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BJOG release: Pregnancy complications in older women are mostly due to multiple pregnancy or assisted conception

News 1 September 2016

Women who give birth at a very advanced maternal age (48 years+) are at higher risk of pregnancy complications, however most can be explained by multiple pregnancy or the use of assisted conception, suggests a new study published today (1 September) in BJOG: An International Journal of Obstetrics and Gynaecology (BJOG).

The age at which women are becoming first-time mothers has steadily increased over the past 40 years. In England and Wales, the average age at childbearing has increased from 26.4 in 1975 to 30 in 2013, with a corresponding rise in the proportion of women delivering in their 30s and 40s.

This national study, using data from the UK Obstetric Surveillance System (UKOSS), examined pregnancy complications and maternal and neonatal outcomes among 233 women aged between 48 to 61 years old, compared with 454 comparison women aged 16 to 46 who gave birth in UK obstetrician-led maternity units from July 2013 to June 2014.

Of the women of advanced maternal age, 76% had conceived following in vitro fertilisation (IVF) or intra-cytoplasmic sperm injection (ICSI) compared with 4% of the younger group of women. They were also more likely to be pregnant for the first time, be overweight or obese, have pre-existing medical conditions, and be carrying a multiple pregnancy.

Results found that older women were more likely than the comparison women to have pregnancy complications and have a preterm delivery. They were also more likely to require a caesarean section and be admitted to intensive care. For example, the women of advanced maternal age had an 18% risk of developing gestational diabetes compared to 4% for younger women, they were also three times as likely to develop a gestational hypertensive disorder, their risk of experiencing heavy bleeding after birth was almost doubled and the risk of suffering placental complications was more than doubled. In addition, women of advanced maternal age had a 78% chance of having a caesarean delivery compared to a 33% risk for younger women, and were twice as likely to have a spontaneous preterm delivery.

However, the majority of these complications (except gestational diabetes, caesarean delivery and ITU admission) can be explained by the higher rate of multiple pregnancy and use of assisted conception seen in women of very advanced maternal age. The authors state that many older women depend on IVF to conceive which in turn leads to an increased chance of multiple births.

Marian Knight, Lead author and Professor of Maternal and Child Population Health at the University of Oxford, said:

“The age in which women are having their first baby has increased over the past few decades, due to a variety of social, professional and financial factors and this trend is unlikely to be reversed dramatically. Although having a baby at very advanced maternal age is still relatively uncommon in the UK, the advances in assisted reproductive technologies are contributing to increasing numbers of women giving birth outside of the ‘normal’ reproductive age.

“There are also increasing numbers of women giving birth who have health problems or complicated pregnancies. It is therefore more important than ever that woman have access to safe, high-quality maternity services regardless of their age or any other factor. The findings of this study should be considered when counselling and managing women of very advanced maternal age.”

Professor Lesley Regan, President Elect for the Royal College of Obstetricians and Gynaecologists (RCOG), said:

“While the risks should never be overplayed, women and men should be aware that all reproductive outcomes are poorer in older women. As well as potentially taking longer to get pregnant, later maternity can involve a greater risk of miscarriage, a more complicated labour, and medical intervention at the birth.

“As healthcare professionals, our role is to advise both men and women about the implications that maternal age can have for fertility, pregnancy and birth, and enable couples to make informed decisions about when to plan a family.”

Professor John Thorp, Deputy Editor-in-Chief of BJOG added:

“Previous studies have examined the impact of maternal age on the health of the mother and baby using a sample of women over 35 or 40, but this is the first study to look at women aged 48 -61 where adverse events could be more common and other risks have been accounted for.

“Much research has indicated that older women have a higher risk of pregnancy complications. This study, however, revealed that the odds were reduced when mode of conception and multiple pregnancy were taken into account. These factors should be considered by healthcare professionals when advising women.”


For media enquiries or copies of the paper please contact the RCOG press office on 020 7772 6357 or email

Notes to editors:

KE Fitzpatrick, D Tuffnell, JJ Kurinczuk and M Knight. Pregnancy at very advanced maternal age: a UK population-based cohort study. BJOG 2016: DOI: 10.1111/1471-0528.14269

The article can be found here:

This research was funded by the NIHR Programme Grants for Applied Research (PGfAR) programme (RP-PG-0608-10038).

BJOG: An International Journal of Obstetrics and Gynaecology is owned by the Royal College of Obstetricians and Gynaecologists (RCOG) but is editorially independent and published monthly by Wiley. The journal features original, peer-reviewed, high-quality medical research in all areas of obstetrics and gynaecology worldwide. Please quote ‘BJOG’ or ‘BJOG: An International Journal of Obstetrics and Gynaecology’ when referring to the journal and include the website: as a hidden link online. Sign up for new content alerts from BJOG.

The Royal College of Obstetricians and Gynaecologists is a medical charity that champions the provision of high quality women’s healthcare in the UK and beyond. It is dedicated to encouraging the study and advancing the science and practice of obstetrics and gynaecology. It does this through postgraduate medical education and training and the publication of clinical guidelines and reports on aspects of the specialty and service provision.

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