Research Training Fellowship: Dr Tracey Mills | Children's Charity

Research Training Fellowship: Dr Tracey Mills

First published on 3 June 2008

Updated on 16 July 2013

What did the project achieve?

“My work has boosted understanding of what might be going wrong when babies stop growing properly in the womb,” explains Dr Tracey Mills. “These babies are at increased risk of being stillborn.1 At the moment, all we can do to help them is monitor them more closely and deliver them, often prematurely, if they are showing signs of deteriorating health. Sadly, premature birth brings its own risks, some babies still lose their lives and others develop on-going health problems.”

“Before starting this research, we already knew that poor growth of babies in the womb is linked to poor blood flow in the placenta, but the reasons for this poor blood flow weren’t fully understood,” continues Dr Mills. “We’ve discovered that a particular type of protein, from a family of proteins called potassium channels, seems important in controlling blood flow in the placenta. We’ve also found out that blood vessels from the placentas of babies with growth restriction respond abnormally when they are stretched.”

Research into these findings continues and could help in the design of new treatments for babies who stop growing properly in the womb, with the aim of preventing ill health and saving lives.

This research was completed on 30 June 2012

Why do some babies stop growing properly in the womb?

Each year, Action Medical Research awards these prestigious grants to help the brightest and best doctors and scientists develop their career in medical research. Dr Mills’ grant of £160,244 will fund her three-year study into fetal growth restriction, a common yet serious complication of pregnancy.


Dr Tracey Mills has a rare combination of talents, being both an experienced midwife and a skilful laboratory researcher. Through her hard work, she knows only too well the heartbreak that can be associated with fetal growth restriction, a serious complication of pregnancy, for which there are no effective treatments.

The most severely affected babies have to be delivered prematurely, to stop them from dying in the womb. Sadly, some still lose their lives, and others develop ongoing health problems.

Dr Mills is investigating what causes fetal growth restriction. She hopes her work will ultimately lead to new treatments.

She said: "I am absolutely delighted to have been awareded this prestigious Fellowship from Action Medical Research. I hope to make a real contribution to developing urgently needed treatments to reduce illness, disability and death in mothers and babies."

The problem

Babies who struggle to grow in the womb

Fetal growth restriction (FGR) is a serious complication of pregnancy, which occurs when a baby’s growth becomes dangerously slow, or stops, in the womb. It affects around 5-8% of pregnancies in the UK 1

Sadly, growth restricted babies are more likely to be stillborn, to die after birth, or to develop health problems. Nothing can be done to help them while they’re still in the womb, so the most severely affected babies frequently have to be delivered prematurely, in an attempt to save their lives. But premature birth in itself brings risks.

‘Growth restricted babies often need special care after delivery, due to complications associated with prematurity, breathing difficulties, low blood sugar levels and low body temperature,’ explains Dr Mills. ‘They are also more likely to have problems with development, in areas such as walking, talking and understanding. They may even be at increased risk of developing serious illnesses, such as heart disease and diabetes, much later in life.’

With so many potential dangers, growth restriction makes pregnancy an anxious time. ‘There is an urgent need for a better understanding of what causes growth restriction and for new treatments,’ says Dr Mills.

The research

Abnormal blood flow to unborn babies

In her work as a midwife, Dr Mills has cared for many women who have lost their babies to fetal growth restriction. ‘The impact of a stillbirth, or the death of a baby, is profoundly devastating for parents, and the effects extend to the wider family and beyond,’ explains Dr Mills. ‘A particularly difficult aspect is that we are often unable to explain fully what caused the baby to die.’

In this Fellowship, Dr Mills is working towards answers. Using ultrasound scans of pregnant women, and sophisticated laboratory studies of their placentas after birth, she is investigating why blood flow through the placenta to the baby can be reduced in fetal growth restriction.

Project LeaderDr Tracey Ann Mills PhD
LocationMaternal and Fetal Health Research Group, School of Clinical and Laboratory Sciences, University of Manchester
Grant awarded3 March 2008
Start date1 September 2008
End date30 June 2012
Grant amount£160,244.00
Grant codeRTF1305, GN1721

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Who benefits

Working towards an effective treatment

‘I hope that my work will improve our understanding of the causes of fetal growth restriction,’ explains Dr Mills. ‘In the longer term, this might lead to new treatments that improve blood flow in the placenta and promote the growth of the baby in the womb. An effective treatment could decrease the number of babies who die, are delivered prematurely or are ill after birth.’

A large number of babies could ultimately benefit – estimates suggest up to 37,430 may suffer fetal growth restriction each year in the UK.1, 2 Currently, five-ten% of these growth restricted babies will be stillborn or die within just a month of birth.3, 4

Throughout this Fellowship, Dr Mills will receive high quality training in cutting-edge research techniques. ‘Action Medical Research has a great reputation for investing vital funds in training research leaders of the future,’ says Dr Mills. ‘I am dedicated to continuing my career in pregnancy research as an academic midwife and would eventually like to lead a pregnancy research group. My midwifery experience has given me an in-depth understanding of the effects of pregnancy complications on women and their families, which continue to motivate my research. I hope to make a real impact on the future.’

More details

Ultrasound scans of pregnant women whose babies aren’t growing properly in the womb, because of fetal growth restriction, show that blood flow through the placenta to the baby is often reduced, limiting the transfer of nutrients to the baby. The reasons why this occurs are not fully understood, and they are the focus of Dr Mills’ Fellowship.

‘I feel extremely privileged to have this opportunity to continue my research work in this important area, says Dr Mills. ‘Pregnancy research has traditionally received significantly less funding than other areas of medicine, so there is a great deal of work to be done.’

Dr Mills’ studies involve ultrasound scans of pregnant women and laboratory studies of blood vessels taken from their placentas after birth. Around 50 women are taking part in the study – half with normal pregnancies and half with pregnancies complicated by fetal growth restriction. Using ultrasound scans performed before delivery, Dr Mills will assess the blood flow within blood vessels of both the placenta and the unborn baby.

Dr Mills is also performing laboratory studies on samples taken from the women’s placentas after the birth of their babies. Firstly, she is investigating whether differences in blood flow detected in the ultrasound scans correlate with differences in how the blood vessels function within the laboratory. Secondly, she is investigating the hypothesis that small proteins called potassium channels, which regulate the function of blood vessels and control blood flow, don’t work properly in fetal growth restriction.


  1. Neerhof MG. Causes of intrauterine growth restriction. Clin Perinatol 1995; 22 (2): 375-85.
  2. Office for National Statistics. Health Statistics Quarterly 37 (Spring 2008), Table 2.1:
  3. McIntire DD, Bloom SL, Casey BM, Leveno KJ. Birth weight in relation to morbidity and mortality among newborn infants. N Eng J Med 1999; 340:1234-8.
  4. Thornton JG, Hornbuckle J, Vail A, Spiegelhalter DJ, Levene M. Infant wellbeing at 2 years of age in the Growth Restriction Intervention Trial (GRIT): multicentred randomised controlled trial. Lancet 2004;364:513-20.
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