed whether any showed signs of postnatal depression.
Prof Murphy said: "What this tells us is that if a woman is perceived to be at high risk of postnatal depression, offering an elective Caesarean section is not a sensible approach purely to avoid the depression.
"Even if emergency Caesarean section or assisted vaginal delivery is required, women can be reassured that there is no reason to believe that they are more likely to experience postnatal depression."
She said what was more important was ensuring that new mothers were given the support they needed, and for healthcare professionals to be mindful of which women might be at higher risk - such as those who had experienced postnatal depression before.
Prof Murphy said a growing number of women were undergoing Caesarean sections, partly because women were getting fatter and babies bigger.
"Big babies get stuck and fat women do not labour as well," she said.
The National Institute for Clinical Excellence produced guidelines last year advising doctors to discourage pregnant women from having Caesareans if they did not need them.
Prof Shaughn O'Brien, of the Royal College of Obstetricians and Gynaecologists, said the study gave "clear and conclusive evidence" that Caesarean sections were not in any way linked to postnatal depression.
The Department of Health said it was encouraging more choice in maternity services, so that whenever possible women could choose where to give birth and the type of care they would receive.
A spokeswoman said the Caesarean rate remained at 22% in 2002-03. More than half of these were emergency operations.