Why does female fertility decline with age?

In the UK almost one in five of all fertility treatments now performed in registered clinics is in women over 40.

Decline in ovarian reserve

Women are born with a fixed store of eggs in the ovaries which begins to deplete in number right from early life. Eventually, the store of eggs (the ‘ovarian reserve’) runs down leading to the menopause, which signals the end of a woman's fertile life. However, even in the years preceding the menopause her ovarian reserve is declining so markedly that cycles become irregular and fertility much less predictable.

Quality of eggs

Even those eggs which are released from the ovaries might not be as good as they once were. Studies in recent years have shown beyond doubt that the chromosome arrangements of many eggs (and the embryos which they form) are not perfectly correct, and that this problem increases as we get older.

This is why older women are at greater risk of miscarriage and of giving birth to babies with chromosomal abnormalities (such as Down syndrome). Normal embryos should contain 23 pairs of chromosomes, one from each parent, but some studies have shown that as many as 50% of all embryos derived from women of an advanced maternal age are chromosomally abnormal.

Meet the Fertility for the Over-40s team

Our dedicated Fertility for the Over-40s team includes specialists in fertility, gynaecology, obstetrics and genetics.

Professor Nick Macklon, Medical Director

Professor Macklon is a world-renowned expert in reproductive medicine. He has held professorships at the University of Utrecht in the Netherlands, the University of Southampton and the University of Copenhagen - where he is currently based. He is co-founder of the Complete Fertility Centre clinic in Southampton, and a member of the Executive Committee of the European Society of Human Reproduction.

Dr Shailaja Nair, Deputy Clinical Director

Dr Nair has more than 20 years experience in fertility and assisted reproduction. She worked as Associate Professor in a large teaching hospital and at the Cromwell IVF programme before joining the LWC in 1993. Dr Nair has extensive experience in all aspects of assisted conception, with a special interest in the egg-sharing and gamete donation programmes.

Mr Michael Summers, Consultant in Reproductive Medicine

A graduate of King’s College, Cambridge Mr Summers completed his medical training at the University of Pennsylvania School of Medicine followed by a Clinical Fellowship in Reproductive Endocrinology and Infertility at the Brigham and Women’s Hospital, Harvard Medical School. He is certified by both the American College of Obstetrics and Gynaecology (ACOG) as well as on the GMC Specialist Register as a Consultant in Reproductive Medicine. His special interests include IVF, embryo culture, embryo implantation and pre-implantation genetic diagnostics, areas of research in which he has published extensively.

Dr Mona Rahmati, Consultant Gynaecologist and Fertility Specialist

Dr Rahmati graduated and completed her training in Gynaecology, Obstetrics and Reproductive Medicine in Rene Descartes - Paris V University. Before joining the team in 2015, she was a consultant in Pitie-Salpetriere Hospital and Bluets Hospital in Paris. Her special areas of interest are recurrent implantation failure and recurrent miscarriage.

Mr Ruwan Wimalasundera, Medical Director

Mr Ruwan Wimalasundera is Medical Director of the London Ultrasound Centre and Head of Obstetrics at the world renowned University College London Hospital (UCLH). He manages all aspects of pregnancy and delivers at UCLH and the Portland Hospital.

Why does female fertility decline with age?