Not content to prescribe a shopping list of buggies, cots, Moses baskets, bibs, nappies, changing mats, slings, car seats, blankets, hats, romper suits and bootees, a contender on the pregnancy to-do list is the 4D baby scan.

No, the fourth dimension is not really recordable (although my understanding of quantum physics is rather shaky) it refers instead to time, where the ultrasound scan is filmed. It costs a lot of money (and the expectant parents have a fairly long shopping list already.) But is there any advantage to these scans?

Antenatal scanning is generally done in the NHS to confirm pregnancy – NHS Guide to ultrasound scans – and it is usually offered slightly later in pregnancy too, in many areas of the UK, either if problems are suspected, or, more usually, as a screening test to detect foetal abnormalities.

This scan is a choice: it’s important to note that it may look abnormal, and this may be a true positive or a false positive result. Further tests may be required and then often difficult decisions. Unfortunately, some people believe these scans are simply to enjoy looking at pictures of their baby – and although that’s nice, it is not and should not be the purpose of the test.

The other issue is that of ultrasound use in pregnancy. Ultrasound does not consist of the ionising radiation used in X-rays and CT scans and relatively speaking gives less cause for concern, in terms of potential damage.

However “safety” is not absolute. There is conflicting evidence but: for examplea review: 
Is ultrasound unsound? A review of epidemiological studies of human exposure to ultrasound suggests low birth weight is associated with frequent ultrasound (of course this does not imply causation: some babies with low birth weight may have been scanned more frequently because they were not thriving in utero) and “non right-handedness” (which sounds a bit anti-leftist, but anyway.)

 Another review – epidemiology of diagnostic ultrasound exposure during pregnancy-European committee for medical ultrasound safety – suggests that left-handed tendencies were found in males in association with more pre-natal ultrasound. Whereas this paper – the safety of prenatal ultrasound exposure in human studies suggests reports – unconfirmed – that dyslexia and delayed speech have been found in association with ultrasound, needs to be taken seriously and investigated. In fact, the only thing all researchers seem to agree on is that research into ultrasound in pregnancy is sorely needed.

Until then it would seem sensible to use ultrasound in pregnancy only when it is clinically necessary.

I had very much hoped to be at a meeting to discuss these and related issues at the Royal Society of Medicine on Wednesday 1st July at 5.30pm – but I can’t make it. It’s free – just register for it online –  and members of the public are warmly welcome.