Fetal growth abnormalities



this is a brief video on fetal growth abnormalities we're going to be talking about both big babies and small babies as well as how they lead up to that point and some of the consequences of large and small fetuses and babies let's start off with this chart here that shows gestational age and appropriate sizes by gestational age we see across that bottom x-axis here that we have the weeks of gestation as well as the weight of the fetus or baby and it's important to note that before the baby is delivered of course that weight is an estimated fetal weight based on the size usually obtained from ultrasound so that's an estimate but it's usually pretty accurate and it's usually a pretty good assessment of if the baby is too big or too small for gestational age a baby that falls under the 10th percentile would be called small for gestational age and that's what we're going to talk about first so small for gestational age SGA as we said is a baby whose weight falls below the 10th percentile for its gestational age on the bottom not exactly identical to small gestational age is intrauterine growth restriction now it's important to note that these two definitions IUGR and SGA aren't exactly the same you can be small for gestational age and still have normal growth intrauterine growth restriction specifically means failure to achieve potential size so a baby that's just going to be small perhaps because both of the parents were small and moms uterus is very small could be small for gestational age without intrauterine growth restriction intrauterine growth restriction is pathologic whereas SGA could be normal if it's just a very small person that falls under that 10th percentile intrauterine growth restriction can then be broken down into symmetric or asymmetric growth restriction and that ratio is about 20 to 80% symmetric to asymmetric when we're talking about symmetry here we're talking about symmetry between the head and the abdomen not left and right symmetry but a baby whose head is too big for the abdomen or abdomen is too small for the head and asymmetric is when the abdomen is too small for the head one of the definitions of IUGR is when the fundal height is 3 centimeters smaller than expected so if the fundal height is supposed to show a 30 week baby and it really is 3 centimeters or more say it's at 26 or 27 week fundal height then that's that's one way to diagnose IUGR there are several risk factors for intrauterine growth restriction some of these are listed here like maternal hypertension diabetes lupus cardiovascular disease placental infarction placental abruption the lament is cord which essentially means that the cord instead of inserting into the middle of the placenta inserts into the fetal membranes and then has to travel between the amnion and the chorion there are several causes of intrauterine growth restriction these include two Ratigan's smoking alcohol cocaine hypertension and the mother preeclampsia and the mother infections and you want to think of your torch infections such as tmv such as CMV and rubella anemia multiple gestations genetic and chromosomal abnormalities poor placental perfusion poor nutrition and anatomic abnormalities and you can see how these kind of match up with some of the risk factors and atomic abnormalities might be like of element discord placental perfusion issues might be related to cardiovascular disease if a mom has a problem with peripheral arteries nonetheless you want to try to identify the cause of the intrauterine growth restriction with karyotype ultrasound and screens for infection if a baby is suspected to have intrauterine growth restriction you do want to give special attention to that baby and monitor them more frequently with ultrasounds with non stress tests and perhaps even Doppler velocimetry one myth is that bed rest is recommended for moms who showing to have intrauterine growth restriction but major studies have been done that show that bed rest does not improve outcomes if the fetus is in distress or if mom's health is in danger because of the pregnancy you do want to induce delivery if baby is starting off on the growth curve and then all of a sudden drops off the growth curve and starts being at a much lower percentage for instance if they're usually at nine percent but they all of a sudden drop to two percent in the span of a week or so you might induce delivery if baby drops off the growth curve and in general a smaller infant has greater morbidity and mortality there's a correlation between smaller babies and more outcomes some other terms that you might apply to a baby once it is born are the birth weights a low birth weight is a baby that is born at less than 225 hundred grams a very low birth weight baby is one that is less than 1,500 grams and if a baby is smaller than 1,000 grams or one kilogram you call that extremely low birth weight now let's talk about some babies that are too big for gestational age and that's this entire area up here above the 90th percentile we're going to talk about large for gestational age again definition is a weight that's above the 90th percentile or gestational age this can also be diagnosed with fetal ultrasounds you'll see a baby that looks too big risk factors here include diabetes or gestational diabetes so this could be a pre-existing diabetes in the mom or a diabetes that started during the pregnancy obesity excess methanol weight gain advanced maternal age usually in moms that are greater than 40 years old if the fetus is a male you have a higher chance of having larger educational aged baby and some genetic disorders cause overgrowth such as beckwith Weidman syndrome causes big babies another term to know is macrosomia which litter means big body and the definition for this is arguable but it's usually agreed that it's a baby weighing over 4,000 to 4,500 grams complications of having a big baby usually arise during delivery and these include shoulder dystocia or other birth trauma jaundice poor Apgar scores that's a par scores that are lower than what's acceptable and hypoglycemia in the neonatal period hypoglycemia is usually associated with diabetes and gestational diabetes but it can also happen with macrosomia and it's also a macro sonic baby is at increased risk for hypoglycemia even in the absence of diabetes this has been a short video on fetal growth abnormalities I hope it was helpful and thank you for listening

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