Mandatory genetic screening?

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Parents probably already know this, but this is a surprise to me, Screening for Rare Genetic Disorders Now Routine in Newborns:

A March of Dimes report released today says all 50 states and the District of Columbia now require newborn screening for 21 or more so-called core disorders recommended for testing. These core disorders, 29 in all, include many rare but potentially disabling or fatal metabolic disorders. Although all states have rules or laws requiring the screenings, Pennsylvania and West Virginia have yet to implement their expanded programs, according to the organization.

The increase represents a big change since 2000, when most states screened for only four conditions and testing practices varied widely from state to state, according to March of Dimes officials.

The article ends on a weird note:

“She is beautiful, healthy, precocious, 99th percentile height and weight, just wonderful,” Mr. Swift said. “That test saved her life.”

Shout out to parents out there, do you really want your baby to be the 99th percentile in weight?


  1. Wisconsin’s standard screen is for 50 disorders. The rationale is that some may be ameliorated by early diet — using PKU as a model — although in reality PKU is more the exception. 
    With a mawling, mostly-sleeping grub-like being suddenly on their hands, parents are glad to hear they are exceptional in anything! Weight, height and head circumference are your only options up to age 6 mo.

  2. Hopefully, one day it will be a matter of routine for couples to voluntarily be tested before considering parenthood. That would be the truely unselfish and responsible thing to do.

  3. do you really want your baby to be the 99th percentile in weight? 
    YES, if it’s in proportion to height.  
    When my daughter was born and her height, weight and head circumference percentiles were 95%, 95%, 97.5%, I was elated!

  4. Yes, what pconroy said. As far as I know high length and weight in a newborn is all upside and no downside, except for the delivering mother of course! If any medically knowledgeable posters disagree, I would be interested to hear from them.

  5. Even if it’s not in proportion to height, there’s not much correlation between being fat as a baby and being fat as an adult, which I’m guessing would be the worry. And in general big=healthy when it comes to babies. 
    I remember that when my oldest daughter was 6 months old she weighed 26 pounds, which was far enough above the 97th percentile on the CDC charts that I ended up estimating how many SD above the mean it was. Thing is though that breastfed babies have a slightly different growth curve than those on formula (faster early weight gain, slower later on) so the distribution is actually slightly bimodal. 
    The tests for metabolic disorders were one of the few medical procedures we acceded to for all three of our kids.

  6. “do you really want your baby to be the 99th percentile in weight?” 
    No way, especially not for a girl. I wonder if the metabolic condition caused her to grow so big?  
    pconroy – did your wife have gestational diabetes?

  7. Ours was 95th percentile (and still is) and it is isn’t something I think anyone would wish for. That said I have to confess that tests for something like that only make sense if the parent would chose an abortion. And that seems about on par for a test for blue eyes and aborting babies that don’t have them.  
    I think many people, even those perhaps more open to abortion, see some of these tests as a wee bit scary.

  8. My wife mentioned to another mum at the Maternity Hospital “Mine is such a long baby; she’s 99th percentile in height”. A third mother intruded “Mine scored more than a hundred”.

  9. did your wife have gestational diabetes? 
    No, not at all. 
    Today my daughter is 5 yo, and is height, weight, 90% and 75% – so she’s the second tallest in her class – one boy is taller – and quite slim. She spoke her first word at about 5 months, walked at 9 months, could write her name at 2 yo and today is considered gifted – so I think being a big baby is generally correlated with increased fitness.

  10. I’ve seen ignorant health care providers quote “104th percentile” for a really big baby because they’re ignorant of what percentile means. So it might not be that mom’s fault. 
    And large height and weight is always good in a baby (the key here is height — fat babies aren’t universally good but big all around is fine). 
    Also, these are tests on NEWBORNS, abortion is an utter non-issue. The need for these is because several genetic disorders are crippling or fatal if not caught immediately but harmless or only mildly harmful if treated ASAP.

