heart tracings have not enhanced predictability (Alirevic, 2017; INFANT Collaborative Group, 2017). Indeed, an abnormal heart rate pattern in fetuses that ultimately develop cerebral palsy may reflect a preexisting neurological abnormality (Phelan, 1994). Because of these studies, the American College of Obstetricians and Gynecologists (20r17 a,d) has concluded that electronic fetal monitoring does not reduce the incidence of long-term neurological impairment. his is discussed further in Chapter 24 (p. 477).
In general, 1-and 5-minute Apgar scores are poor predictors of long-term neurological impairment (American College of Obstetricians and Gynecologists, 2017e). When the 5-minute Apgar score is $3, however, neonatal death or the risk of neurological sequelae rises substantially (Dijxhoorn, 1986; Nelson, 1984). In a Swedish study, 5 percent of such children subsequently required special schooling (Stuart, 2011). In a Norwegian study, the incidence of these low Apgar scores was 0.1 percent in more than 235,000 newborns. lmost a fourth of those with such scores died, and 10 percent of survivors devel oped cerebral palsy (Moster, 2001).
Persistence past 5 minutes of these extremely low scores correlates strongly with a higher risk for neurological morbidity and death (Grtinebaum, 2013). his of course is not absolute, and the 2003 Task Force cited a 10-percent risk for cerebral palsy for infants with 10-minute scores of 0 to 3. For 15-minute scores $2, there is a 53-percent mortality rate and a 36-percent cerebral palsy rate. For 20-minute scores $2, mortality rate is 60 percent, and a cerebral palsy rate is 57 percent. Some outcomes in the Norwegian Study of infants with these low 5-minute Apgar scores are shown in
Table33-3. Survivors who had Apgar scores of 0 at 10 minutes have even worse outcomes. In a review of 94 such newborns, 78 died, and al survivors assessed had long-term disabilities (Harrington, 2007).
TABLE 33-3. Comparison of Mortality and Morbidity in Norwegian Infants Weighing >2500 g According to 5-Minute Apgar Scores
Number 292 233,n500
Neonatal 16.5 0.05 386 (270-552)
Infant 19.2 0.3 76 (56-103) 1-8 yr 3 0.2 18 (8-39)
Cerebral palsy 6.8 0.09 81 (48-128)
Menta I reta rdation 1.3 0.1 9 (3-29)
Other neurological 4.2 0.5 9 (5-17)
As outlined on page 621, objective evidence for metabolic acidosis-cord arterial blood pH <7.0 and base deicit � 12 mmollL-is a risk factor for encephalopathy and for cerebral palsy. he risk accrues as acidosis worsens. From their review of 51 studies, Malin and coworkers (2010) found that low cord arterial pH correlates with greater risk for neonatal encephalopathy and cerebral palsy. When used alone, however, these determinations are not accurate in predicting long-term neurological sequelae (Dijxhoorn, 1986; Yeh, 2012).