Can young infants add and subtract?

Three experiments (N = 68), using Wynn's procedure, tested 5-month-old infants' looking time reactions to correct and incorrect results of simple addition and subtraction transformations. The aim was to investigate both the robustness and the parameters of infants' arithmetic competence. Experiments 1 and 2 (N = 44) were replications of Wynn's first two experiments in which infants were shown addition (1 + 1 = 1 or 2) and subtraction (2 - 1 = 1 or 2) requiring imprecise calculation. Experiment 3 (N = 24) was a subtraction counterpart (3 - 1 = 1 or 2) to Wynn's third experiment requiring precise calculation of addition (1 + 1 = 2 or 3). Unlike Wynn, we found no systematic evidence of either imprecise or precise adding and subtracting in young infants. Our results, together with the mix of both positive and negative findings from other studies of infant arithmetic, suggest that infants' reactions to displays of adding and subtracting are variable and, therefore, that infants' numerical competencies are not robust. This conclusion is consistent with previous findings indicating that simple adding and subtracting develops gradually and continuously throughout infancy and early childhood.

The drawbridge phenomenon: representational reasoning or perceptual preference?

Two experiments investigated whether infants would look longer at a rotating "drawbridge" that appeared to violate physical laws because they knew that it was causally impossible, as claimed by R. Baillargeon, E. S. Spelke, and S. Wasserman (1985) and R. Baillargeon (1987a). Using a habituation paradigm, they reported that infants looked longer at a display that appeared impossible (rotated 180 degrees while an obstructing box was behind it) than at one that appeared possible (rotated only 112 degrees, appearing to stop at the box). Experiment 1 eliminated habituation to 180 degree screen rotations. Still, infants looked longer at the 180 degree impossible rotations. Critically, however, infants also looked longer at possible 180 degree rotations in Experiment 2, in which no obstruction was present. Moreover, no difference in effect size was found between the 2 experiments. These findings indicate that infants' longer looking at 180 degree rotations is due to simple perceptual preference for more motion. They question R. Baillargeon's (1987a) claim that it is due to infants' representational reasoning about physically impossible object permanence events.

Mode of delivery in pregnancies complicated by preeclampsia with very low birth weight infants.

The aims of this study were to examine data from an institution at which the goal has been to pursue vaginal delivery in patients with a preterm gestation and preeclampsia and to test the hypothesis that labor does not increase the risk of poor outcome for the preterm infant of a mother with preeclampsia. An analysis of all singleton infants born live who weighed 1500 gm or less and who were born to mothers with preeclampsia or eclampsia from 1975 to 1990 was undertaken. The infants who were delivered by cesarean section without labor and with a reassuring fetal assessment were compared with the infants who went through labor. Of 116 women with singleton pregnancies with preeclampsia and an infant who weighed 1500 gm or less, 54.3% were delivered by cesarean section without labor, 31.0% because of nonreassuring fetal assessment and 23.3% (group 1) because of other indications. Of the patients allowed to labor (group 2), 47.2% had cesarean sections because of fetal intolerance of labor and 32.1% were delivered vaginally. Of the patients who were delivered vaginally, 75% had an unfavorable Bishop's score at the outset of the induction. There was no significant difference between groups 1 and 2 for a number of immediate and long-term outcome variables except for a lower incidence of respiratory distress syndrome in the infants who went through labor. On the basis of these limited data a trial of labor should be considered in carefully selected women with preeclampsia who have very-low-birth-weight infants.

Cost effects of surfactant therapy for neonatal respiratory distress syndrome.

OBJECTIVE: To examine the cost effects of a single dose (5 ml/kg) of a protein-free synthetic surfactant (Exosurf) as therapy for neonatal respiratory distress syndrome, for both rescue and prophylactic therapy. RESEARCH DESIGN: Nonblinded, randomized clinical trials of both rescue and prophylactic therapy. Regression analyses were used to control for the independent effects of sex, multiple birth, delivery method, birth weight, and surfactant therapy. SETTING: The prophylactic trial was conducted at a university medical center only; the rescue trial also included a tertiary community hospital. PATIENTS: Prophylaxis was administered immediately after birth to 36 infants (38 control subjects) with birth weights between 700 and 1350 gm. Rescue therapy was administered at 4 to 24 hours of age to 53 infants (51 control subjects) with established respiratory distress syndrome and birth weights > or = 650 gm (no upper limit). Infants in the prophylactic trial were not eligible for the rescue trial. RESULTS: For the rescue trial, there was a $16,600 reduction in average hospital costs (p = 0.18), which was larger than the cost of the surfactant ($450 to $900), yielding a probable net savings. For the prophylactic trial, hospital costs were larger for treated infants versus control subjects who weighed less than about 1100 gm at birth and lower for treated infants versus control subjects who weighed more than 1100 gm at birth (p < 0.05). For the prophylactic sample, the result was an average cost per life saved of $71,500. CONCLUSIONS: Single-dose rescue surfactant therapy is probably a cost-effective therapy because it produced a lower mortality rate for the same (and probably lower) expenditure. Single-dose prophylactic therapy for smaller infants (< or = 1350 gm) appeared to yield a reduction in mortality rate for a small additional cost. The use of multiple-dose therapy in infants who do not respond to initial therapy may alter the effects described above to either increase or decrease the observed cost-effectiveness of surfactant therapy. Regardless, surfactant therapy will remain a cost-effective method of reducing mortality rates, relative to other commonly used health care interventions.

