Being told your baby is “small” on a scan is worrying. Many small babies are simply constitutionally small - healthy, growing steadily, just at the lower end of the normal range. Others are small because the placenta is not supplying enough oxygen and nutrients. This second group, called fetal growth restriction (FGR) or IUGR, affects around 5–10% of pregnancies and needs close monitoring, because the baby can become unwell in the womb.
Telling the two apart is the core of fetal medicine. It depends on accurate dating from an early scan, measurements repeated over time, and Doppler studies of blood flow in the placenta and the baby. Growth restriction that is recognised before birth carries a much lower risk of stillbirth than growth restriction that is missed.
Dr. Devang Patel, FMF (UK) accredited for the NT scan and trained in maternal-fetal medicine at Fernandez Hospital, performs and reports growth and Doppler scans himself at Divine Women’s Hospital, Gota, so findings are explained and acted on in the same visit. Consultations are available in Gujarati, Hindi or English, and partners are welcome to join the discussion.
Small baby or growth restriction?
A baby’s estimated weight is calculated from the head, abdomen and thigh bone measurements and plotted on a chart. A single small measurement does not tell you whether the baby is healthy and small or small because of a problem; the pattern over time and the Doppler findings do.
- Small for gestational age (SGA): estimated weight or abdominal size below the 10th centile, with normal Doppler and steady growth
- Fetal growth restriction: estimated weight or abdominal size below the 3rd centile, or below the 10th centile with abnormal Doppler, or growth falling across centiles
- Early-onset FGR (before 32 weeks): less common, more often linked to placental disease and pre-eclampsia, and usually more severe
- Late-onset FGR (after 32 weeks): more common, often subtle on scan, and most reliably detected by the middle cerebral artery Doppler and falling growth
Indian babies are, on average, a little smaller than those on some Western charts, so the trend over serial scans matters more than any single percentile.
Common causes and risk factors
- Placental insufficiency, often with high BP or pre-eclampsia
- Tobacco in any form - smoking, gutkha, mishri or chewing tobacco - and alcohol
- Maternal anaemia, undernutrition or a very low pre-pregnancy weight
- APLA, lupus, chronic kidney disease or long-standing diabetes with vascular changes
- Infections such as cytomegalovirus (CMV), toxoplasma or malaria
- Chromosomal or genetic conditions, especially in early, severe cases with normal Doppler
- Twins, particularly where a shared placenta is divided unequally
- A previous small baby or stillbirth, and pregnancy after IVF
How a small baby is detected
Symphysis-fundal height - measuring your bump with a tape - is a simple screening tool from about 24 weeks. A bump smaller than expected, or one that stops growing, prompts a scan. Women with risk factors are offered growth scans routinely in the third trimester, because tape measurement misses many small babies.
Accurate dating is essential. If the due date is based on the last period rather than a first-trimester scan, a baby may be wrongly labelled small, or a growth problem may be missed.
The chart used matters too. Reports from different centres may use different reference charts, so the same baby can appear on a different centile from one report to the next. Wherever possible, serial scans are plotted on one consistent chart, and your own height and weight are taken into account when interpreting the result.
Doppler studies: what each one tells us
Once a small baby is found, the anatomy is reviewed and growth is repeated no sooner than two weeks later, because shorter intervals are less accurate. Doppler studies are the key to safety in between, and they guide how often you are seen.
| Doppler finding | What it suggests | Typical plan |
|---|---|---|
| All Doppler normal, EFW 3rd–10th centile | Likely healthy small baby | Growth every 2 weeks; delivery usually around 39 weeks |
| EFW below 3rd centile, Doppler normal | Smaller baby, still compensated | Closer review; delivery usually around 37 weeks |
| Low MCA or cerebroplacental ratio | Baby redirecting blood to the brain (late FGR) | Weekly Doppler and CTG; delivery from about 37 weeks |
| Raised umbilical artery resistance | Placenta under strain | Doppler once or twice weekly; delivery usually by 37 weeks |
| Absent end-diastolic flow in umbilical artery | Significant placental disease | Admission or very frequent checks; delivery around 32–34 weeks |
| Reversed flow, abnormal ductus venosus or CTG | Baby struggling to cope | Steroids and urgent delivery planning, often from 30 weeks or earlier |
What can and cannot be done in pregnancy
There is no medicine that makes a growth-restricted baby grow faster once the placenta is affected. Trials of sildenafil, extra protein drinks and routine bed rest have not shown benefit, and none is recommended for this purpose. Admission to hospital is used for closer monitoring, not because rest itself helps.
What does help: stopping all tobacco, treating anaemia, controlling BP, and a balanced diet with enough protein (dal, paneer, curd, eggs if you eat them, sprouts and nuts). Most importantly, timely surveillance and well-judged delivery prevent the serious complications.
In early, severe cases, an amniocentesis or tests for infection may be offered to look for an underlying cause, because the answer can change the plan.
Timing and mode of delivery
The central decision is when it becomes safer for the baby to be outside than inside. Delivering too early brings the problems of prematurity; waiting too long risks the baby becoming unwell. If birth is expected before 34–35 weeks, steroid injections are given to mature the lungs, and before 32 weeks magnesium sulphate is given to protect the baby’s brain.