  11. I am suspicious of those charts. I think doctors are still using the charts they came up with in the 19th century. I’ve NEVER met a single parent whose baby was less than the 90th percentile. And I always ask. And believe me, parents always know.

  12. the key here is height — fat babies aren’t universally good but big all around is fine 
    This isn’t quite right. Height and weight are correlated of course, but we can try to tease apart which is more important by looking at some data – for example, NHANES III (find it here, you will want the youth dataset).  
    In this case, I look at the height and weight figures for babies of 2, 3, and 4 months. Separate each age cohort roughly into five groups (you can’t do this exactly into quintiles because the heights and weights are too granular) by height and weight. Average the reported estimate of overall health (1..5) for each group. 
    The pattern that emerges is as follows: 
    - for height/length alone, the healthiest group are the above average (4th quintile). Both the shortest and tallest group are less healthy than average. 
    - for weight, the lightest group is below average, the next three are fairly similar, and the healthiest by a significant margin is the heaviest group. 
    I also looked at the top and bottom twenty (of each age, 2 months through 11 months) for height, weight, and weight/height. The top twenty for height and weight/height are less healthy than average, while the top twenty in weight are more healthy. 
    In general it looks like the ideal is to be above average in height *and* above average in weight for that height – which will put you in top weight category. Most of the extremes are bad – but worst of all is to be small overall (so being either short or skinny is bad by itself, but together it’s even worse). 
    Average health (lower is better) for different subsets: 
    Whole group (1405 infants, 2-11 months): 1.57 
    10×20 tallest: 1.60 
    10×20 shortest: 1.70 
    10×20 biggest: 1.50 
    10×20 smallest: 1.75 
    10×20 fattest: 1.60 
    10×20 skinniest: 1.70 
    You can see that the only extreme which is healthier than the overall average is simple size. The health of those who are big overall must be a result of those who are merely above average in height and fatness. And indeed: 
    2nd group (positions 21-40, each age group): 
    For height: 1.50 
    For fatness (weight/height): 1.54 
    There’s also some suggestion that being fatter is better for younger infants (< 6 months) and isn’t as good once they start to get to standing and crawling around.

  13. Newborn screening is a pretty cost effective measure. If it is worth $1200 for an epidural to spare mom some hours of significant pain, then it is worth $200 to screen for serious conditions that could be treated and save a child suffering and disability for years or even a lifetime.  
    What is the point of developing technologies to improve the quality of our lives if we aren’t willing to use them? It must have cost some $ to develop these tests, if it is worth the time and effort to discover these tests, certainly it is worth the time and effort to improve the lives of real people by employing the tests.

  14. I want to be like many of the people in my family, 99%tile for health and longevity. Many men and women in my family lived into their late 90′s fully functional, active, productive and lucid without ever having serious illness or surgeries. That is the 99%tile I want for my children.

  15. The fatter the baby the better … for the baby. For the pre-delivery mom, not so much.

  16. Above about 4500g birthweight babies start to see worse overall health too. Could just be a result of delivery complications but the picture isn’t clear.

  17. I am suspicious of those charts. I think doctors are still using the charts they came up with in the 19th century. I’ve NEVER met a single parent whose baby was less than the 90th percentile. And I always ask. And believe me, parents always know. 
    I had two that were in the 25th percentile; of course, they were/are twins, so it was expected for them to be lower on the charts. They are still under the 50th percentile, according to the doctor’s charts, but healthy as can be, so we don’t worry much about them. Their 2 years-younger brother, on the other hand, is above the 97th percentile. No big deal, except that we’re getting asked all the time if they are triplets. 
    I will agree that we were quite happy that two of our kids were hefty babies- the two tiny ones were a bit worrisome at first. The heavier babies just seemed sturdier and less breakable than their tinier, preemie-sized sisters.

  18. is there a chance that they aren’t updating the charts for time? perhaps babies are bigger now? now that i think about there are a suspicious number of 90+ percentile babies i hear about.

