Assessing Fetal Growth

Accurate assessment of the baby's growth inside the womb is one of the key tasks of good antenatal care. Problems such as growth restriction can develop unexpectedly, and are linked with a significantly increased risk of adverse outcomes, including stillbirth, fetal distress during labour, neonatal problems, or cerebral palsy. Therefore it is essential that the baby's growth is monitored carefully.

Fundal height Fundal height measurements from 26-28 weeks onwards, taken every 2-3 weeks (preferably by the same doctor ), are best first line of assessment. The measurements are taken with a centimeter tape, from the fundus (top of the uterus ) to the top of the symphysis (pubic bone ). They are marked on the growth chart to form a curve. The slope of the measurement should be similar to the slope of the three curves printed on the chart, which predict the optimal growth of your baby.

Growth restriction Slow growth is one of the most common problems that can affect the baby in the womb. If the fundal height measurements suggest there is a problem, an ultrasound scan should be arranged and the estimated fetal weight (degree of error 10-15%) plotted on the customised chart to assess whether the baby is small for gestational age. If it does record as small, assessment of Doppler flow is recommended, which indicates how well the placenta is managing the blood supply needed for the baby. If there is a serious problem, your doctor will need to discuss with you the best time to deliver the baby.

Large baby (macrosomia) Sometimes the growth curve is steep and the growth is larger than expected. A large fundal height measurement is usually no cause for concern, but if the slope of subsequent measurements is too steep, you will need an ultrasound scan to check the baby and the amniotic fluid volume. Big babies may cause problems either before or during birth (obstructed labour, shoulder dystocia etc.). However, most often they are born normally.

Customised Growth Charts Customised growth charts which are individually adjusted for you and your baby. The information required includes:

• your name, unit number and date of birth (for identification)
• your height and weight in early pregnancy
• your ethnic origin
• number of previous babies, their name, sex, gestation at birth and birthweight
• the expected date of delivery (EDD) which is usually calculated from the 'dating ultrasound'

The chart is usually printed after your pregnancy dates have been determined by ultrasound (preferably) or by last menstrual period. If neither dates are available, regular ultrasound scans are recommended to check that the baby is growing as expected.