Newborn screening is a wonderful example of preventive medicine. Pioneered by Dr Robert Guthrie in the early 1960s, the blood-testing of newborns for treatable disorders has become almost universal in developed countries. From the first programs for phenylketonuria testing, the scope has widened to include disorders such as hypothyroidism and cystic fibrosis.

More recently, analysis by tandem mass spectrometry, which can detect over 30 rare inborn errors of protein and fatty-acid metabolism, has been introduced.1 Soon all babies in Australia will be able to be tested by tandem mass spectrometry. A simple heelprick is all that is needed. More than one baby in every 1000 (over 250 babies a year in Australia) will have a detectable disorder needing treatment. Without early detection, some of these babies would develop intellectual disability, some would develop acute life-threatening illness, and a few avoidable deaths would result. Screening for phenylketonuria alone, with subsequent treatment, has saved over 700 Australian children from moderate to severe disability since screening began.

The consequences of not having a screening test might seem trivial to an individual family — only about one chance in 1000 that anything threatening would be missed. But, for every 1% of babies in Australia that are not tested, two or three babies per year with a treatable disorder could die or suffer permanent damage.

In this issue of the Journal, Metz and colleagues (page 412) report the results of a systematic investigation of the coverage of newborn screening in South Australia for the year 1999.2 The team not only examined coverage, but carefully analysed who it was that missed out on screening. Some of the results are not surprising, but some are. Being Aboriginal, having a home birth, being in hospital for less than three days, or suffering neonatal death were all risk factors for missed screening, as were having a gestational age of less than 32 weeks, being in intensive care, having a congenital anomaly, or having a mother who normally lived in another state. (Being a twin or triplet, however, was protective — they rarely missed being screened.) Metz and colleagues concluded that, overall, about 2% of babies did not get a screening test.

The methodology used was thorough, matching newborn screening data with the SA perinatal data collection using sophisticated software. Of course, data matching is never perfect. Baby’s-surname changes are common soon after birth (even the mother’s indicated surname can change), and babies are sometimes transferred from one hospital to another. In the end, there were 413 births to which Guthrie screening cards could not be matched, and 44 unmatched cards. Even if the unmatched cards represented babies who were born interstate then transferred to South Australia, as was suspected, this would not have materially altered the finding that about 1 in every 50 babies born was not screened in 1999. This should sound a warning note to those who oversee other screening programs, many of whom have assumed a greater than 99% coverage without adequate supporting data. There has indeed been little published on newborn screening coverage, although a recent survey from London did suggest an enviable coverage of 99.9%.3

Newborns are an ideal population to screen, being “captive” for the crucial time, but the problem of early discharge is threatening this, just as screening is poised to expand into new fields. Newborn hearing screening is becoming universal in Australia, and for this, too, it will be important to ensure a very high coverage.4 Biochemical screening by means of the routine dried blood spot is also very likely to expand as new possibilities, supported by new technology, are being explored.5

The lessons from the SA study are clear. To achieve close to 100% coverage, strategies must especially target groups at high risk of not being screened, and healthcare providers need to be reminded and re-reminded about the importance of the test. In relation to the SA study, it would have been interesting to know whether some birth units had particularly high rates of missed tests — if that were the case, such units could be targeted for kindly reminders. As the authors point out, it is also important to collect a sample from newborns who die. Now that expanded testing by tandem mass spectrometry is available, firm diagnoses can sometimes be made from dried blood samples of babies who have died. In New South Wales, over a 4-year period, we have diagnosed fatty-acid-oxidation disorders in this way in three children who died 2–3 days after birth. Achieving a diagnosis makes possible either prenatal diagnosis in a future pregnancy, if desired, or early management of a subsequent baby to avoid clinical problems.

For better coverage, perhaps screening should become mandatory in Australia, as it largely is in the United States. In Australia, we have felt that parents have a right to refuse neonatal screening on behalf of their baby. But should parents be able to refuse a procedure that carries such a tiny risk and has an obvious potential benefit, and would this not infringe on the baby’s right to have what ethicists call an “open future”?6 This is a difficult question, but one that is growing in importance as the potential for well targeted newborn screening increases. At present, in our experience, only a very small number of parents refuse newborn screening, for a variety of reasons. If we feel that newborn screening tests are valuable, then we need to ensure that every baby has a chance to benefit. Few preventive medicine programs are so effective.