Intra-uterine growth restriction: when the baby is measuring smaller than expected

How it is picked up

Two things are tracked through pregnancy: the height of the top of the uterus (the fundal height), measured at routine antenatal visits, and the baby's measurements on ultrasound — head size, abdominal circumference, femur length and estimated weight, plotted against what is expected for the number of weeks. If either falls behind, or drops across two scans rather than staying on its own curve, that is when IUGR is considered. A single measurement on the smaller side is not automatically IUGR — the pattern over time matters more than any one number.

What can contribute to it

There is rarely one single cause, and in a good number of cases no clear cause is ever found. In general terms, growth restriction is more often seen where the placenta is not supplying the baby as efficiently as it should, where the mother has a condition such as high blood pressure, diabetes, anaemia or thyroid disease that affects blood flow or nutrition, in a multiple pregnancy where two or more babies are sharing the same resources, or where there is a history of smoking or a low pre-pregnancy weight. None of this is a checklist you can run against your own symptoms — a scan and an examination are what actually establish whether growth restriction is present, not a list of risk factors on a page. Some of these overlapping conditions are covered in more detail on our pages on thyroid disorders in pregnancy and high-risk pregnancy.

What closer monitoring usually involves

Once IUGR is suspected or confirmed, the pregnancy is followed more closely rather than left to the standard schedule. That typically means growth scans repeated every few weeks to see whether the baby is continuing to grow along its own curve, a Doppler scan to check blood flow through the umbilical cord and, where relevant, the baby's own blood vessels, and monitoring of the amount of amniotic fluid, which tends to fall when the placenta is under strain. In later pregnancy this can extend to more frequent visits and, in some cases, monitoring the baby's heart rate pattern directly. None of this is uncomfortable or invasive beyond a standard scan and a blood pressure check.

What it means for how the pregnancy is managed

Growth restriction changes how closely a pregnancy is watched; it does not automatically change when or how the baby is delivered. That decision — whether to continue monitoring, bring forward delivery, or manage the labour differently — is made from the actual scan findings and how the baby is tolerating the pregnancy at that point, discussed with you directly rather than decided in advance from the label alone. Many babies with IUGR are simply smaller and healthy; the point of monitoring is to identify the smaller group where the placenta genuinely cannot keep up, early enough to act.

Why closer monitoring matters

The reason IUGR is taken seriously is that a baby who is not getting enough through the placenta is more vulnerable to problems both before and around the time of birth. Regular monitoring exists precisely to catch a struggling baby well before it becomes an emergency, and the great majority of growth-restricted pregnancies that are being watched properly go on to deliver safely. If you are told your baby is measuring small, the right response is to keep every scan and monitoring appointment, not to worry between them.

Who manages this

Dr. Mayur Pai (MBBS, MS Obstetrics & Gynaecology), with 15 years in practice, manages growth-restricted pregnancies himself, from the first scan that raises the question through to delivery, at the hospital in Vaddem, Vasco-da-Gama.

This page is for general education and is not personal medical advice. Treatment depends on your own examination and reports, so please speak to a doctor about your situation. We do not carry out or offer sex determination of any kind.