Abstract
Objective To externally validate two previously developed prognostic models that predict the
risk for developing metabolic acidosis in newborns using both antepartum (model 1)
and intrapartum (combined with antepartum, model 2) risk factors: parity, previous
cesarean section, maternal diabetes mellitus, gestational age, induced onset of labor,
meconium-stained amniotic fluid, and use of ST analysis.
Study Design The two prediction models were applied in women in active labor at more than 36 gestational
weeks with singleton fetuses in cephalic presentation and with high-risk pregnancies
(n = 5049) who were included in a Swedish randomized trial between December 1, 1998,
and June 4, 2000. The prognostic ability of the models was determined using calibration
and discrimination measures.
Results Of 5049 infants in the validation population, 54 (1.1%) suffered from metabolic acidosis.
After adjustment for incidence differences between the Dutch and Swedish cohorts,
the prognostic models showed good calibration and moderate overall discrimination
(C statistic 0.63, 95% confidence interval [CI] 0.55 to 0.71; and 0.64, 95% CI 0.55
to 0.72), for models 1 and 2, respectively).
Conclusion External validation of the clinical prediction models for metabolic acidosis in Swedish
infants showed good calibration and moderate discriminative ability. Updating of the
models to enhance their predictive abilities seems indicated.
Keywords
metabolic acidosis - external validation - prognostic model - birth asphyxia - neonate
