The best available way to assess the growth of your baby is by performing an Ultrasound scan.According to medical evidence an Ultrasound scan to assess growth (Growth scan) is not a routine investigation for all pregnant ladies, but usually done on your doctor’s recommendation. Once again it is worth emphasizing the fact that the most important and an essential investigation during pregnancy is a ‘DATING SCAN’ done at 12 weeks to confirm that your dates are correct. This will help your doctor to find out if you are having growth restriction or if your dates are wrong. Usually, if your doctor is suspicious about the growth of the baby, you will be referred for an Ultrasound scan for assessment of growth. Firstly your doctor would check if the gestation is correct by comparing with the 12 weeks dating scan. Then the doctor would perform an Ultrasound scan and check to which category of small babies your baby would fall in to. A growth scan includes assessment of the measurements around the head (Head circumference) , abdomen (abdominal circumference) and assessment of the length of the thigh bone (femur length). The Ultrasound scan machine has inbuilt mathematical formula to get the estimated weight of the baby for a particular period of pregnancy with the use of those measurements. Hence your doctor can arrive at a proper diagnosis with the help of standard charts which shows the correct and average weight for a particular period of the pregnancy. There are 3 categories of small babies during pregnancy. These are abnormal small babies, normal small babies and starving small babies ABNORMAL SMALL BABIES Fortunately this kind of babies are rare and usually these babies are small even before 24 weeks of gestation unlike the other 2 categories of babies who become small after about 24 to 28 weeks of gestation. These abnormal small babies become small due to a genetic or a chromosomal problem in the baby. majority of these babies have some kind of abnormality in their structure (eg -short ABNORMAL SMALL BABIES limbs, major heart defects, large defects in the abdominal wall known as omphalocele etc). Threfore if your baby is abnormally small you would be referred for an anomaly scan to check for anomalies of the baby. Depending on the abnormalities you will be referred for an amniocentesis (The ‘needle test’ to obtain a little bit of water around the baby to extract babies cells) to check if baby’s chromosomes are normal. NORMAL SMALL BABIES Majority of small babies fall in to this category. These babies are also called ‘small for dates’ or constitutionally small. As you know there is huge variation in height and weight in adult population. For example the range of height in females may be from 4 feet 8 inches up to 5 feet 9 inches and a female who is 4 feet and 9 inches is not abnormal as it is her genetic growth potential. Same principle applies to the growth of the baby in the womb. There can be huge variation of growth of the baby after 24- to 28 weeks of the pregnancy. Short mothers, slender, small built parents can have small babies who are completely normal. These babies would have normal amount of water around them which is an indication of having a normal blood supply through the umbilical cord and normal placenta. These babies are healthy and normal babies who are not at risk of having problems . STARVING SMALL BABIES These babies become small as their blood supply through the placenta (‘afterbirth’) and the umbilical cord is not sufficient for them. These babies need careful surveillance during the pregnancy as they can have problems during pregnancy, labor and even after delivery. This category is also called ‘growth restricted’and often known as IUGR (Intra- Uterine growth Restriction) or FGR (Fetal Growth Restriction).