Updated April 2014, next review April 2017

Explaining premature birth - risks and causes

Intrauterine growth restriction (IUGR)/Fetal growth restriction (FGR)

Intrauterine growth restriction (IUGR), also known as fetal growth restriction (FGR) is a condition in which a baby's growth slows or stops when they are in the womb.

It occurs in around 3 in every 100 pregnancies. Unborn babies with fetal growth restriction can grow so slowly in the womb that they are at risk of death or illness. If the growth restriction is severe, the baby may have to be delivered so it is a cause of premature birth.

Causes of intrauterine growth restriction

The majority of cases of IUGR/FGR are caused by failure of the placenta but there are also several other factors that could cause a baby's growth to slow down:

  • multiple pregnancy
  • the mother smoking or using drugs during pregnancy
  • the mother drinking alcohol during pregnancy
  • infection
  • Antiphospholid Syndrome.

Signs and symptoms of intrauterine growth restriction

IUGR/FGR is normally diagnosed during routine antenatal appointments. Your baby’s size is monitored throughout your pregnancy in your routine appointments. The midwife will palpate your stomach gently to feel the baby’s size, and they will measure the height of your baby.

Around 10 in every 100 babies are small for gestational age (SGA). These means they are under the tenth centile in size. Most of these are small for normal reasons, such as the mother’s size and ethnicity, but around a third will be due to intrauterine growth restriction.

Treatment for intrauterine growth restriction

If IUGR is suspected, you will be sent for a scan for confirmation. You will be closely monitored and the treatment will depend on the level of growth restriction and the stage of pregnancy you are at. If the growth restriction is severe, your healthcare team may recommend delivering the baby.

Read more about delivering a premature baby

Read more about alcohol in pregnancy

Read more about smoking in pregnancy


The causes and problems of premature birth

Your premature baby:

You can also read about


Sources

NICE (2008) Antenatal care: routine care for the  healthy pregnant woman. National Institute for Health and Clinical Excellence.

NICE (2011) CG129 Multiple pregnancy: The management of twin and triplet pregnancies in the antenatal periodNational Institute for Health and Clinical Excellence.

Norman J (2011) Preterm labour, managing risk in clinical practice. Cambridge: Cambridge University Press.

RCOG (2013) The Investigation and Management of the Small–for–Gestational–Age Fetus. The Royal College of Obstetricians and Gynaecologists.

James D, Steer P (2011) High risk pregnancy, management options. Fourth ed, Elsevier Saunders.

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