We recently completed a study of 272,472 live, singleton, term births without congenital anomalies recorded in the Malaysian National Obstetrics Registry (NOR). We wanted to know what proportion of births had a poor 1 minute Apgar score (<4); and the likelihood that they would recover (Apgar score ≥7) by 5 minutes.
As we noted in the paper:
While the Apgar score at 5 minutes is a better predictor of later outcomes than the Apgar score at 1 minute, there is a necessary temporal process involved, and a neonate must pass through the first minute of life to reach the fifth. Understanding the factors associated with the transition from intrauterine to extrauterine life, particularly for neonates with 1 min Apgar scores <4, has the potential to improve care.
Surprisingly, to me at least, we could find no research looking at that 1 minute to 5 minute transition. Ours was a first.
From the 270,000+ births, you can see (Figure 1) that the probability of a 5 minute Apgar score ≥7 rises dramatically as the 1 minute Apgar score increases. There is an almost straight line relationship between a 1 minute Apgar score of 1, a 1 minute Apgar score of 6, and the chance of a 5 minute Apgar score ≥7.
Fig 1: The probability (with 95% CI) of an Apgar score at 5 min (≥7) given any Apgar score at 1 minute
A 1 minute Apgar of 6 almost guarantees a 5 minute Apgar score ≥7; in contrast a 1 minute Apgar of 3 has only a 50% chance of recovery, and a 1 minute Apgar of 1 has only less than a 10% chance of recovery.
Fortunately, only 0.6% of births had poor Apgar scores (<4). The type of delivery (Caesarean section, or vaginal delivery) and the staff conducting the delivery (Doctor or Midwife) were both significantly associated with the chance of recovery. The challenge is working out the causal order. Do certain kinds of delivery cause poor recovery, or are babies likely to have poor recovery delivered in particular ways? Does the training of Doctors or Midwives exacerbate/improve the risks of poor recovery, or are babies likely to have poor recovery delivered by particular personnel?
Our study cannot answer the questions, but it does raise interesting points for future studies of actual labor room practice — questions not easily answered with registry type data.