Fetal Biometry & Growth Assessment

Common measurements are biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC) and femur length (FL). Depending on the formula, several measurements contribute to estimated fetal weight (EFW). The estimate has uncertainty, often around 10–15% and sometimes larger. The chart, formula and fetal sex option, when relevant, should be recorded.

The growth chart and dating method affect the centile. Use the department-approved standard consistently and record its name. RCOG updated its guidance in July 2026 after NHS England stopped using INTERGROWTH estimated-weight charts because of concerns about their performance in the NHS population. This is not a worldwide prohibition: chart choice in the UAE needs local governance and assessment of population applicability. Do not switch charts simply to obtain a more reassuring centile.

While growth is assessed at every routine scan, formal 'Growth & Doppler' assessments are specifically required for:

• Maternal Health Issues: Like high blood pressure, pre-eclampsia, or gestational diabetes.
• Placental Concerns: If previous scans showed a small placenta or abnormal uterine artery Dopplers.
• Previous Pregnancy History: If a mother has previously delivered a very small (SGA) or very large (LGA) baby.
• Suspected Growth Deviation: If the 'fundal height' (measured by your midwife or obstetrician) does not match the weeks of pregnancy.

Monitoring growth is the most effective way to ensure the timing of delivery is optimized for the baby's safety.

An EFW or AC below the 10th centile prompts assessment for a small-for-gestational-age fetus and possible growth restriction. Small size alone does not establish the cause or prove that a fetus is healthy. A falling trajectory may matter even above the 10th centile, but measurement variation must be considered. Accurate dating, anatomy, Doppler and fluid help interpret the result. Serial size measurements usually need an interval of at least two weeks to avoid overinterpreting measurement noise; wellbeing checks may be much more frequent.

Surveillance frequency depends on the size, trend, Doppler, gestation and maternal health. A repeat growth measurement is different from a Doppler or heart-rate check. Discuss which follow-up is planned and why. Large size may prompt a diabetes review and individual birth planning; EFW alone does not predict every birth complication. Routine bed rest or simply eating more is not a treatment for placental growth restriction.

Growth assessment can identify pregnancies that need closer surveillance and help balance the risks of prematurity against continuing pregnancy. It cannot guarantee prevention of stillbirth or every complication. Some small babies are healthy, while others need additional investigation and neonatal follow-up. The result should lead to a clear plan, not reassurance based only on one number.

Ask for specialist review when there is a very small measurement, a falling growth trajectory, abnormal Doppler or a maternal condition affecting placental health. Bring previous reports with dates, measurements and chart names. Contact maternity triage promptly for reduced movements rather than waiting for the next growth scan.