Father involvement and cognitive/behavioral outcomes of preterm infants

OBJECTIVE

To assess the independent effect of father involvement on intellectual and behavioral outcome of 985 low birth weight preterm infants followed longitudinally from birth to age 3 years as part of the Infant Health and Development Program.

METHOD

The sample for this study is drawn from eight urban sites, composed largely of ethnically diverse and relatively disadvantaged families. On the basis of a combined score for father's stable presence in the home and amount of play with the infant, we defined extreme groups of high-involvement fathers (33%, n = 305) and low-involvement fathers (16%, n = 148), with the remainder as a middle group (51%).

RESULTS

Most fathers played a meaningful role as play partner with their high-risk infants. Approximately 75% of fathers were reported to play with the baby every day at 12 (peak), 24, and 36 months. Fathers who were black, younger, had teenage mothers as companions, or were from low-income families were less involved with their infants. For black fathers, low family income was significantly associated with low father involvement. Within the black ethnic subgroup only, higher father involvement was associated with improved cognitive outcome. Mean IQ for the high-involvement subgroup was 6.00 points higher than for the low-involvement group even after adjusting for family income, neonatal health, treatment group status, and paternal age.

CONCLUSION

Father involvement enhances cognitive outcome in black families and may have implications for intervention.

Growth status and growth rates of a varied sample of low birth weight, preterm infants: a longitudinal cohort from birth to three years of age

To obtain follow-up growth data on a large sample of low birth weight, preterm infants, 985 infants were monitored longitudinally in an eight-site collaborative program until 3 years of age, corrected for prematurity. The growth of 608 of these infants was described previously through 1 year of age. In the full sample, 149 infants weighed less than or equal to 1250 gm at birth, 474 between 1250 and 2000 gm, and 362 between 2000 and 2500 gm. Thirty-three percent were white, 53% were black, and 11% were Hispanic. Weight, length, and head circumference were measured at birth and at 40 weeks and 4, 8, 12, 18, 24, 30, and 36 months gestation-corrected age in at least 862 infants each time. Descriptive statistics and estimated growth rates for all growth variables and a body mass index (height in kilograms per square meter), plotted by sex and birth weight group, demonstrated growth patterns lower than published standards for term infants of the same age and sex. These patterns of growth differed by birth weight group. Little catch-up was noted by the 36-month examination for gestation-corrected age for any birth weight group. We conclude that low birth weight, preterm infants have different patterns of growth than term infants during the first 3 years of life, even with plotting corrected for gestational age.

Growth patterns of low birth weight preterm infants: a longitudinal analysis of a large, varied sample

To obtain growth data on a large sample of low birth weight preterm infants, we monitored 608 infants longitudinally in an eight-site collaborative program. Ninety-nine infants weighed less than or equal to 1250 gm at birth, 289 between 1250 and 2000 gm, and 220 infants between 2000 and 2500 gm. Thirty-four percent were white, 52% black, and 14% Hispanic. Weight, height, and head circumference were measured at birth and at 40 weeks and 4, 8, and 12 months of gestation-corrected age on at least 553 infants each time. Descriptive statistics for all growth variables and a body mass index (kilograms per square meter), plotted by sex and birth weight group, demonstrated growth patterns lower than published standards for term infants of the same age and sex. These patterns of growth differed by birth weight group. No catch-up growth was noted by the 12-month examination (gestation-corrected age) for any birth weight group. We conclude that low birth weight preterm infants have different patterns of growth than term infants during the first year of life, even with plotting corrected for gestational age.

Identification of intrauterine growth retardation among low birth weight preterm infants

This study describes an attempt to define intrauterine growth retardation low birth weight preterm infants by comparing reference standards for intrauterine growth in weight, length, and head circumference on their variability across ethnic groups and cities, and on their specificity in independently classifying infants as short, thin, or having small heads. The sample consisted of 985 inborn preterm low birth weight infants enrolled at eight participating sites in a randomized clinical trial using uniform sampling criteria. When gestational age was used as the reference standard, striking differences were found by ethnicity and site in the prevalence of low weight infants at birth. These differences, as well as the potentially false overlap of classification, were attenuated when the use of gestational age as a reference standard was used only for birth length, while length itself was used (as an alternative to gestational age) as the reference standard for birth weight, and weight was used as the reference standard for head circumference. These results raise questions about the use of gestational age as the primary or only reference standard in assessing weight and head circumference at bith.

