How Ultrasonography in Pregnancy Helps in Fetal Weight Assessment & Neonatal Prognosis | IFM Kolkata

Hi, I'm Dr. Girija R. Warrier. I'm a consultant radiologist and a fetal medicine specialist at Institute of Fetal Medicine, Kolkata. Today, I'll be speaking on how ultrasonography in pregnancy can help us to determine the fetal weight and to predict the outcome of the neonate after it is born. So we do ultrasonographies in pregnancies with various intentions, but one of them is to see the weight of the baby or the growth of the baby in the mother's womb. So when a baby is born at 37 completed weeks of gestation, the baby is called a term baby and any term baby weighing less than 2.5 kg is called a low birth weight baby by definition. But there are babies who are born before term and these babies also, we must know whether the weight is appropriate for their age. So every pregnancy is divided into weeks and for every week, we have a certain range of appropriate weight which has been provided to our software. So when we scan the baby, we measure the baby's several portions of the baby like we measure the head circumference, we measure the skull diameter, abdominal circumference, the length of the long bones, etc., which is fed into the software and the software generates for us the most approximate weight of the baby in the womb. Now this weight is put into a plot on the graph of the nomogram and we get to know whether the baby's growth is falling at a normal range or it is excess or it is below the expected range of the weight. So accordingly, when the baby's weight is less than 10th percentile for that gestational age, we call the baby small for gestational age. These babies may be symmetrically small or asymmetrically small. Those babies who are symmetrically small usually have less head circumference, less length and weight altogether and they usually have a poorer outcome. Those babies who are asymmetrically small usually have normal head circumference, their brain is spared because they develop OLS later on towards the later half of the pregnancy and such late onset SGAs who are asymmetrically small usually fare well in the long run. Also we must know the reasons for the SGA, whether it is maternal, fetal causes or whether it is a cause which is related to just the pregnancy during the pregnancy, certain factors like nutritional or metabolic factors which have developed. Now maternal factors may be uncontrolled hypertension, uncontrolled diabetes, chronic renal or liver diseases etc. in the mother. Fetal causes may be fetal infections, structural abnormalities, genetic causes etc. and above all we must also see whether this growth restriction is constitutional because there is a small percentage of cases where constitutionally everybody in the family is of a small build and that could also be the reason for the baby being small. So to understand all this we must again do serial ultrasonographies several times during the pregnancy at certain intervals and keep tracking the weight of the baby to see whether the baby's growth is catching up during the pregnancy. If not, if the baby is going towards a severe fetal growth restriction, we usually terminate the baby because these pregnancies are very high risk and such babies after they are born need intensive care in neonatal units in specialized centers. So thanking you for your patient hearing, until we meet again with more interesting and important topics on fetal medicine, see you.