Antepartum and Intrapartum Risk Factors Associated with Low One-minute Apgar Score: a Case-control Study

Abstract

Objective: To determine antepartum and intrapartum risk factors associated with low 1-minute Apgar score (≤ 7). A further aim was to develop a predictive model for low Apgar score at 1 minute based on significant risk factors.

Materials and Methods: A case-control study was conducted by including 600 newborns delivered at Vajira Hospital between January 2011 and October 2012. Cases were 200 newborns with 1-minute Apgar score of ≤ 7, while controls were 400 newborns with the score of > 7. Antepartum and intrapartum characteristics were compared between both groups. The independent risk factors were determined by multivariable analysis and were transformed into components of a risk model. The performance of this model was assessed through a receiver-operating characteristic curve analysis.

Results: Complete data of 600 newborns were obtained. By multivariable analysis, four antepartum and intrapartum variables were identified as independent factors associated with low 1-minute Apgar score. These included number of antenatal care, meconium stained amniotic fluid, mode of delivery and low birth weight. The independent variables were integrated into a predictive score which ranged from 0 – 7 points. The optimal cut-off score of ≥ 2 yielded high sensitivity of 74.5% but low specificity of 52.5% for the prediction of low 1-minute Apgar score.    

Conclusion: Low 1-minute Apgar score was significantly associated with number of antenatal care, meconium stained amniotic fluid, operative obstetric deliveries, and low birth weight. The risk model based on antepartum and intrapartum characteristics yielded high sensitivity but low specificity to predict low 1-minute Apgar score.