A recent study of term infants in Sweden sought to measure the relationship between Apgar scores of 7 to 9 and neonatal mortality and morbidity.
Before we jump into the findings of this new study, let’s talk about what an Apgar score of 7 to 9 means for an infant.
Apgar scores are the standard simple method for quickly assessing newborn vital signs. This scoring system was created by Dr. Virginia Apgar in 1952 (1). Medical professionals later developed an acronym using the word “Apgar” to show the criterion included in the assessment:
A: Appearance (skin color)
P: Pulse (heart rate)
G: Grimace (reflex irritability/response)
A: Activity (muscle tone)
R: Respiration (breathing ability)
In order to give an Apgar score, the medical professionals score the five criteria above as 0, 1, or 2, with 2 being the best score. The total Apgar score is calculated by adding all five scores together. Apgar scores are generally taken at 1 minute, 5 minutes, and 10 minutes after birth.
Apgar scores of 0-3 are critically low, especially in term or late-preterm infants. Apgar scores of 4-6 are below normal, and mean that the baby will likely be in need of medical intervention. Apgar scores of 7-10 are considered normal.
When the baby has an Apgar score of 7-10, they will likely only require the routine postnatal care (2).
Researchers obtained data from the Medical Birth Register for singleton live births in Sweden between 1999 and 2016 (3). The study excluded preterm infants, infants with records missing information on infant and maternal identification, infants with major congenital malformations, and infants whose records did not provide Apgar scores at 1, 5, and 10 minutes.
The population study was able to focus on the 1,551,436 infants with Apgar scores of 7-10 at 1, 5, and 10 minutes.
Infant mortality for this study was defined as infant death between 0-27 days after birth. Neonatal morbidity was defined as asphyxia-related neonatal complications (such as hypoxic-ischemic encephalopathy, or HIE), respiratory distress, neonatal hypoglycemia, and neonatal infections found between 0-27 days after birth.
The study found the following results:
- 11% of infants had Apgar scores of 10 at 1 minute
- 89% of infants had Apgar scores of 10 at 5 minutes
- 97% of infants had Apgar scores of 10 at 10 minutes
Other key findings of the study included:
- Adjusted odds ratios, or relative odds of something occuring, for neonatal mortality, asphyxia-related complications, neonatal infections, neonatal hypoglycemia, and respiratory distress were higher among infants with lower Apgar scores compared to infants with Apgar scores of 10.
- Adjusted odds ratios for respiratory distress for an Apgar score of 9 versus 10 were 2.0 at 1 minute, 5.2 at 5 minutes, and 12.4 at 10 minutes. It was thus more likely for respiratory distress to occur for those with an Apgar score of 9, especially as time went on and the Apgar score remained at 9.
- The adjusted rate difference for respiratory distress was 9.5% for an Apgar score of 9 at 10 minutes compared to an Apgar score of 10 at 10 minutes.
- The adjusted rate difference for respiratory distress was 41.9% for an Apgar score of 7 at 10 minutes compared to an Apgar score of 10 at 10 minutes.
- A reduction in Apgar score from 10 at 5 minutes to 9 at 10 minutes was associated with higher odds of neonatal morbidity compared with a stable Apgar score of 10 at both times.
What do these results mean?
This study demonstrated that risks of neonatal mortality and morbidity were both higher among non-malformed term infants with lower Apgar scores. It also revealed that these risks were higher in non-malformed term infants whose Apgar scores lowered between the 5 and 10 minute marks.
Previous studies have established a connection between Apgar scores of 7 and below and adverse outcomes. This recent study shows that many adverse outcomes are also associated with Apgar scores in the 7-9 range, especially when compared to adverse outcomes in infants who have been given an Apgar score of 10 and who have maintained that Apgar score for 10 minutes.
- Women’s Health Care Physicians. (n.d.). Retrieved from https://www.acog.org/Clinical-Guidance-and-Publications/Committee-Opinions/Committee-on-Obstetric-Practice/The-Apgar-Score.
- APGAR Test: What do the Scores Mean? (2015, December 07). Retrieved May 28, 2019, from https://americanpregnancy.org/labor-and-birth/apgar-test/
- Razaz, N., Cnattingius, S., & Joseph. (2019, May 07). Association between Apgar scores of 7 to 9 and neonatal mortality and morbidity: Population based cohort study of term infants in Sweden. Retrieved May 28, 2019, from https://www.bmj.com/content/365/bmj.l1656