Week 11: Nuchal Translucency

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This is your Pea in the Podcast for week 11 of your pregnancy. I'm Bonnie Petrie joined by Dr. Laurie Swaim, an obstetrician with Houston Women's Care Associates in Houston, Texas.

During week 11 you'll be offered another prenatal test but this one doesn't carry any risk of miscarriage and with it you get an up close look at your beautiful bean. Before we talk about that though let's talk about what the little one is up to. Your baby is now the size of a plum and its organ systems are all up and running, believe it or not, which means the most critical period of your baby's development is already behind you. Now it's all about growing and perfecting from here on out. So now hair follicles will start to form and finger nails and toe nails will begin. Right now the eyelids are still fused but underneath them iris' are beginning to form. Your baby has a skeleton, nerves and blood circulation. Its skin though is still paper thin and you can see right through it. Right now your baby's external genetalia is distinctly male or female, it's still very tiny but it's not unheard of for a skilled ultrasound technician to make out your baby's gender during this next prenatal scan, the nuchal translucency. The nuchal translucency, otherwise known as the nuchal fold scan, is offered between weeks 11 and 14 of your pregnancy. It uses ultrasound to measure the clear space and the tissue at the back of your baby's neck. Dr. Swaim says they're looking for signs of Down syndrome and other chromosomal abnormalities as well as major congenital heart problems and babies with abnormalities tend to accumulate more fluid at the back of their neck during the first trimester, "At this time sometimes they'll look for a nasal bone and there are other things that are thought to be associated with the development of Down syndrome but that's right we're looking for fluid collecting in the back of the baby's neck." Now to do this ultrasound your technician needs high quality ultrasound equipment and to be certified on this particular test. Now in addition to the ultrasound some doctors will draw some blood for this screen. "So the blood tests that are done are PAP A (Pregnancy Associated Protein A), HCG, sort of combined with the blood test. Some people do the nuchal translucency without the blood test and as far as I know there are no norms yet for, there's definitely no norms for higher order multiples like triplets or greater, and for twins I don't think there are norms for the blood test either so you can do the nuchal translucencies, the measurements of the babies necks, as many babies as there are. So sometimes she'll have the ultrasound and not the blood test but the ultrasound combined with the blood test is what makes it a much more sensitive test." Dr. Swaim says with the combined tests you can find out if your baby is likely to have chromosomal abnormalities with a roughly 90% accuracy. This test is still relatively new compared to the other prenatal screens you'll be offered, first trimester combined screening isn't available everywhere. "The other thing about the nuchal translucencies is not all insurance companies are on board yet and it's relatively expensive. So for patients who want testing but their insurance company won't pay for it, either they can pay for it or they can revert back to the traditional second trimester screen." But this test is becoming more common and more insurance companies are paying for it and the nuchal translucency can give you some idea about what's going on in there without risking a miscarriage. Now if the test shows a likelihood that your baby has some chromosomal problems you may then opt for an evasive test like the CVS or an amniocentesis, they'll give you a definitive answer. The nuchal translucency just can't do that.

So what's going on with you now? Your body's doing miraculous things to support your baby, "Your blood flow increases by up to 40% during your pregnancy and it does it early. Along with the breast tenderness comes breast enlargement. Your heart is putting out much more blood per minute than it was before. Your lungs have changed the way their volumes are such that you're able to extract more oxygen but give yourself the opportunity to have more oxygen on board for you and the baby. Your kidneys are filtering much, much more blood obviously because there is more blood. Your bone marrow is working harder; it's amazing the adaptations to pregnancy that occur, even more interesting that they occur early." Now your uterus has grown to be about the size of a cantaloupe but it's still tucked away in your pelvis, "It's not really until 12 weeks where it really starts to come out of the pelvis and even then it's still so little that no one is really showing. For example even the skinniest people, you can't see, they don't look pregnant." Not yet anyway but you may just be starting to feel a little more like yourself, "Technically anyway, she's supposed to start feeling better around the end of her 12th week so she may start to feel a little better around 11th and start to wake up a little bit. Other than that she's pretty much doing nothing, pretty much the late first trimester is pretty boring which is good." The late first trimester may be boring in a good way but it's also almost over. You're 11 weeks pregnant; you have 29 weeks to go until week 40.

That's your Pea in the Podcast for week 11 of your pregnancy. Dr. Swaim and I look forward to talking to you again next week. I'm Bonnie Petrie, thanks for listening.