Mar 18, 2010 06:23 PM
Dear Ms. Goer,
Frank A. Manning. Antepartum fetal testing: a critical appraisal Current Opinion in Obstetrics and Gynecology 2009, 21:348–352
Ruth C. Fretts, and Ugonna A. Duru, New Indications for Antepartum Testing: Making the Case for Antepartum Surveillance or Timed Delivery for Women of Advanced Maternal Age Seminars in Perinatology Volume 32, Issue 4, August 2008, Pages 312-317.
Thanks so much for your opinion, and thanks to Lamaze International,
Mar 20, 2010 10:33 PM
Well, the good news is that the perinatologist actually gave you some papers on the issue. The bad news is that he gave you "narrative reviews," meaning the author or authors collected studies and chose data from them that supports their opinion. This is quite different than a systematic review, although even systematic reviews are subject to the biases of their authors and sometimes to the problem of "garbage in, garbage out" if their component studies are flawed. At any rate, I have the papers and will read them along with some systematic reviews that I just happen to have on me because I'm working on the chapter on induction of labor for the new Obstetric Myths Vs. Research Realities. The questions that need to be answered are:
As I wrote you when you e-mailed me, I am off to visit my daughter who just had our second grandchild a couple of days ago, a beautiful home birth. (OT, but I can't resist: My daughter says her experience was so much better than the hospital birth she had with our granddaughter. She felt so much more attended to and taken care of by the midwives and was so much more able to do and be what she needed to during the labor.) I've printed the papers out, however, and I'm taking them with me. Stay tuned.
Mar 23, 2010 12:00 PM
Thank you Henci,
I am looking forward to your analysis and review.
Just a note, I contacted our local Birth Center, the only one in the area that does home births. They have an 8 month waiting list. I wish I had explored this option much earlier. I throw this out there because as the desire for home births in this country grows, so does demand. Anyone thinking about it should explore their local options as soon as they find out they are pregnant.
Mar 26, 2010 07:35 PM
Let’s start with fetal surveillance testing. The theory behind it is that fetuses that are in trouble display symptoms of that trouble by deviating from normal physiology such as how much amniotic fluid they make or physiologic responses such as how their heart rate responds to stimuli such as Braxton-Hicks contractions. By identifying those fetuses and either inducing labor or delivering by cesarean surgery, stillbirths can be prevented. Unfortunately, like electronic fetal monitoring, the best information we have, a systematic review (see my prior post with link to definition) (Lalor 2008), tell us that it hasn’t worked out that way. Biophysical profile testing in high-risk women (hypertension, intrauterine growth restriction, pregnancy longer than 42 completed wks, uterine infection, preterm rupture of membranes, diabetes, etc.) did not reduce adverse outcomes, and the two better done studies reported an increase in cesareans. Nonstress testing likewise has not been found to decrease adverse outcomes, a fact acknowledged in Manning 2009, the narrative review (which amounts to an opinion piece) whose citation you sent me. Manning, BTW, cites Lalor 2008 and then does a tap dance around the issues that testing fails to improve outcomes and concludes that “The concept of multispectral combined fetal testing including acute biophysical variables, amniotic fluid volume and arterial and venous Doppler flow velocity waveforms is established.” Establishing the concept is not, please note, at all the same thing as establishing effectiveness of testing. Manning’s conclusion is not surprising since the Lalor systematic review names him as the originator of biophysical profiling, citing a 1980 paper of his. Thus you see demonstrated live and in color why narrative reviews do not constitute evidence in the sense of practicing evidence-based medicine.