Initial clinical trial of EXOSURF, a protein-free synthetic surfactant, for the prophylaxis and early treatment of hyaline membrane disease.

EXOSURF is a protein-free surfactant composed of 85% dipalmitoylphosphatidylcholine, 9% hexadecanol, and 6% tyloxapol by weight. A single dose of 5 mL of EXOSURF per kilogram body weight, which gave 67 mg of dipalmitoylphosphatidylcholine per kilogram body weight, or 5 mL/kg air was given intratracheally in each of two controlled trials: at birth to neonates 700 through 1350 g (the prophylactic trial, n = 74) or at 4 to 24 hours after birth to neonates greater than 650 g who had hyaline membrane disease severe enough to require mechanical ventilation (the rescue trial, n = 104). In both studies, time-averaged inspired oxygen concentrations and mean airway pressures during the 72 hours after entry decreased significantly (P less than .05) in the treated neonates when compared with control neonates. Thirty-six percent of the treated neonates in the rescue study had an incomplete response to treatment or relapsed within 24 hours, suggesting the need for retreatment in some neonates. In the rescue trial, risk-adjusted survival increased significantly in the treated group. There were no significant differences in intracranial hemorrhages, chronic lung disease, or symptomatic patent ductus arteriosus between control and treated infants in either trial.

Neonatal status: an objective scoring method for identifying infants at risk for poor outcome.

The likelihood of sustaining neurological, sensory or cognitive deficits is considerably greater for very low birthweight (VLBW) infants who require intensive care in early postnatal life than those without major neonatal illness. Identifying which, if any, medical events are responsible for an adverse outcome is most difficult in the face of multiple concurrent complications. In this research, a principal components analysis was performed in order to arrive at a set of orthogonal variables which succinctly described clinical involvement in the nursery. With this procedure, a single hypothetical factor depicting neonatal status (NS) was computed. Principal component scores were then generated for NS and assigned to 252 VLBW (less than 1500 g) infants. These subjects were followed prospectively from birth to 4 years of age. Standardized measures of neurological, sensory and intellectual function were regularly administered. Neonatal status was shown to be significantly correlated with the various test results and predictive of long-term development. When subjects were divided into quartiles with respect to NS, a specific subgroup was identified as "at high risk" for poor outcome. Those subjects falling into the lower quartile incurred more neurological abnormalities persisting beyond the first year. They also suffered a higher incidence of intracranial hemorrhage and sensori-neural hearing loss. In addition, the lower 25%, as a group, scored well below all others on traditional tests of mental ability. These differences were sustained throughout infancy and early childhood and could not be attributed to a number of demographic variables including sex, gestational age, birthweight, Apgar scores or parental educational level.

Maturation of contralateral brain-stem responses in preterm infants.

Average auditory brain-stem responses (ABRs) evoked by left and right ear stimulation of varying intensities were recorded from ipsilateral and contralateral scalp placements in human neonates. Subjects included pre-term infants, healthy full-term infants and high risk, full-term infants. Pre-term infants were classified into 4 age groups ranging from 29 to 41 weeks post-conceptional age (PCA). Significant ipsilateral/contralateral differences were observed. Further, this effect was highly dependent upon age. The youngest pre-term infants were devoid of contralateral activity despite robust ipsilateral responses. The emergence and evolution of the contralateral wave form could readily be visualized from 31 to 37 weeks PCA. The contralateral response was uninfluenced by stimulus intensity but appeared to be related to the amplitude of the ipsilateral response. No systematic ear differences were noted. Pre-term infants tested between 38 and 41 weeks PCA (term equivalence) showed some persisting immaturity in terms of the ABR. Healthy and sick full-term infants were indistinguishable with respect to ipsilateral or contralateral potentials. On the other hand, very ill 6-week-old infants showed specific contralateral abnormalities.