Older mothers are more likely to need emergency help when delivering their babies, new research suggests.
Just 7% of mothers aged 20 to 24 need an emergency Caesarean section compared with 22% of those over 40.
And the proportion who need "operative vaginal deliveries", such as the use of forceps or a vacuum device used to assist the delivery of a baby, increases from 13% among younger mothers to 24% of those aged over 40.
The new study, published in BJOG: An International Journal of Obstetrics and Gynaecology, examined 170,000 low-risk first-time mothers in Norway.
Study co-author, Lina Herstad, from the Norwegian Resource Centre for Women's Health, said: " Previous research around advanced maternal age has mainly focused on high-risk pregnancies. However, most women of advanced maternal age are healthy, of higher socioeconomic status and are low risk.
"Our results show that the proportion of operative deliveries increased substantially with maternal age in a low-risk, first-time mother cohort.
"These findings are particularly helpful for both healthcare professionals and women of advanced maternal age in decisions regarding the optimal mode of delivery."
Commenting on the research, Cathy Warwick, chief executive of the Royal College of Midwives, said: "We know that the number of women having their baby at an older age has been increasing for some years. The number of babies born to women in England and Wales, aged 40 or over, was higher in each of the last three years than at any time since the late 1940s.
"We already know that women over 40 have an increased risk of complications during pregnancy and it is important that more research is done into the needs of this group of women. Further research will help to ensure that women over 40 are given high-quality information and that appropriate resources and staffing are committed to their care. We need more midwives to achieve this."