Nutrients, neurotransmitters and infant behavior

In recent years, short-term effects of the composition of each meal on the synthesis of brain neurotransmitters have been studied. This paper reviews studies of the influence of dietary precursors such as tryptophan and other competing amino acids on serotonin synthesis and metabolism and emphasizes the important influence of insulin. The paper then focuses on assessment of newborn state behavior, since evidence in adult humans has suggested a relationship between sleep behavior and brain serotonin levels. Several studies are then summarized. First, a study of healthy full-term newborns examining the relationship between diet and sleep behavior showed that infants fed tryptophan entered active and quiet sleep sooner than infants fed valine and low carbohydrate. Other studies designed to examine the influence of hyperinsulinemia on this system are then described. An observational study of newborns of diabetic mothers during the first weeks of life showed that they were quieter babies, with difficulties in visual orientation and motor performance. Plasma amino acid ratios studied during a glucagon-stimulation test in an infant with hyperinsulinemia showed a marked increase in parallel with changes in insulin levels. The results suggest that infant sleep behavior can be a sensitive dependent variable in studies of behavioral effects of diet and suggests that variations in serotonin levels may play a modulating role.

Diet and sleep patterns in newborn infants

Sleep behavior is modulated by serotonergic neurons within the brain, and the synthesis and release of serotonin by such neurons is thought to be influenced by the availability of tryptophan, the amino acid precursor of serotonin. We investigated the effects on the sleep patterns of newborn infants of variations in diet designed to affect tryptophan availability. Twenty healthy newborns (two to three days of age) were randomly assigned to receive a feeding consisting either of tryptophan in 10 per cent glucose or valine in 5 per cent glucose (valine competes with tryptophan for entry into the brain). Sleep patterns during the three hours after this feeding were compared with those after a feeding of routine formula (Similac). The infants fed tryptophan entered active sleep 14.1 minutes sooner than they did after Similac, and entered quiet sleep 20 minutes sooner. Those fed valine entered active sleep 15.8 minutes later than they did after Similac, and entered quiet sleep 39 minutes later. The differences between the tryptophan and valine groups were significant (P less than 0.01 for active sleep and P less than 0.005 for quiet sleep). We conclude that variations in the composition of the diet may influence sleep behavior in newborns.

Behavioral and cardiac rhythmicity during mother-father-stranger infant social interaction

In an effort to understand the temporal organization of infant physiologic and behavioral systems during social interaction with adults, spectral and cross-spectral analyses of infant heart rate and mother-father-stranger-infant behavioral data are described herein for a 3-month-old infant during face-to-face social interaction with her parents and a stranger. This infant's heart rate rhythms were stronger during social interaction with both mother and father than with a stranger. Infant behavioral rhythms were associated with (high coherence) the parents' behavioral rhythms, but not with those of the stranger. Furthermore, infant heart rate and infant behavioral rhythms showed high coherence with all three adults. Although these findings are preliminary, based on a case study and need replication, they generate intriguing hypotheses. This technique of studying the rhythmicity of infant social interaction with spectral analysis suggests that the 3-month-old infant's behavior and heart rate are synchronized during interaction with all three adults; however, the infant and adult behavioral rhythms are synchronous only with mother and father and not with an unfamiliar stranger.

Perinatal characteristics of newborns relinquished at birth

Demographic, perinatal, and newborn characteristics of single mothers relinquishing their newborns for adoption (N = 111) were compared with randomly selected and matched groups of mothers keeping their infants. Relinquishing mothers were younger, more apt to be Caucasian, Catholic, primiparous, and economically independent of government assistance, less likely to plan their pregnancies, and later starting prenatal care. In general, their pregnancies and infants were at no higher neonatal risk than those of other single mothers.

Assessing effects of serotonin precursors on newborn behavior

While traditional studies of newborn diet have focused on the effects of malnutrition on the central nervous system, there is now interest in how qualitative differences in the composition of early newborn feeding might influence behavior. This paper reviews the available techniques for assessing newborn perception and cognition, as well as behavioral organization. The paper then focuses intensively on measures of newborn state behaviour in view of evidence in adult humans, as well as in non-human species, suggesting a relationship between sleep behavior (sleep onset, night waking) and brain serotonin levels. A study designed to examine the relationship between dietary precursors of brain serotonin (within the range of concentrations found in human milk) and newborn state behavior after feeding is described to illustrate the application of these techniques. Healthy, fullterm newborns were fed a modified formula, containing tryptophan or valine, on one day, a routine formula on another day, and observed continuously for 3 h after each feeding for the observation and recording of newborn state. Data from individual infants in the tryptophan and valine groups are presented to illustrate the findings that infants fed tryptophan entered quiet sleep and active sleep sooner than infants fed valine and spent more time in active sleep and less time alert. These results illustrate the value of newborn behavior as a sensitive dependent variable in studies of behavioral effects of diet and suggests that variations in serotonin levels in the newborn brain may modulate the newborn's sleep/wake behaviour.