Week 20: The Big Ultrasound

Download The Week 20 Podcast
5.80 MB 8:13 Min


This is your Pea in the Podcast for week 20 of your pregnancy. I'm Bonnie Petrie joined by Dr. Laurie Swaim, an obstetrician with Houston Women's Care Associates in Houston, Texas.

By the end of this week you'll be halfway home and during this week a couple of big things may occur. You may get the best look yet at your little one with the big anatomy ultrasound which, if you want to know, may tell you if you're having a boy or a girl. We'll talk more about that in just a minute. But also if you had an amniocentesis a couple of weeks ago you may get the results. Dr. Swaim says you will get a lot of information from this test. We get actually a picture of the chromosomes, we get that result and we also get the result of something called the amniotic fluid alpha feta protein which will help us to determine if the baby has spina bifida. So the first thing that we tell them is that their chromosomes are normal, if they are, and then we ask them if they want to know the gender and if they do then we tell them."

Now most people will get excellent news with the results of their amnio, that everything is just fine. According to the March of Dimes however, about 1 in 150 babies will be born with a chromosomal abnormality. If the amnio shows one of these disorders your doctor will share the news with you. "So we'll see them in the office and if it is an unusual problem then we always have them go through the genetic counselors also. And then we talk to them about their options. Basically do they want to continue their pregnancy or not and we certainly don't expect an answer right away although there are legal time issues as well." Now the March of Dimes says chromosomal abnormalities usually result from an error that occurs when an egg or sperm cell is developing and nothing a parent does or doesn't do before or during the pregnancy can cause a chromosomal abnormality in your baby. Now this is what is going on: sperm and egg cells each have 23 unpaired chromosomes. When an egg and sperm cell together, they form a fertilized egg with 46 chromosomes but sometimes something goes wrong before fertilization resulting in an egg or sperm cell with too many or too few chromosomes. Very often when this occurs a woman will miscarry early in pregnancy, other times she may be able to carry the baby but the baby's abnormalities are incompatible with life. But not all chromosomal abnormalities mean the baby will die. For example, a baby with Down syndrome can survive outside the womb. If an amnio shows a baby has this chromosomal abnormality, if you wish, your doctor will help you find supportive resources. "There are developmental pediatricians with whom they can each meet beforehand, there are support groups. I have patients with babies with Down syndrome and they'll definitely talk to the parents at any time, they can talk about their fears and their hopes and their beautiful babies who have Down syndrome, they're wonderful kids. If the baby looks as though it has a structural abnormality on the ultrasound, be it cardiac or sometimes babies have something called duodenal atresia, who have Down syndrome so we send them off to the pediatric surgeons so they can have some idea of what to expect. We'll send them to a neonatologist because sometimes they're born a little early or what have you or they're born at term but they have trouble, they can't go to a low risk nursery. So there's a number of consultations that can occur prior to delivery if they opt to continue the pregnancy." But again most moms and dads are able to breathe a deep sigh of relief when they get the results of their amnio because they know chromosomally at least that everything is fine.

Okay also this week many moms go in for that big anatomy ultrasound which is exciting for many because they find out if they're carrying a boy or a girl. Although the big gender reveal is what generates all the excitement about this particular prenatal test, it's not what it's for, "the purpose of having this scan is the make sure the baby's got ten fingers, ten toes, two kidneys, a normal shaped brain, a normal shaped heart, the bladder is where it's supposed to be, etc. We're looking for placenta location, the amount of amniotic fluid, etc. You make sure the uterus is a normal structure if you can tell and then as an added bonus you get to find out what it is." It's a pretty sweet bonus though. Some people get nervous when they find out their baby's gender at this ultrasound because they're afraid they'll pick a name and paint the room and then find out on the baby's birthday the sonographer was wrong. "Okay well I've delivered babies since 1989; I've only see it happen twice. That's thousands and thousands of babies." So the odds are pretty good, your tech will be correct, they'll usually let you know if they're uncertain. Oh by the way it is possible that this ultrasound will not reveal gender at all. Sometimes your baby will not cooperate and move into a position that will allow the sonographer to get a good look at the goods. Now some people swear a little bit of a sugary drink will get your baby moving so it's easier for the sonographer to see what's going on down there but that's all anecdotal, I have no idea if it works, you can ask your healthcare practitioner about what he or she thinks about that.

So let's say you found out the gender but you want to keep it to yourself. Some people make this decision because their friends or relatives are overwhelming them with suggestions about names and many other things. This, like every other decision you and your partner make throughout your pregnancy, is completely up to you. "This is your baby, your parents had the opportunity to have their own children and make their own decisions about who they're going to tell and what they're going to name it and whether they're going to have pain medicine in labor or whether the kid is going to be circumcised and who the pediatrician is going to be and all these things are your decisions." So don't let your mother or mother-in-law pressure you, if you want to keep it to yourself, then keep it to yourself. Now some people pass on prenatal blood testing and prenatal invasive testing like amnio in favor of the anatomy ultrasound, Dr. Swaim says that's fine, it's another decision that's between you and your doctor but she wants to remind you that ultrasound is not perfect. "It will miss about 3% of all anomalies even by the best people ever doing them and that's one thing that people need to understand that just because their ultrasound is normal does not guarantee them a perfect baby." But the anatomical ultrasound can show you a lot as Dr. Swaim touched on, this prenatal test will check for things like development of the head, brain, face, spine, arms, hands, fingers, heart, lungs, bowels, kidneys, bladder, legs, and feet. Now it will also check to see if there's too much or too little fluid around the baby and will make sure that everything's fine with your uterus, umbilical cord and the position of the placenta too. But it will show you some fun stuff; mine showed us our baby already had hair. "The hair is always a big comment people make, the baby's fists, they have good tone, their hands are balled into fists when they're born. They're sticking their tongue out. We had a baby, a patient of mine, really worried about it because her tongue kept sticking out, she was completely normal she just liked to stick her tongue out." So what you'll see is a baby whose head is in better proportion with the rest of its body than it has been and its legs are nearly in proper proportion to its arms. Really what you'll see is a little version of that baby you are going to meet in about 20 weeks. Right now he or she is about six and half inches long and weighs about 10 or 11 ounces. On the ultrasound they may dance and move or suck their thumb, they may play with their umbilical cord and a little boy might, embarrassingly for some parents, funny for some others, play with their penis and your sonographer may snap a few pictures for you to bring home suitable for framing.

So how are you doing as you approach the halfway mark? "She feels good, she's happy, it's usually a quick, happy visit in the office because we do the ultrasound and usually things are normal and if there's any concerns then we talk about them but other than that I think it's still a long way to go." Yes it is a long way to go but at the end of it you'll have a beautiful baby to show for it and we'll be with you every step of the way. Right now you're 20 weeks pregnant, you have just 20 weeks to go until week 40.

That's your Pea in the Podcast for week 20 of your pregnancy. Dr. Swaim and I look forward to talking to you again next week. Enjoy this week. And for a transcript of any of our Pea in the Podcasts go to our website peainthepodcast.com. For Pea in the Podcast, I'm Bonnie Petrie, thanks for listening.