As to why these testing schemes do not work, there are three reasons for this: first, screening tests will necessarily have high false-positive rates, that is, the test will indicate a problem, but most babies with intermediate scores are actually fine and most of those who are not fine are not so compromised that they cannot withstand the continuation of the pregnancy or tolerate normal labor. Testing schemes also do not account for such normal variation as sleeping babies not being as responsive to stimuli and amniotic fluid volume varying with maternal hydration. (Case in point: I was diagnosed with “low amniotic fluid” during my last pregnancy, and two days later, membranes ruptured spontaneously, and my husband had to get the mop for the puddle on the floor and I soaked a bath towel.) Ironically, inducing labor in these cases not only exposes mother, current baby, and future babies to the excess risks of an unnecessary cesarean, but given that inducing labor almost always involves rupturing membranes and stronger contractions often over a longer time period, it is possible that a baby who might have withstood a normal labor can’t manage these additional stressors and labor ends with an urgent cesarean. This scenario will, of course, be taken as validation that testing and induction work, as in, “Thank God we got there in time.” The second reason is false negatives, that is, the test indicates that all is well, but there is a sudden fetal demise. This can occur inexplicably, an accident with the umbilical cord, perhaps, or with explanation such as the placental abruption (the placenta detaches partially or completely before delivery). The third reason is the test result is a true positive that cannot be prevented by delivery, for example, a heart defect, or some subtle problem in which delivery only defers death, so, for example, the baby becomes a SIDS statistic.
Turning to excess risk of stillbirth associated with maternal age and pregnancy duration, Fretts 2008, the other narrative review you sent me, referred to Reddy et al. (2006), a study that analyzed this relationship in 5.5 million U.S. women. The investigators found an increased risk of stillbirth in women 40 or older with increasing gestational age at term (37 wks or more) in singleton pregnancies with no congenital anomalies compared with similar women younger than 35. Quantifying that risk using the data from that paper so that you or other healthy women aged 40 or more who might be interested can determine what your risks might be is another matter. For starters, the study reported stillbirth rates in the subset of women free of medical complications (diabetes, hypertension, kidney or heart disease), and reported rates separately in women with prior births and in women who were first-time mothers, but prior c/sec was left off the list of exclusions, and investigators did not report the two factors in combination, i.e. first-time mothers free of medical complications and women with prior births free of medical complications.
Prior c/sec increases both the risk of unexplained stillbirth and explained stillbirth (stillbirth subsequent to placental attachment problems) in subsequent pregnancies, so this will affect rates in the population of women with prior births. The investigators also note that maternal medical complications are likely to be underreported in birth certificate records, the data source for this study, so some percentage of women in the “no medical risk” subpopulation probably had medical risks. Making my own calculations from data in the analysis, here is the best I can do:
· In the whole population of women with no medical conditions, 0.6 more babies per 1000 were stillborn in women 40 or older in weeks 39-40, and 1.5 more babies per 1000 were stillborn in women 40 or older in week 41 compared with women less than 35. No data are given for week 42.
· Among women having a first baby with no medical conditions, 4.2 more babies per 1000 were stillborn in pregnancies continuing beyond 37 wks (the demarcation of full-term) in women 40 or older compared with women younger than 35.
· Among women with prior births with no medical conditions, 1.7 more babies per 1000 were stillborn in pregnancies continuing beyond 37 weeks compared with women less than 35.
In summary, the excess risk in older mothers is real, but for the reasons I listed above it is probably smaller in healthy women, and especially in healthy multiparous women with no prior cesareans than the numbers I calculated from their data. We also have no idea whether routine testing with delivery for nonreassuring results or routine induction at 40 wks. will improve outcomes or what the tradeoffs would be with excess complications as a result, but based on what we know, it isn't likely to favor either policy.
Looking at induction, you should know that elective induction before 39 completed weeks, that is, the beginning of the week that ends with your due date, is not recommended because of increased risk of serious respiratory problems in the baby. In women with prior vaginal births only, there is no increased risk of cesarean, provided the cervix is ready or almost ready for labor (Bishop score 6 or more on a scale of 10). If the Bishop score is less than 6, there is an increased risk of cesarean (roughly 5% more c/sec than spontaneous labor) that is not eliminated by cervical ripening agents or techniques. In women having a first baby, the risk of excess cesarean is doubled compared with a first-time mother starting labor spontaneously, and, again, that risk is not eliminated by cervical ripening.
