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Analysis

A growing problem

12 February, 2010

A growing problem

Midwife researcher and Action Medical Research training fellow Tracey Mills is looking into the causes of fetal growth restriction. Here she provides the background to her research. Midwife researcher and Action Medical Research training fellow Tracey Mills is looking into the causes of fetal growth restriction. Here she provides the background to her research.

Midwives magazine: February/March 2010

Effective monitoring of fetal growth is vital in antenatal care. Problems can develop unexpectedly and fetal growth restriction (FGR) is a significant cause of perinatal mortality and morbidity, underlying a significant percentage of unexplained stillbirths. 

FGR and stillbirth

In the UK, FGR affects between 5% and 8% of pregnancies (Neerhof, 1995) and around one in every 200 babies are stillborn (Smith, 2007).

Measurement of symphysis fundal height is recommended from 24 weeks’ gestation, but this has limited effectiveness in identifying FGR, with only around 25% of affected pregnancies detected antenatally (NHS Perinatal Institute for Maternal and Child Health, 2009; Ross et al, 2008). Even if FGR is detected, there are no effective treatments – all we can do is monitor until the benefits of continuing the pregnancy are outweighed by the risk of fetal death, at which time an early delivery may be needed. If we are to impact on the rates of stillbirth, we need to significantly improve the detection and management of FGR.

Growth restricted babies are more likely to have problems with development and may be at increased risk of developing illnesses, such as heart disease and diabetes later in life (Barker and Osmond, 1986).


Boosting research

A lack of understanding of the mechanisms underlying FGR, coupled with difficulties in developing treatments for pregnancy complications has resulted in limited research and drug development in this area. Research is crucial in midwifery, but it is important to carry out research that is clinically relevant.


Boosting understanding

I am involved in a new clinic for women at increased risk of FGR. Using Doppler ultrasound scans and laboratory studies of their placentas after birth, I am investigating why blood flow to the baby can be reduced in FGR.

In normal pregnancy, Doppler ultrasound indicates that placental blood flow steadily increases over the course of pregnancy to meet the fetus’ demands for oxygen and nutrients. In contrast, in FGR, placental blood flow is reduced.

The cause of this reduced flow is unknown, but previous studies indicate that abnormal blood vessel function is a factor (Challis et al, 2000). This is important as it may be possible to reverse abnormal function by developing drugs to improve flow and possibly increase fetal growth in utero.

In addition, potassium channels are important in controlling the diameter of blood vessels and blood flow. Preliminary studies suggest that they contribute to determining blood vessel function in the placenta in normal pregnancy (Wareing et al, 2006).  The aim now is to find out how placental blood vessel function relates to the reduced blood flow in FGR, and to examine the role of potassium channels in controlling blood vessel function in pregnancy.  


Further Information

Children’s charity Action Medical Research awards research training fellowships annually. For further information, please visit: www.action.org.uk


References

Barker DJ, Osmond C. (1986) Diet and coronary heart disease in England and Wales during and after the second world war. J Epidemiol Community Health 40: 37-44.

Challis DE, et al. (2000) Glucose metabolism is elevated and vascular resistance and maternofetal transfer is normal in perfused placental cotyledons from severely growth-restricted fetuses. Pediatr Res 47: 309-15.

Neerhof MG. (1995) Causes of intrauterine growth restriction. Clin Perinatol 22(2): 375-85.

NHS Perinatal Institute for Maternal and Child Health. (2009) Detection of fetal growth restriction. See: www.perinatal.nhs.uk/growth/Detection_of_fetal_growth_restriction.pdf (accessed 9 November 2009).

Ross MG, et al. (2008) Fetal growth restriction. eMedicine: obstetrics and gynaecology. See: http://emedicine.medscape.com/article/261226-overview (accessed 9 November 2009).

Smith GCS, Fretts RC. (2007) Stillbirth. The Lancet 370(9600): 1715-25.

Wareing M, et al. (2006) Expression and function of potassium channels in the human placental vasculature. Am J Physiol Regul Integr Comp Physiol 291: R437-46.





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