Many growth-restricted babies can be born vaginally after induction with continuous CTG monitoring. A caesarean is advised when Doppler shows absent or reversed flow, or when the CTG suggests the baby may not tolerate contractions. Neonatal support is arranged in advance at Divine Women’s Hospital.
After birth and the next pregnancy
Small babies are checked for low blood sugar, temperature control, jaundice and feeding in the first days. Many term babies stay with their mothers; those born early or very small may need neonatal care. Most catch up well in growth during the first two years, with regular weighing and developmental checks.
Babies born growth-restricted have a somewhat higher tendency to high BP and diabetes in adult life, which is another reason for a healthy family lifestyle as they grow.
In the next pregnancy, an early dating scan, pre-eclampsia screening, aspirin 150 mg from 12–16 weeks if the cause was placental, and serial growth scans from about 26–28 weeks are planned from the outset.
At Divine Women’s Hospital, a debrief after a growth-restricted pregnancy covers what the placental findings and any test results showed, so that the plan for next time is based on the actual cause rather than guesswork. Women who had pre-eclampsia alongside FGR also have their BP followed up after delivery.
A note on the PCPNDT Act
Pre-natal sex determination is prohibited in India under the PCPNDT Act. The sex of the baby is not detected or disclosed at any scan.
Your care, step by step
- Check the datingMeasurements are compared against an accurate first-trimester due date before any label is applied.
- Detailed assessmentAnatomy, amniotic fluid and Doppler studies separate a healthy small baby from FGR, with infection or genetic tests where needed.
- Serial surveillanceGrowth every two weeks, and Doppler or CTG weekly or more often depending on severity.
- Planned birthDelivery timed to the baby’s condition, with steroids, magnesium sulphate and neonatal support when early.
- Next-pregnancy planA debrief after birth and a written plan for aspirin and early growth scanning next time.
When to book a visit
- Your scan report says the baby is small, below the 10th centile, or has IUGR/FGR
- Your bump measures smaller than expected for your dates
- A previous baby was very small or stillborn
- You have high BP, APLA, lupus or kidney disease in pregnancy
- You used tobacco in early pregnancy or have severe anaemia
- A Doppler report mentions raised resistance or brain-sparing
Warning signs - get same-day care
- Baby’s movements reduce, stop or change pattern - come in the same day
- Severe headache, blurred vision or upper abdominal pain
- Vaginal bleeding or abdominal pain
- Leaking fluid from the vagina
Labour and emergency care are available 24 × 7. Call the hospital and come in directly.
Myths and facts
Myth: Eating more ghee and dry fruits will make a small baby grow.
Good nutrition helps, but when the placenta is the cause, extra calories mostly add to the mother’s weight. Stopping tobacco and treating anaemia have a real effect.
Myth: A small baby will have an easier normal delivery.
Growth-restricted babies have less reserve and need continuous monitoring in labour. Some need a caesarean.
Myth: Bed rest will improve the baby’s growth.
Bed rest has not been shown to improve growth and raises the risk of blood clots. Monitoring and timely delivery are what protect the baby.
Myth: If the scan shows a small baby, the due date must be wrong.
Dates are fixed by the first-trimester scan and should not be changed later to fit a small measurement. Re-dating can hide genuine growth restriction.
Frequently asked questions
What is the normal weight of a baby in the womb at each month?
As a rough guide, babies weigh about 300 g at 20 weeks, 1 kg at 28 weeks, 1.8 kg at 32 weeks, 2.6 kg at 36 weeks and around 3 kg at 39–40 weeks. What matters more than a single number is the centile and whether growth continues on follow-up scans.
What is the difference between IUGR and FGR?
They mean the same thing. FGR (fetal growth restriction) is the current term; IUGR (intrauterine growth restriction) is the older one still used on many reports.
Can eating more increase my baby’s weight?
A balanced diet with enough protein and treating anaemia support healthy growth, but in placental growth restriction, extra food alone does not make the baby grow faster. Stopping tobacco in any form makes a real difference.
Is a small baby always a problem?
No. Many babies below the 10th centile are healthy and simply small. Normal Doppler studies and steady growth on repeat scans are reassuring.
What does absent or reversed flow in the umbilical artery mean?
It means the placenta is offering high resistance to blood flow, so the baby receives less oxygen and nutrition. It is a significant finding that needs very close monitoring and usually planned early delivery.
What is brain-sparing on a Doppler report?
It describes the baby redirecting blood towards the brain when supply is limited, seen as a low middle cerebral artery resistance or cerebroplacental ratio. It is an important sign in late growth restriction.
Can FGR be prevented in my next pregnancy?
If the cause was placental, low-dose aspirin started before 16 weeks reduces the risk of early placental problems in higher-risk women. Treating APLA and high BP, and stopping tobacco, also help.
How do I count my baby’s movements?
There is no fixed number to count. Get to know your baby’s usual pattern from about 24 weeks, and if movements slow down, stop or change, contact the hospital the same day rather than waiting until the next morning.
Will my baby need NICU if it is small?
Not always. Many small babies born at or near term stay with the mother and only need extra checks on sugar, temperature and feeding. Babies born early or with significant growth restriction are more likely to need neonatal care, and this is planned before delivery.
Is it safe to have so many scans and Dopplers?
Yes. Diagnostic ultrasound and Doppler, used as indicated for monitoring a pregnancy, have a long safety record. In a growth-restricted baby, the information they give far outweighs any theoretical concern, and examinations are kept as brief as practical.