A few weeks before I started writing this post, which means several months ago by the time I actually get round to finishing it, I saw someone collecting for a Down’s Syndrome charity. As I chucked some money into the collecting bucket, I commented that, after all, I might need their help in days to come; for all we know, Probable Katherine could turn out to have Down’s, especially what with me being an Older Mother and all.
My sister, who was there at the time, was astonished at the word ‘might’. But didn’t I know whether the baby had Down’s? she demanded. Hadn’t I had the test done? That one where they measured the thickness of the neck? Well – um – what about the blood test? Hadn’t I had any tests for Down’s at all?
Nope, nope, nope, nope, and nope. Which all provides quite a nice lead-in to the post I was already planning to make about the reasons why.
For those who don’t know much about Down’s Syndrome testing, here’s some background information to start out. (This will be a whistle-stop overview rather than a detailed description of every possible test, so, if you’re after the latter, keep Googling.)
There are two basic categories of tests for Down’s – diagnostic and screening. Diagnostic tests are the ones that tell you definitively one way or the other whether someone has Down’s. The only way that anyone can do this is by getting a look at the chromosomes in question, which involves getting some cells, which involves some type of needle being stuck in somewhere. This is relatively easy to do on someone who’s been born – all you need is a blood sample – but it’s rather more difficult on someone whose veins are not immediately accessible on account of them still being in utero. For prenatal testing, you either have to get some of the amniotic fluid at a point where there are going to be sufficient fetal skin cells floating around in it that some can be picked up for testing, which means the pregnancy has to be something like 20 weeks along (please don’t quote that as an exact figure, because it’s probably changed since I did my medical training and may well be a few weeks earlier – but, basically, we’re talking second trimester) or you have to get some of the placenta, which can be done at the end of the first trimester. The first procedure is called amniocentesis, the second is called chorionic villus sampling, or CVS. The big drawback of both is that they involve some risk of miscarriage. This is not a high risk – although I can’t be bothered to google for exact figures right now, I believe that in the hands of someone experienced in these procedures it’s less than 1%, although that does of course raise the rather awkward Catch 22 of how they become proficient in the first place without someone somewhere out there having procedures done by someone who is as yet merely on the road to proficiency without being there yet – but it does exist.
Screening tests are the ones that just give you betting odds as to whether a particular fetus has Down’s, with the general idea that you can then decide whether or not it’s worth progressing to a diagnostic test. One way of doing this is to measure the levels of various proteins in the mother’s blood which are, on average, higher or lower in women pregnant with Down’s syndrome fetuses than with non-Down’s fetuses. This includes the double, triple, and quadruple tests (according to how many proteins are being tested) all of which are done at 15 weeks, and a different test which can be done at the end of the first trimester if you want to pay privately (the NHS only seems to offer the 15-week blood tests, and there’s a lot of variation between areas in which of those are offered – a lot of areas offer the triple test, a lot only offer the double, and I don’t know whether or not any offer the quadruple). The more proteins you get tested for the more accurate the test will be, but, at the end of the day, as I said, all any of them will give you is a figure as to the chances of your baby having Down’s, rather than a ‘yes’ or ‘no’. Another test in this category is the nuchal translucency test, which is the one my sister referred to as measuring ‘the thickness of the neck’. It actually measures the amount of fluid just under the skin of the neck, and is done at the end of the first trimester. Again, I think this test is only available privately – it’s certainly not a routine one on the NHS, although I cannot swear that there are no areas that offer it. The greatest level of accuracy comes from doing both the nuchal translucency test and the first-trimester blood test and combining the two results to look at the odds, a combination known as the OSCAR, or One-Stop Assessment of Risk.
(Incidentally, the interpretation of the results of all these tests is very dependent on exactly how pregnant you are. A week one way or the other can make a difference to what you’d expect the normal results to be, so unless the lab know fairly accurately what gestation you are you could well be given the wrong estimate of risk.)
The basic idea is that you start out with a screening test in order to get an estimate of the chance that your baby has Down’s, and then, based on that, decide whether or not to proceed to a diagnostic test and take the risk associated with that. One problem with this is that, although technically the decision on what tests to get is yours, somebody else has already long since decided the levels of risk at which it’s worth moving on to further testing, and this may not exactly be presented to you in an unbiased way. For example, while I was engaged in my big clear-out of my desk before heading off on leave, I found some leaflets advertising OSCAR testing at some local private clinic. According to the leaflets, any result below a 1 in 300 chance of Down’s Syndrome was counted as low risk, and anything over that as high risk. This means that if tests done at that clinic show a 1 in 299 chance that the fetus you’re carrying has Down’s Syndrome – less than a 1% chance – then you’ll be told that you’re at high risk. Which, of course, means that any further discussion or decision-making on the subject will be carried out with that label – High Risk – throbbing in the back of your mind. But, hey, no pressure or anything.
This is very much a your-mileage-may-vary thing, but less than a 1% chance doesn’t sound like high risk to me. Then again, to someone who really feels that having a child with Down’s would be a disaster, a one in a thousand risk might sound high. Why, exactly, is something as subjective as an opinion on whether X risk is high or low being presented as though it were some sort of immovable fact?