  19. I almost hesitate to write this… but as an another anecdotal data point to throw on the pile, two of my kids tended toward the 60th to 70th percentiles for height, weight and head circumference when they were born. Both children are now smart and healthy.  
    My third child had a strange mix of percentiles though. 35th percentile for weight, but 99th for height and head circumference. He pretty much kept tracking that way as he grew. At six years old, he couldn’t put on his eight-year old brother’s football helmet because it was too tight on him. (I myself have a rather blocky head.) He’s the tallest boy in the class, (as a flip-side to a post above, one girl is taller), and I supect he’s going to be very tall as an adult. His mother descends from Africa by way of America, and he certainly has her distal limb proportions and thin build, though he also has a rather long torso like myself. 
    While his two siblings are, as I mentioned, both smart, they are not in the same category as him. He was given an IQ test (standard Stanford Binnet) at the start of second grade and I was shocked to learn his IQ is 137.  
    My second wife is currently pregnant, but I’ve made a conscious decision not to put too much stock in the percentiles when the baby is born. Still, I wouldn’t discount the possiblity that growth is a marker for overall good health.

  20. Maybe we’ve found the cause of the Flynn effect. 
    How has the distribution of baby size changed since, say the early 20th century?

  21. bbartlog, 
    Interesting stuff, my son was height, weight, head, 75%, 90%, 75% – and so far is getting chunkier by the day.

  22. i think about there are a suspicious number of 90+ percentile babies i hear about 
    I think they grade children as: 
    25, 50, 75, 90, 95, 97.5, 99 
    But to go from 50% to 75% for instance, only takes 1/2 an inch. So probably a high margin of error.

  23. is there a chance that they aren’t updating the charts for time? 
    While we don’t know which hoary old charts a particular doctor might be using, the CDC published updated charts in 2000. There were two previous sets widely used in the 20th century – the 1977 CDC growth charts and the earlier Stuart/Meredith charts used since 1945. I don’t know what doctors used before that, if anything, though statistics on birthweight at least have been collected in various places since the early 19th century. 
    You can read up on the methods used to put together the current charts

  24. Those charts don’t really mean all that much. Babies grow at their own rates and are not aware that they are supposed to adhere to a chart. My eldest (born a month premature) has always held firm at 5th percentile for height and weight. She was, and remains, a peanut. My 2nd was off the charts for height and weight as an infant; at 6 years old she is 25th for height/weight. My 3rd was off the charts for length and 90th for weight as an infant, at 4 years old she hovers around 10th for height and 5th for weight. They are all three on the shorter/skinnier side of the curve now despite their size as infants. 
    In particular, breastfed babies tend to grow very rapidly during the first six months and often are exceedingly pudgy; they slow down dramatically during the second half of the first year. IIRC the charts were based on formula-fed infants (who tend to have the opposite growth pattern than breastfed infants).

  25. Re: babies getting bigger  
    The most widely used charts, as bbartlog pointed out, dated from 1977 and 1945 and were based upon formula-fed babies. I think the 2000 updated charts included breastfed and formula fed babies… 
    Babies do have higher birth weights today than in the past. Pregnant women today routinely gain 30, 40, 50 or more lbs., and the high-sugar, high carb standard American diet today can indeed result in very large babies. I recall a midwife friend telling me that the average size of a newborn 100 years ago was around six lbs, vs. 7-1/2 lbs. now.  
    Breastfed babies usually grow very rapidly and are quite pudgy during the first 4-6 months, then they slow down substantially in the second half of the first yeare. Formula fed babies tend to have the opposite growth patterns. The older charts were based upon formula fed babies; so higher breastfeeding rates today could account for some of the increase in 90+ percentile babies today.  
    In my own anecdotal experience, my formula-fed firstborn was always around the 5th-10th percentile for height and weight, and still is at 8 years old; my breastfed 2nd and 3rd were off the charts as infants but now have settled into the 25th/25th and 10th/5th percentiles at ages 6 and 4 respectively. So all of them are smaller than average, but the breastfed ones were huge, chubby infants who then slimmed down substantially after the first year, and my formula-fed one held to a steady rate.

