Their call comes in the light of findings that suggest Apgar scores currently considered “within the normal range” are linked to higher risks of illness and death.
“Our findings provide strong evidence to support the proposition that the optimal Apgar score is 10 at each time point”
Even a small change in score from five to 10 minutes after birth may have an impact, said the Swedish researchers in the British Medical Journal.
Specifically, they found Apgar scores of 7, 8, and 9 – considered to be within the normal range – are associated with higher risks of illness and even death in newborns.
The odds of problems are increased with “normal” scores less than 10, but the researchers stressed that the risk was still low and certainly lower than for babies with scores outside of normal range.
They highlighted that the Apgar score was a quick and simple way to assess a baby’s condition at birth.
It involves assessment on a scale from zero to two at one, five and 10 minutes after birth using five simple criteria – complexion, pulse rate, reaction when stimulated, muscle tone, and breathing.
The five values are then added up to obtain an overall score from zero to 10.
Scores of less than seven are considered low and are known to carry higher risks of infections and breathing problems, as well as long term conditions such as epilepsy and cerebral palsy.
However, scores of 7 to 10 are traditionally considered to be “within the normal range” and therefore reassuring.
But the Swedish researchers said that no study had previously investigated whether normal scores of 7, 8, or 9 were associated with greater risk of illness or death than a perfect score of 10.
As a result, the team, led by Dr Neda Razaz at the Karolinska Institutet, compared associations between Apgar scores of 7, 8, and 9 – versus 10 – with illness and death in newborns.
They analysed data from more than 1.5 million Swedish infants born at full term between 1999 and 2016.
“All newborns should be assigned an Apgar score at 10 minutes, regardless of their score at one and five minutes”
Infants with Apgar scores of 7, 8, and 9 at one, five, and 10 minutes after birth were compared with those with an Apgar score of 10 at one, five, and 10 minutes after birth.
The researchers found that scores of 7, 8 and 9 at one, five, and 10 minutes were strongly associated with higher risk of infections, breathing problems, brain injury as a result of oxygen deprivation, low blood sugar levels, and death compared with a score of 10.
For example, compared with a one-minute Apgar score of 10, a one-minute Apgar score of 9 was associated with a 1.5-fold higher odds of infections (0.8 versus 0.5 per 100 births).
At five and 10 minutes, the odds were progressively larger: 2.1-fold (1.7 versus 0.7 infections per 100 births) at 5 minutes, and 3.3-fold (2.9 versus 0.8 infections per 100 births) at 10 minutes.
A small change in Apgar score from 10 at five minutes to 9 at 10 minutes was also associated with increased risk, compared with a stable score of 10 at five and 10 minutes, said the researchers.
They said their study showed that low scores within the normal range were “strongly associated with neonatal mortality and morbidity and that these associations are substantially stronger with increasing time after birth”.
They stated: “Our findings provide strong evidence to support the proposition that the optimal Apgar score is 10 at each time point, and all newborns should be assigned an Apgar score at 10 minutes, regardless of their score at one and five minutes.”