Wednesday January 9 2013
Mothers can overestimate how much pain their babies are in
"Babies with anxious mothers 'feel more pain' during jabs," is today's headline in The Daily Telegraph.
The story comes from a study looking at whether a baby's "pain behaviours" (such as crying and tensing their limbs) during their first immunisation is affected by their mother's mental health or if she is a first-time mother.
Despite The Telegraph's headline, the study did not show any direct association between maternal anxiety (at least, long-term pre-existing anxiety disorder) and infant distress.
It did show that the babies of first-time mothers expressed more "pain behaviours" both before and during the first vaccination than the babies of mothers who have other children.
The researchers speculated that a first-time mother's unfamiliarity with the vaccination process may be picked up by the baby in some way and this causes short-term psychological distress, making them more vulnerable to pain.
The good news for worried mums is that the study also found that all mothers consistently overestimated their baby's pain levels during vaccination – in other words, it did not hurt their baby as much as they thought it did.
And, of course, a quick prick of the skin is nothing compared with the pain associated with preventable conditions such as measles or mumps.
Based on these findings, the researchers have advised that first-time parents are better prepared for infant vaccinations and given more information about the procedure.
Read NHS Choices' Six practical vaccination tips for parents.
Where did the story come from?
The study was carried out by researchers from the University of Durham. There is no information about external funding.
The study was published in the peer-reviewed Journal of Reproductive and Infant Psychology.
The Telegraph's headline claiming that babies with anxious mothers feel more pain during jabs was misleading, depending on how you want to define the term "anxious mother".
The study found that babies of first-time mothers expressed more distress before vaccination, and the authors suggest this may be caused by heightened levels of maternal anxiety immediately before and during the vaccination process.
But no link was found between increased levels of distress and whether the mother had mental health issues, such as anxiety disorder, depression or problems coping with stress.
The research was covered fairly, although uncritically, by the Daily Mail and The Telegraph.
However, again it is probably misleading to talk about the babies "feeling more pain", as both papers did.
The study looked at behavioural signs of distress in the babies and not directly at their pain levels.
Any increase in signs of distress could mainly have been related to psychological, not physical, discomfort.
What kind of research was this?
This was a prospective observational study looking at whether a mother's mental health and if she was a first-time mother had any association with how much distress babies express during their first routine vaccinations at two months of age.
The study also looked at whether the baby's distress was associated with how often they were touched by the mother.
This type of study can only show an association – it cannot show, for example, that a mother's anxiety levels cause her baby to feel more pain.
In this type of study there may be many other factors (called confounders) that affect a baby's expression of distress during vaccination.
The authors point out that vaccinations are a common cause of pain and distress in babies and that early experiences of pain shape an infant's response to later painful events. Maternal levels of stress and depression have previously been found to have a link with infant expression of pain, and research has also indicated that being a first-time mother may be linked to this, but the evidence is still limited.
What did the research involve?
The authors initially recruited 66 mothers and their babies who were attending baby clinics.
All the babies had been assessed as healthy by health visitors, who saw them before the vaccination procedure. Sixteen of the mothers were excluded from the final analysis for various reasons – for example, 13 babies were held during the vaccination by another relative or friend rather than the mother.
Nineteen of the remaining women were first-time mothers.
The mothers and babies were all videotaped during the first routine immunisation at two months of age, which involves two vaccinations.
The researchers measured infant pain levels during the vaccination procedure using a behavioural assessment which looked at levels of crying, facial expression and pain movements (for example, tensing, clenching limbs and flailing).
These behaviours were taped using a HD digital film camera and were studied frame by frame. A composite total pain measure was then calculated. The final infant pain score varied from 0% (no pain behaviours) to 100% (all pain behaviours all of the time).
They also measured and coded maternal touching behaviour such as rubbing, patting, kissing or rocking.
The recordings were studied frame by frame in order to assess the amount of pain babies expressed in the following five phases during the immunisation process:
- 20 seconds before the first vaccination
- during the first vaccination – where the needle entered the skin
- the time between the two vaccinations
- the second vaccination
- 20 seconds after the second needle had been removed
After the vaccination, mothers completed a validated questionnaire which assessed stress immediately after vaccination, and a further questionnaire to assess whether they were depressed.
Researchers used a pain questionnaire to assess how mothers evaluated their babies' pain on a scale of 0 (no perceived pain) to 10 (maximum perceived pain).
They analysed their results using standard statistical methods.
What were the basic results?
Forty-nine mothers completed the study, with an average age of 29 years:
- 23 were stressed
- 7 were depressed
- 1 was both stressed and depressed
The researchers found that:
- babies of first-time mothers showed significantly more pain behaviours before the insertion of the first needle and during the first vaccination than the babies of more experienced mothers
- maternal mental health, stress levels and type of touch had no association with infant pain expression
- all mothers consistently overestimated their babies' pain levels and their assessments were "poorly correlated" with infant pain behaviour
How did the researchers interpret the results?
The researchers say the findings suggest that being a first-time mother may influence infant pain expression before and during the first vaccination, independent of maternal mental health. They suggest that further research, possibly looking at interventions for new parents, is needed.
This is a small study and although it was carefully carried out, its findings should be viewed with caution. As the authors point out, its size means it may not have had the power to detect all differences in infant pain expression. They argue that a larger study incorporating a more balanced sample of mothers and including other racial and ethnic groups is needed. In addition, other factors could have affected how the babies reacted, including their particular mood at the time.
Still, it seems likely that first-time mothers may find their child's first immunisation more difficult and their feelings may be sensed by their babies. It would seem to be helpful if this group was given full information about what happens during immunisation to prepare them for the event ahead of time.
If you are a first-time parent, NHS Choices articles you may find useful include:
Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter.