Small baby

My gynae told me that I am having a small baby – what does that mean?

At every stage of pregnancy, there is a weight and size estimation of the fetus from 1 to 100^th centile (1 being the smallest and 100 being the biggest). If your baby measures at or below the 10^th centile on ultrasound scan, that means that you have a small baby.

Why is my baby small?

There are 2 possibilities: baby is meant to be small (but healthy), or there is an issue causing growth restriction where baby cannot grow to his/her full potential (intrauterine growth restriction). In some cases, an exact cause cannot be found and your baby may need some investigations after birth.

Baby could be meant to be small (but healthy) because of a variety of factors including:

• You or your partner were a small baby
• You or your partner is petite 
• Your ethnicity (certain ethnicities e.g. Asian babies tend to be smaller than Caucasian babies)
• You are carrying a girl (smaller compared to boys)

Baby could be facing growth restriction because of factors including:

• Abnormal placental function e.g. in cases of pre-existing hypertension or pre-eclampsia, increased resistance in blood flow within blood vessels supplying your uterus, smoking or drug use
• Baby has a genetic or structural abnormality
• Baby has picked up an infection that has affected growth  
• You have an abnormally shaped uterus that restricts baby’s space to grow e.g. large uterine fibroids 
• You have had a growth restricted/small babies in the past 
• You are an older mother
• You are over-exercising or not putting on weight yourself 
• You have medical conditions e.g. diabetes, kidney issues 
• You are having multiple pregnancies e.g. twins 
• You had severe hyperemesis gravidarum during this pregnancy 
• You had heavy vaginal bleeding during this pregnancy 

What risks do small babies have?

If you baby is meant to be small (but healthy), there is no issues with your pregnancy.

If your baby is growth restricted, there is an increased risk of stillbirth (baby’s heartbeat stopping suddenly) or not doing well after birth. This increases your chance of needing a premature delivery. The earlier in pregnancy your baby is diagnosed to be small, and the smaller he/she is on ultrasound, the poorer the outlook is. Babies who are noted to be small earlier in pregnancy tend to have a higher chance of being affected by infection or genetic problems. 

You will require additional ultrasound scans and antenatal visits with your gynaecologist for close monitoring.

Can I carry my (small) baby to term?

If your baby is meant to small (but healthy), you will be able to carry your baby to term. 

If your baby is growth restricted, the timing and method of delivery will depend on a few factors including:

• Whether your baby is continuing to put on weight while in your uterus 
• Blood flow in the umbilical cord and in his/her brain (dopplers)
• Amniotic fluid level in your water bag 
• Your baby’s heart trace (on cardiotocography)

Every case needs to be individualised and your gynaecologist will advise you on this.

Can I have a normal vaginal birth if my baby is small?

If your pregnancy has no other issues, you may be able to have a normal vaginal birth. You will need close monitoring throughout the process, as baby (being small) has a higher chance of having an abnormal heart trace during labour requiring an emergency C-section.

If your baby’s growth is severely restricted, there is abnormal blood flow/ low amniotic fluid level on ultrasound scan, or if your baby’s heart trace is abnormal, he/she may not be able to tolerate the stress of natural labour and your gynaecologist may recommend a C-section. Your baby will need to be checked by the neonatologist on birth. 

I delivered a small baby previously. Will I have a small baby again this pregnancy?

That depends on the cause of your small baby previously. If the cause is modifiable e.g. better control of medical problems, stop smoking – these should be done immediately. For example, if you had pre-eclampsia in your previous pregnancy that resulted in a small baby, your gynaecologist will be able to start you on aspirin early in this pregnancy. 

Certain factors that are non-modifiable cannot be helped – however, your gynaecologist will be able to arrange for additional ultrasound scans to monitor the growth of your baby closely.