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IUGR

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Intrauterine Growth Restriction

A condition where the foetus does not grow at the expected rate inside the womb, typically defined as estimated foetal weight below the 10th percentile for gestational age. Associated with placental insufficiency and maternal undernutrition.

Definition

Intrauterine Growth Restriction (IUGR) — also called Foetal Growth Restriction (FGR) — is a condition in which the foetus fails to achieve its genetically determined growth potential during pregnancy. It is typically defined as an estimated foetal weight (EFW) below the 10th percentile for gestational age on standardised growth charts, combined with evidence of placental dysfunction (abnormal Doppler blood flow).

IUGR is distinct from a foetus that is simply constitutionally small — a baby of small but healthy parents may be below the 10th percentile without any growth restriction. True IUGR involves a pathological failure to grow, usually driven by placental insufficiency.

Key Things to Know

  • IUGR and preterm birth often co-occur — placental insufficiency causes both.
  • Adequate nutrition and gestational weight gain within IOM guidelines is protective but not absolute prevention.
  • The Pregnancy BMI Calculator helps monitor your gain trajectory; foetal growth is assessed by your OB-GYN via ultrasound, not weight scales.
  • Low birth weight in India is partly attributable to high rates of maternal undernutrition — a public health priority addressed through programmes like PMMVY (Pradhan Mantri Matru Vandana Yojana).

Related Calculators

Pregnancy BMI Calculator →Calculate your pre-pregnancy BMI and get IOM-recommended gestational weight gain range. Track your current pregnancy weight gain and stay on target for a healthy pregnancy.
Pregnancy Due Date Calculator →Calculate your pregnancy due date from your last menstrual period (LMP). Know your gestational age, trimester, and days remaining using Naegele's rule.

Related Terms

Gestational Weight GainGestational Weight Gain (GWG)Preterm BirthPreterm Birth (Premature Birth)Pre-eclampsiaPre-eclampsiaIOM GuidelinesInstitute of Medicine Gestational Weight Gain Guidelines (2009)

Frequently Asked Questions

IUGR is diagnosed primarily through obstetric ultrasound. The sonographer measures the baby's head circumference, abdominal circumference, and femur length to estimate foetal weight. If the estimated weight falls below the 10th percentile for gestational age on a standardised growth chart, IUGR is suspected. Doppler ultrasound of the umbilical artery is used to assess placental blood flow and distinguish placental insufficiency from constitutional smallness. Serial growth scans every 2–4 weeks are used to monitor progression.
Insufficient [gestational weight gain](/glossary/gestational-weight-gain/) — particularly when maternal nutrition is inadequate — can contribute to IUGR by limiting the nutrients and energy available to the placenta and foetus. However, IUGR more commonly results from placental dysfunction (impaired blood flow), maternal conditions like hypertension, anaemia, or infections, and structural foetal problems. Staying within IOM weight gain targets supports placental function but does not guarantee normal foetal growth if placental disease is present.
Small for Gestational Age (SGA) is a measurement descriptor — a baby whose birth weight is below the 10th percentile for their gestational age. IUGR is a pathological process — a baby that has not achieved its growth potential due to an underlying cause (usually placental insufficiency). Not all SGA babies have IUGR (some are constitutionally small), and IUGR is confirmed by abnormal Doppler blood flow, not just a small size measurement.
Babies born with IUGR face higher risks of neonatal complications including hypoglycaemia, polycythaemia, and hypothermia. Long-term, they have elevated rates of neurodevelopmental delay, learning difficulties, and metabolic syndrome (hypertension, diabetes, obesity) in adult life — a concept known as the Barker hypothesis or foetal programming. Early catch-up growth in infancy is common but excessive catch-up (rapid weight gain) increases later metabolic risk.