Intrauterine growth retardation
Before reading this page, it is worth reading the foetal surveillance page to get an idea of the things they do to monitor baby's well-being during pregnancy.
Definitions
There are lots of terms in what is basically the small babies page. Here are some of them:
- Intrauterine growth retardation (IUGR) - a foetus which has failed to reach its own growth potential.
- Foetal compromise - chronic situation in which conditions for normal growth and neurological development are not optimal. This has a variety of causes.
- Small-for-dates (SFD) - this simply means a foetus below the 10th centile for its gestational age. This is NOT the same as IUGR because a SFD foetus, if it follows the same centile throughout pregnancy, is likely to just be a small baby, rather than one whose growth has been restricted.
Epidemiology
Pathophysiology
Determinants of a foetus's size vary. Constitutional determinants are the most important. Essentially, they're all the genetic stuff that determine what a baby's full potential is.
Pathological determinants are the disease processes which can cause IUGR. They are listed below in the "risk factors" section.
Risk Factors
- Pre-existing maternal disease
- Complications e.g. pre-eclampsia
- Multiple pregnancy
- Smoking
- Alcohol
- Drugs
- Infection e.g. CMV
- Malnutrition
- Congenital abnormalities
Clinical Features
Not a great deal in the history. The SFD foetus may move less but since normal babies do that a lot anyway, it's a pretty non-specific sign.
Examination can be more useful. A reduction in the symphisis-fundal height may be reduced or have slowed. As pre-eclampsia is a common cause of IUGR, it's worth doing BP and urine (see pre-eclampsia to find out why).
Investigations
USS is used for diagnosis of a small-for-dates foetus. If the cause is congential abnormality, this will come up on ultrasound as well. However, one ultrasound isn't enough - serial USS is used to diagnose IUGR and often they'll do umbilical artery Doppler to see if the foetus is getting enough blood from the placenta.
Often the amniotic fluid level is reduced (known as oligohydramnios) and the foetus reduces blood flow to its brain sometimes (called "head sparing"). It's worth testing for infection with foetal blood sampling or amniocentesis. Sometimes CTG is used if the foetus is severely compromised or foetal distress present.
Management
This basically depends on what the problem is. If the foetus is growing normally, then growth should be checked 2 weekly but so long as it keeps going, no extra management is needed. Foetal compromise >36 weeks needs to be delivered, either by induction or Caesarean section.
The management of preterm foetal compromise is a little bit more complicated. The aim is to prevent serious neurological damage to the foetus but trying to leave it in there for as long as possible to avoid prematurity.
Before 34 weeks, the foetus should be reviewed 2x week and have Doppler values done. If the end-diastolic flow is absent, the mother is given steroids and daily CTG. Delivery is delayed until 34 weeks or the CTG becoming abnormal. After 34 weeks delivery is usually undertaken.
Usually, women are admitted because there is often other disease like pre-eclampsia to consider.
Prognosis
Half of stillbirths weight less than the tenth centile. Preterm delivery (spontaneous and iatrogenic) is more common. Pre-eclampsia is more common increasing maternal risk. C-section is more common as well.