"Babies practise frowning in the womb so they can show when they are unhappy after birth," reports the Daily Mirror.
The story comes from a small study that looked at '4-D' ultrasound scans of the facial movements of 15 unborn babies during the later stages of pregnancy. These 4-D scans combine detailed 3-D images over time. They can provide a real-time moving image of the baby while it’s still in the womb.
The researchers found that the babies, as they matured, showed more complex facial expressions including more complete signs of pain and distress. These signs included lowered brows, a wrinkled nose and parted lips. It is important to highlight that the study did not show that the babies were actually in pain.
The researchers’ theory is that the babies were just practising these expressions. As any sleep-deprived parent will tell you, crying is a newborn’s main method of communication. It may be the case that the babies were pulling faces to prepare for life after birth, which is an interesting, but still unproven, hypothesis.
The study was carried out by researchers from the University of Durham and Lancaster University. There is no information about external funding. The study was published in the peer-reviewed open-access journal PLoS One.
The study was covered fairly in the media. Most papers pointed out the researchers’ conclusions that the unborn babies were not actually in pain – just practising “the faces they’ll need out in the big bad world” as the Daily Mail put it.
This was a study of the facial movements of 15 foetuses during weeks 24 to 36 in the womb. Researchers aimed to show that foetal facial expression becomes increasingly complex from the second (around weeks 14 to 27) to third trimester (weeks 28 onwards) of pregnancy. In particular, they set out to test the theory that, as healthy foetuses mature, their facial movements can express recognisable signs of pain or distress.
They say that, with advances in treatments for babies still in the womb, the question of identifying foetal facial expressions, especially those of pain, is becoming increasingly important.
Researchers used 4-D ultrasound scans to observe the facial expressions of 15 healthy foetuses – eight girls and seven boys – during the second and third trimesters of pregnancy.
The faces and upper bodies of the unborn babies were scanned for 10 minutes at 24, 28, 32 and 36 weeks of pregnancy. The unborn babies were not stimulated during these observation periods.
Using an accepted system of coding, researchers had previously identified 19 facial movements that could be observed on foetuses and coded from the 4-D scans. In particular, they identified six facial movements shown to have a significant relationship to pain and distress and which have been used to identify pain in various populations. These were:
They defined a combination of these expressions as the "pain/distress gestalt" (a "gestalt" is a combination where the whole is greater than the sum of its parts). In this case, researchers defined this as a pattern of co-ordinated movements that would be viewed by an observer as expressing pain or distress. This "gestalt", they say, is supported by previous research into facial expressions.
Using the coding system, the researchers analysed how often all 19 facial movements occurred simultaneously or within a second of each other. In particular, they wanted to know how often facial expressions included in the “pain/distress gestalt” occurred together.
They used standard statistical methods to analyse their results.
The researchers say the foetuses made “significant progress” towards more complex facial expressions, involving more co-occurring movements, as their gestational age increased. In particular, their analysis of facial movements thought to make up the “pain/distress gestalt” became more complete as the foetuses matured.
For example, at 24 weeks, three of the facial movements identified with pain expression co-occurred in only 5% of the “facial events” while, at 36 weeks, co-occurrence was observed in more than one-fifth (21.2%). However, the co-occurrence of five or more of these facial movements was rare at any age (0% at 24 weeks and 0.5% at 36 weeks).
The researchers say the study shows it is possible for foetuses to show facial behaviours that can be determined as an expression of pain or distress. As the foetus matures, the combination of movements associated with pain or distress increases.
The researchers suggest that rather than indicating pain, the development of these expressions may have a role in preparing the foetus for life outside the womb and the need to alert carers to pain experiences. They theorise that the increasingly complex facial expressions, rather than a sign of distress, are actually a sign of healthy development. As such, the researchers suggest that they could be used to identify normal and abnormal development.
This study contributes to a fascinating field of research – the development of foetal facial expression. However, its conclusion that babies in the womb gradually develop complex facial expressions that indicate pain is based on observations of only a very small number of foetuses. Similarly, the researchers’ hypothesis that babies are “practising” pain/distress expressions for life once they are born remains a theory and one that would be extremely hard to prove.
It is also important to highlight that the study did not show that the unborn babies were actually feeling pain in the womb. The scanning was taking place when the mothers were at rest, in cases of healthy pregnancy, so there would be no particular reason for any of the babies to be in pain or distress.
It is far too soon to say whether, with future research, foetal facial expressions could one day be used to help doctors distinguish between normal and abnormal development.