Fear of childbirth has been found to add more than an hour to labour.
No matter how prepared a pregnant woman may be when it comes to childbirth, there is little she can do about the fear factor.
A Norwegian study has found that women who fear childbirth will spend more than an hour longer in labour than those who are not afraid of delivery.
The study, published in BJOG: An International Journal of Obstetrics and Gynaecology, looked at 2206 women with an average age of 30.9 years.
Using the psychometric Wijma Delivery Expectancy Questionnaire, 7.5 per cent of the women were assessed as fearing childbirth, with reasons including being a first-time mother, being a young mother, a lack of family or social support, and past abuse or medical trauma.
Average labour length for those women was eight hours compared to six hours and 28 minutes for women who were unafraid according to the Wijma scale.
The team measured labour duration from the stage at which a woman was 3-4 centimetres dilated and had three uterine contractions every ten minutes, until delivery of the child.
Researchers also found that those who were afraid of birth were more likley to have caesarean sections or instrumental deliveries - though fear had little effect on intended method of childbirth.
Given that between five and 20 per cent of women fear delivery, the results are likely to shine a light on psychological links to intervention-free deliveries.
Samantha Salvesen Adams, Health Services Research Centre, Akershus University Hospital, University of Oslo, Norway and co-author of the research said: "Fear of childbirth seems to be an increasingly important issue in obstetric care. Our finding of longer duration of labour in women who fear childbirth is a new piece in the puzzle within this intersection between psychology and obstetrics.
"We found a link between fear of childbirth and longer duration of labour. Generally, longer labour duration increases the risk of instrumental vaginal delivery and emergency caesarean section. However, it is important to note that a large proportion of women with a fear of childbirth successfully had a vaginal delivery and therefore elective caesarean delivery should not be routinely recommended."
As those who fear childbirth are more likely to need obstetric intervention, it is hoped that the results may help with providing the right support and advice in light of psychological approaches to delivery.
For more on pregnancy and birth, visit essentialbaby.com.au.