Week 35: Group B Strep

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This is your Pea in the Podcast for week 35 of your pregnancy. I'm Bonnie Petrie joined by Dr. Laurie Swaim, an obstetrician with Houston Women's Care Associates in Houston, Texas.

This week you may be tested for a fairly common bacterial infection that could mean an IV full of antibiotics for you on delivery day, it's called Group B Strep. "Group B Strep is not a horrible pathogen to adults, it can cause bladder infections for example but in general it's not one of the bacteria that we are really afraid of in adults. But it can cause serious illness for a newborn. It can be transmitted from mom to the baby during delivery, especially vaginal delivery, but it can ascend the vagina, into the uterus, and that's how babies who are delivered by cesarean could also possibly be infected. There are very, very rare instances where Group B Strep can get also in the mother's blood and to the baby before delivery and I've seen it twice actually but that's how rare it is. A number of years ago there were strategies developed for women who carry this bacteria in order to give them antibiotics to decrease the risk of transmission to the baby during the labor. There are two types of neonatal Group B strep infections, there's 'early' which happens within the first 72 hours of the baby's life and there is 'late' which happens about days 7 to 10. By identifying women who carry this bacteria, or by prophylaxing based on the risk factors which I will talk about in a second, we have marketedly decreased the incidence of newborn of the early neonatal Group B Strep infection. To my knowledge we have not really decreased the late, but the late was not as big of a problem. This is a good thing because Group B Strep really causes horrible things. It causes pneumonias and meningitis and all sorts of things in newborns."

So you get tested right about now and the test is quick and simple, may be kind of unpleasant for you though, it involves a swab of both the vagina and rectum. The culture is then analyzed for the presence of Group B Strep. Test results are usually available within 24 to 48 hours so you'll know if you're GBS positive well before you go into labor but what happens if you go into labor before then, do you get antibiotics or not? Dr. Swaim says, 'yes'. "In the event that a woman delivers less than 37 weeks then we automatically prophylax her. The reason is because we might not have her culture back yet. The cultures are usually done around 34 to 36 weeks and we do them then because it turns out that women can colonize and uncolonize. What I mean by that is we might test you some time and you might be negative but you may be positive the next time. We want a representation of what the woman's flora is close to delivery yet still have time to get the results back before she's likely to go into labor, hence doing it at 34 to 36 weeks. Otherwise we could do it at her first visit when she has her gonorrhea, chlamydia cultures for example. But because that one is not representative of what she may look like 30 weeks down the road then we repeat it. Other times where we might not have the culture back let's say you come in at 38 weeks and we don't know what your Group B Strep is, you had no prenatal care, so we prophylax you based on other criteria which include a fever greater than 100.4 or ruptured membranes for greater than 18 hours. There are some people who have erroneously decided that women whose Group B Strep is unknown should receive antibiotics and it's not the current recommendation. Furthermore if you're positive or negative the first time it's still rechecked pregnancy because if you're negative the first time you still could be positive the next time. If you're positive the first time, the current recommendations are to still rescreen because of that colonization and uncoloization, those are the recommendations from the Centers for Disease Control."

So if you test GBS positive this week you may wonder why you waited till labor to treat it, why not just treat it now. "Because it will come back. If we give you antibiotics at 34 weeks, by 39 weeks when you're in labor you could be positive again." Are there any risks of having IV antibiotics during labor? "The antibiotics do cross the placenta and in this case we definitely want them to get to the baby. Supposedly there's some possible risk of changing the baby's intestinal flora after they're colonized after they're born. Everyone has bacteria in their intestines but I'm not so sure that that's a big risk from this antibiotic and there's also the risk that we can be selecting out bacteria that are resistant to the antibiotics that we're using which probably will happen with many, many doses of use but right now I think things are holding steady. So according to the CDC if you have tested positive for GBS but are not in the high risk category, meaning that you don't have symptoms of GBS infection and haven't already had a baby with GBS disease then your chances of delivering a baby now with Group B Strep are one in 200 if antibiotics are not given, they're one in 4,000 if antibiotics are given.

As you approach your due date, your healthcare practitioner is keeping a close eye on your blood pressure. Some people are surprised when they're concerned about blood pressure numbers that aren't actually normal when they're not pregnant. "We typically like it to be lower than normal, and 130 over 80 is not a normal blood pressure in a pregnant woman." Your doc is watching you for preecalmpsia and pregnancy induced hypertension. What is pregnancy induced hypertension? "Hypertension, or gestational hypertension, that only happens in pregnancy. You know that the woman didn't have it earlier because during the first trimester blood pressures were all normal, that it is not preecalmpsia. They don't have the protein in the urine, etc. Unfortunately the term has become somewhat interchangeable. I've noticed a lot of my colleagues will say 'oh she's got PIH' when really they mean preecalmpsia it's just easier to say PIH" So what is the difference between the two blood pressure-related conditions? "Preecalmpsia the big difference would probably be the proteinuria, the protein in the urine. People who have pregnancy induced hypertension may develop preecalmpsia." Dr. Swaim says medical management of pregnancy induced hypertension and preecalmpsia, while they're quite similar, "if you have pregnancy induced hypertension then we watch you just as closely as if you have preecalmpsia. If you have pregnancy induced hypertension at term then we deliver the baby." Who's at risk for PIH? "The typical one is the young African American teenager; that's someone who always comes to mind. It's probably more likely in multiple gestations, more likely if you already have chronic hypertension to develop what we call superimposed preecalmpsia, it's probably more likely with certain kidney diseases." First time moms and women whose sisters or mothers had PIH may also be at greater risk but, like with any of the pregnancy induced situations we've been discussing, no one is immune.

So what are the signs of PIH? Headaches, blurred vision, bright light intolerance, fatigue, nausea and vomiting, urinating in small amounts, pain in the upper right abdomen, shortness of breath and a tendency to bruise easily. Call your doctor immediately if you're having blurred vision, severe headaches, abdominal pain or if you're not urinating very often. This is probably a good time to remind you of some signs of preecalmpsia too, if you're seeing spots or flashing lights while at rest call your doctor. And a sudden increase in swelling, especially of the face, is a troublesome sign that warrants a call. Also severe headaches warrant a call. Mild swelling though is normal and your belly continues to grow. Could it actually grow any more you may be wondering? It's now six inches above your bellybutton. Your baby right now is probably more than five and half pounds and more than 20 inches long. Their little fingernails reach the tips of their fingers and all that practice sucking their thumb is paying off. They would likely be able to nurse if born this week at 35 weeks. You have just five more weeks to go until week 40.

That's your Pea in the Podcast for week 35 of your pregnancy. Dr. Swaim and I look forward to talking to you again next week. Enjoy this week. 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.