  26. 1. Most charts in use even today are based on Lula Lubchenko’s data from Denver in the 1970′s. Two problems with this data. A. Mile high city. High altitudes cause smaller birth weights. B. As many have already pointed out there is a trend towards increasing birth weights across the board. Not very well studied. My 2 cents: high carb caloric intakes during pregnacy. Lead to higher blood sugars in the mom, leading to higher blood sugar and thus higher insulin levels in the fetus. nsulin is the most important growth hormone in utero. ergo! Also witha greater Latino polulation in the US (and our proactice is 60-70 % latino). I think many these will have subclinical diabetes and thus high sugars in mom and baby and the concomittant incresed insulin levels in babies. 
    2. Pernatal testing: I am slowlely coming to the inescapable conclusion that a majority of testing is mainly “pork”. In our practice, we get around 8-10 false postives every week. These generate a lot of paperwork follow up letter etc (we do live in a litiginous world. In 20 years of practice, I have so far had one infant where maybe possibly the prenatal testing may have made a differnce to our management and her prognosis- and i use the word maybe exactly as it should be used, ie I am not sure. Most of the conditions on the screen are ones in which either there is no benefit to early diagnosis or there is no effective treatment. Unfortunately the conditions initially screened for Cong adrenal hyppolasia, hypothyroidism and PKU are the ones that make sense, the rest – diminishing returns and “pork”, ie public money beins spent to benefit the poitically connected. 
    a sceptical neonatologist

  27. “Babies do have higher birth weights today than in the past. Pregnant women today routinely gain 30, 40, 50 or more lbs., and the high-sugar, high carb standard American diet today can indeed result in very large babies. I recall a midwife friend telling me that the average size of a newborn 100 years ago was around six lbs, vs. 7-1/2 lbs. now.” 
    Ding, ding, ding! Yup, 25+ years ago doctors used to tell women that they shouldn’t gain but 15 – 20 lbs at most. Now, the guidance is much more relaxed. And mom’s diets have gotten worse too. Lots of high carb, high fructose corn syrup diets. Fat moms make fat babies. And the bigger the baby is most definitely not healthier.  

  28. Salamander, 
    The mother of my daughter gained 60 Lbs while pregnant, the mother of my son gained about 65 Lbs…

  29. Grandson #2 was 99th percentile all the way around. He’s now 17. 6’5″, 240 pounds, and size 18 clodhoppers.  
    All it means is that the kid is probably going to be one of the “big” kids.

  30. My daughter has just had her 3.5yo assessment, and I was interested to see them introduce BMI charts for the very first time. It was very reassuring to see my 95th percentile infant (3890g birthweight) come in exactly in the middle of the healthy range for her height. She’s another one who scores “104%” on the charts – at 18 months they had to measure her on the two year chart, and she still came into the 85th percentile for height. 
    Now, she is a 19kg, 110cm 3.5 yo – in a mixed class at Montessori school, taller than all her 5yo classmates bar one. 
    As bud says … just one of the tall ones. 
    Interesting, also, that our system here in Australia seems to be identical to yours in the States. Our percentiles, however, are measured as points on a graph, with lines for every 5th percent – ie 5%, 10% etc. 
    I’ve also heard from the Child Health Nurse who administers this system, that the charts in use here date back to the 1950s, with the data collected only from formula fed babies. The vast majority of babies I have contact with seem to fall into the 50th to 75th percentile, unless prem or with growth issues (ie IUGR or similar).

  31. bud, jaq, 
    Yeah, those are big kids! 
    When my daughter was an infant, we had a kid next door whose Dad was 6′ 5″, and his son was huge, very long and 30 Lbs at 3 months old!!! 
    Poor kid was so big that he didn’t walk till he was over 1.5 years, as his legs weren’t strong enough to hold up the weight…