Incidentally, my understanding is that the choice of figure for ‘high risk’ is not totally arbitrary, but is taken from the risk of miscarriage if you progress to the more invasive testing that’s needed if you want an exact diagnosis. So, if the chance that you’re carrying a Down’s Syndrome fetus is higher than the chance of you miscarrying as a result of having a further test in order to find out for certain, then you’ll be told the test result shows a high risk. The logic behind this, as far as I can figure it, is that a potentially avoidable miscarriage as a result of amniocentesis or CVS is considered to be exactly the same level of undesirability as a potentially avoidable birth of a child with Down’s Syndrome, so deciding which of the two risks you’re going to take simply boils down to weighing up the odds and going for the one that’s less likely. Again, I’d consider that assumption… questionable.
So, as you can tell, I have some general reservations about how the tests are used and how they’re presented to patients. That’s not why I personally decided against any of them, however – I mean, I’m not actually boycotting the tests as a moral principle, or anything. If I’d wanted what information they could give me, I’d have gone for them and ignored anyone else’s opinion on the risk classification of whatever figure I was given. So, background done with, this is why Barry and I didn’t bother with any tests for Down’s:
Barry and I both knew that we would not consider a diagnosis of Down’s sufficient reason to abort. Barry used to know someone with Down’s Syndrome and thought he was a pretty cool bloke with a cracking sense of humour who, by the way, happened to have Down’s. I don’t know whether he already felt that Down’s wasn’t enough of a reason to abort or whether knowing this man was what swayed his views, just that he mentioned this person to me when the subject came up in an abstract sort of way on a previous occasion as an example of why he didn’t see Down’s as being a big problem.
While I would personally prefer not to have a child with Down’s, the choice here wouldn’t be between having a child with Down’s and not having one – it would be between having a child with Down’s and having an abortion. For me, that would be a no-brainer. Not because I object to abortion, but because I would not have found it a strong enough reason for me to have one. Down’s would be a problem to deal with, but not, as far as I can see, a catastrophe. I’d sooner spend my life dealing with whatever problems come along with having a child with Down’s Syndrome than spend my life wondering whether I could have handled it if I’d tried.
Since we both felt this way, we just worked backwards from there. Given that a prenatal diagnosis of Down’s wouldn’t change anything we did, we didn’t see any point in taking any risk of miscarriage to find out whether we were going to have a Down’s child or not. So amniocentesis and CVS weren’t options for us. Given that that was the case, and given that we also weren’t planning on taking bets on whether the baby had Down’s syndrome or not, I couldn’t see any point in going for any test that would only tell me the odds rather than giving a diagnosis. Why waste the NHS’s money? Or ours?
Barry did query that last, when I was pregnant with Jamie – he suggested that there was one possible reason to have at least a screening test, and that was that if it came back showing a very low risk then that’d be one less thing for me to worry about during the pregnancy. I thought about this for about half a second and realised the flaw in the logic immediately – I wasn’t worried about having a baby with Down’s. (I was aware of the possibility and not particularly thrilled by it, but I wasn’t worried about it, if you see the difference – it was something I figured I’d deal with if and when it happened.) So, the only possible effect a test could have on my worry levels would be to increase them. So my answer was still no. Barry, who wasn’t bothered either way as long as I was happy with the decision, shrugged, and that was that.
And if you’d asked me when I was pregnant with Jamie, that would have been that. I didn’t see sufficient reason to take the risk of the diagnostic tests and didn’t see any particularly good reason to bother with tests that wouldn’t at the end of the day tell me one way or the other, and that ruled out the lot. At the time, those were the only reasons I had. I would have told you that if I was offered a test that combined the advantages of both – zero risk to the baby and a definite answer – then, sure, I’d go for it. Why not? This time around, I realised that I wouldn’t even do that. I realised that there was, in fact, one more good reason why I wouldn’t want any tests. I don’t want to know if I’m pregnant with a baby with Down’s.
I don’t mean that in the dreadful head-in-the-sand ignore-it-and-it’ll-go-away sense. I mean that the time at which I’d want to know that my child had Down’s would not be during the pregnancy, but after it was born. I know that some people, even if they choose not to abort, do specifically want to know during the pregnancy so that they can prepare themselves; they don’t want the joy of the baby’s birth to be marred by an out-of-the-blue Down’s diagnosis. I feel exactly the opposite way – if I have to deal with a diagnosis of Down’s, then I want to deal with it at a time when it can be mitigated by the joy of a baby’s birth. I don’t want to be dealing with Down’s in the hypothetical, with a pregnancy blighted by oh-dears and oh-how-awfuls and I-don’t-know-what-to-says. If this baby has Down’s and I wait for the diagnosis until the baby’s here, then the don’t-know-what-to-say brigade have the option of saying "Congratulations! Isn’t she beautiful?" If this baby does have Down’s, then I’d rather find that out at a time when it’s just one of the many things there to discover as part of the whole adventure of getting to know a new baby.