Week 10: Hear Your Baby's Heartbeat

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This is your Pea in the Podcast for week 10 of your pregnancy, I'm Bonnie Petrie joined by Dr. Laurie Swaim, an obstetrician with Houston Women's Care Associates in Houston, Texas.

So welcome to week ten, this is a big one, "Week ten is the first time in general that we can hear the baby with the Doppler and that used to be significant in the olden days before ultrasounds, or before ultrasounds were available in the office, because it was helpful for dating for people who weren't sure when their last period was, they didn't know how far pregnant they were. Then the first time that heart tones are audible, the earliest possible time that could be, is about ten weeks." And that miniature heart muscle is moving beating at 145 to 165 beats per minute.

You're also one quarter of the way through your pregnancy. Congratulations! And now your little embryo is officially a fetus and this week if you're having a boy he'll start producing his own testosterone and your little girl will have a clitoris and her ovaries will be descending but still you won't be able to see gender on an ultrasound. Now the webbing on your baby's fingers fades away this week and the webbing on his or her toes will disappear a few days after the webbing on the fingers. Tooth buds are appearing under their gums this week too. And the bones of your baby's skeleton are beginning to form. Your little bean now is slightly larger than a lime; they've almost doubled in size in the past three weeks and will double in size again over the next three.

So how are you doing? "She's fine because now she's heard the baby so she knows there's a reason that she's sick, if she's sick or tired, the usual." Now week ten is the first week in the small window between weeks 10 and 12 where you will be able to get the first invasive prenatal test available to you. We touched on it last week, it's the CVS, "with the CVS the obstetrician takes tissue of the placenta actually, cells of the placental tissue. It's either done transvaginally where a tube is passed through the cervix or transabdonimally much like an amnio. That just depends on a number of factors, most notably placental location. Then the cells are sent off to the lab, just like an amnio, for culture to look and see what the baby's chromosomal pattern or chareotype is, to make sure they have the appropriate number and the appropriate arrangement." Now CVS is considered by many to be a fairly safe invasive test with a less than 1% miscarriage rate but it's only done when the risk of a defect or disease outweighs the risk of the test so Dr. Swaim says you may not be offered this first invasive screening. "Well first of all the woman would have to want testing and there's a huge number of women now who don't want any testing, it's almost less than years ago. She has to want testing and then her risk based on her age would have to be greater than the risk of the CVS. Off the top of my head do I know what number of years that is? No. But it's probably 38 or 40 or something like that. Or if her first trimester screen was abnormal". Now at 35 your risk of having a child with Down syndrome is high enough that you may want to think about some kind of prenatal testing and that risk increases as you age. In mothers who are 35 about 1 baby in 350 are born with Down syndrome. By 40 about 1 baby in 100 is born with Down syndrome but age isn't the only factor that might make you a good candidate for a CVS, "Another time I might offer a CVS is, for example, for a woman who has already had a baby with a chromosomal rearrangement problem or if there is known to be a chromosomal rearrangement problem in one of the parents because not all chromosomal rearrangement problems are incompatible with normal life but sometimes they make reproduction kind of challenging." You might also want a CVS if you are a carrier of a disease that is gender linked like hemophilia or Duchenne muscular dystrophy. The CVS can tell you if you're carrying a boy or a girl. Now almost always your prenatal testing results will come back normal and if you've had testing this early you can breathe a sigh of relief for the many weeks ahead. But if your CVS comes back showing that your fetus has a disease or a birth defect you can start making some difficult, yet informed, decisions. Now you can dedicate some time during the rest of your pregnancy learning about caring for, and raising, a child who has a birth defect or a disease. You can also consider the best options regarding where to give birth. If your baby has a serious problem it's best to deliver at a hospital with a neo-natal intensive care unit that offers special care for newborns and if your baby has a severe defect you can also decide whether to continue your pregnancy.

Now if you decide to have the CVS you can minimize the risk to your baby. How do you do that? Well it's very important you choose someone to do it who has a long history of performing this particular test. "It's very operator dependent, I mean there are wonderful people who have done CVS a billion times and they're great at it and their risk is much lower." So don't be afraid to ask about your perinatologist or geneticist's safety record, okay? Okay. You're ten weeks pregnant, you have 30 weeks to go until the big week, week 40.

That's your Pea in the Podcast for week ten of your pregnancy. Dr. Swaim and I look forward to talking to you again next week. Enjoy this week and we'll talk to you then. I'm Bonnie Petrie, thanks for listening.