May 11, 2010 02:58 PM
Thank you so much for all your work on this. In the end, I asked so many questions, and at one point got so irritated, that one of the midwives in my doctor’s office just wrote down on my chart that I said no. Strangely the response from the midwives has been positive. I made my last few appointments with the older more experienced midwives who I have a good relationship with. It seems like “saying no” has given them permission to be midwives. At my 38 week appointment one of them warned me that if I went over 40 weeks they were going to suggest inducing. I told her that I wasn’t going to consent. She said, “I didn’t think you would.” Later in the conversation she told me that there is one perinatologist at the hospital who puts “induce at 40 weeks” on everyone’s chart who is AMA. The other perinatologist there does not think this is necessary but once it gets on the chart you can’t take it off and then my OBGYN office has to push for it because it is what the perinatologist at the hospital recommends. This is the same perinatologist who did my nuchal translucency and changed my due date to “immaculate conception.” When I was getting the nuchal I was also getting a bad vibe from this particular doctor. She struck me as someone who had no faith in normal child birth. At my appointment she told me that everything looked normal, but if there was a problem with the blood work she would call. At 4pm on the Friday she called and left a message on my home phone. Of course she had left the office by the time I got the message. My entire weekend was ruined. When I reached her on Monday she said, “Great news! When you walked in here you had a risk level of a 39 year old, but it turns out your risk level is much lower!” When I told her about my weekend she was very apologetic, the office was busy on Friday, there was no one else there, she had to call me because I was over 36 etc. I find it ironic that she has been the initial source of so much friction between myself and my doctor’s office since then, and I think this illustrates how one test that seemed pretty harmless can lead to a cascade of unnecessary interventions all of which provide a great deal of revenue for the hospital. I don’t think that there is nefarious intent involved here, but it is a slide into questionable clinical practices that seems to envelop the perinatal diagnostic center, the hospital, and sadly, my doctor’s office.
My son was born two weeks ago. I went into labor on the day I thought I was due and everything was straight forward and normal/natural about the delivery. This was the first delivery of three where I didn’t have a lot of bleeding and this history is the primary reason I was reluctant to attempt a home birth. My baby weighed in at a healthy 9lbs. 13oz. I am very glad I “said no” to all the scans. The last four week of my pregnancy were much less stressful than they would have been otherwise and I didn’t have to listen to any dire predictions about his size, something other friends in the same practice had to endure. I was afraid to say no, but I am glad I did. Again, thank you for your help.
I thought you might also be interested in this particular citation. The artifical larynx is used during some non stress tests to get the baby to move. This apparently is more common is some practices than in others. I have also heard that some practices use it to try to turn a breach baby. The idea being that the baby moves around so much in response to the stimulus that they sometimes turn. Of course no one in these practices seems to correlate the movement with pain.
Am J Obstet Gynecol. 1988 Jul;159(1):228-32.
Intrauterine noise levels produced in pregnant ewes by sound applied to the abdomen.
College of Liberal Arts and Sciences, Department of Speech, University of Florida, Gainesville 32611.
Sound pressure in amniotic fluid was created by application of either an electronic artificial larynx or a standard audiometric earphone to the abdominal surface of pregnant ewes. Sound transmission was assessed with a hydrophone placed near the ear of the fetus within the intact amnion. Sound pressures produced by the electronic artificial larynx located directly over the hydrophone averaged 134.9 dB, whereas the highest sound pressure produced by a similarly placed earphone was 95.2 dB. Sound transmission decreased dramatically with increasing distance between the sound source and the hydrophone; this may account for some of the variability in fetal response when the sound test is used clinically. Caution is recommended in administering the sound test until the effects of high noise levels on the fetus are better understood.
NB Jeanne Hargett: The pregnant ewe is a good model for the human pregnant uterus and fetus, because the uterus and fetus are the same size and weight and the amount of fluid is similar. This is the standard model for a pregnant human uterus and fetus for acoustical studies. The pain threshold for humans is 110 dBA and the hearing acuity of a fetus of 30+ weeks is only 5dB lower than an adult at these frequencies. Please note that decibels are a logarithmic scale and perceived loudness doubles about every 10 dBA at these intensities. Anything above 120 dB is loud enough to damage hair cells temporarily. The louder it is, the less time it takes to cause permanent damage.
May 16, 2010 02:06 AM
Congratulations! I'm happy that everything went so smoothly, and I'm glad to have been of assistance in helping you decide what path to take. Thanks for getting back to the Forum so that I and others could know how everything went, and thanks for the citation. It is yet another example of "we don't know what we don't know."
All Times America/New_York
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