Maternal influences on infant hand-use during play with toys

Infant hand-use preferences are related to mother's, but not father's, handedness. Since infants match mother's hand-use during toy play, maternal handedness can affect infant hand-use. Twenty-eight mother-infant pairs (14 left-handed and 14 right-handed infants but all right-handed mothers) were videotaped while playing with six toys on the infant's 7-, 9-, and 11-month birthdays. Play was analyzed for five kinds of hand-use biasing situations, but maternal hand-use was the dominant influence. Infant matching of maternal hand-use increased with age and right-handed infants and female infants matched maternal hand-use more frequently. Concordance of hand-use preference between mother and infant seemed to account for both the matching and the stronger preferences of the right-handed compared to the left-handed infants.The research reported in the present study was supported by Grant 1R01 HD 22399-A3 from the NICHHD.     

Physical stimulation reduces the body temperature of infant rats

Physical stimulation of rat pups, of the type normally received from the mother, has been shown to regulate several behavioral and physiological systems in the young. The present paper describes a possible role of physical stimulation in an additional physiological system; the thermoregulatory system. Within a thermoneutral environment, physical stimulation produces a decrease in rectal temperature (Expt. 1). Even in an environment of increasing temperature, similar to that pups experience when in contact with the dam, physical stimulation attenuates an increase in rectal temperature (Expt. 2). The physiological mechanism of heat loss appears to involve ventilatory heat exchange resulting in convective and evaporative heat loss (Expts. 3, 4). Furthermore, physical stimulation continues to produce a decrease in rectal temperature throughout the preweanling period (Expt. 5). These results suggest that pups may not always have to resort to behavioral thermoregulatory mechanisms which require them to separate themselves from their mother. Rather, pups may be cooled, or at least a heat gain attenuated, by physical stimulation from the dam while maintaining contact with her.     

Maternal perception of body size as a determinant of infant adiposity in an African-American community

For 10 weeks, a sample of 105 postpartum African-American clients of three inner-city clinics, were recruited for this nine-month prospective study. Data from 54 mother-infant dyads were used to explore the associations between maternal perceptions of infant body size and the development of adiposity at six- to seven months of age. Correlations, chi-square, paired t-test, ANOVA, and logistic regression analyses were performed. Quantitative assessments of BMI using weight and length measures and qualitative assessments of body size perceptions using questionnaires, silhouette, and ranking scales were conducted. At six- to seven months of age, 40% of the infants were above the 85th percentile and 31% were above the 95th percentile of the NCHS standards for weight for height. Maternal perception of infant body size was positively correlated with early introduction of nonmilk foods. Significantly, more infants perceived as small were introduced to nonmilk foods earlier, compared to infants perceived as average, p=0.03. Additionally, it was observed that the earlier the introduction of nonmilk foods, the greater the infant's BMI at six- to seven months of age (r=0.59, p=0.02). Finally, one-third of mothers were obese with BMI's exceeding 30, and 31.1% were overweight with BMI's between 25 and 30.     

Olfactory influences on the ingestive behavior of infant rats

Twenty-four-hour deprived infant rats from 1 to 12 days of age were exposed to the odor of milk, either by itself or accompanied by oral infusions of water, sucrose, quinine, or milk (Experiment 1). Pups from 3 to 9 days of age became behaviorally active, and mouthed and probed in response to the odor of milk, even in the absence of oral infusions. Six- and 9-day-old pups also increased their intake of various test solutions in the presence of milk odor. This responsiveness to milk odor was not seen in 1-day-old pups, and waned by 12 days of age. Other stimulus odors that were presented in the same context (Experiment 2) failed to elicit such intense behavioral activation, indicating that there was some degree of specificity in the responsiveness to milk odor. Finally, 2 manipulations that influence pups' ingestion of milk, deprivation and ambient temperature, were found to influence pups' responses to milk odor (Experiment 3).     

Maternal diet influences reproductive development in male prairie vole offspring.

The plant compound, 6-methoxy-2-benzoxazolinone (6-MBOA), is found in the meristematic tissue of young, vegetatively growing grasses, and its ingestion stimulates the reproductive system of rodents in both short and long photoperiods. The present study demonstrates the existence of a novel mechanism whereby the presence of 6-MBOA in the diet of pregnant prairie voles (Microtus ochrogaster) enhances gonadal development in their male offspring. Female voles were fed specially milled food in which 6-MBOA was present (50 micrograms of 6-MBOA/g food) or absent (0 microgram of 6-MBOA/g food) prior to the birth of their young; all of these dams received a diet that lacked 6-MBOA/g after the pups were born. Other females were fed food without 6-MBOA throughout pregnancy, but received one of the two diets during lactation. The pups from all experimental groups were weaned at 3 weeks of age and fed thereafter one of the two diets for 3 additional weeks. Prenatal exposure to 6-MBOA enhanced male reproductive development. Maternal ingestion of 6-MBOA during lactation or postweaning intake of 6-MBOA by the young did not influence reproductive development of males. This mechanism may be involved in the rapid rate of sexual maturation observed prior to peak population densities of microtine rodents.     

Maternal separation disrupts the integrity of the intestinal microflora in infant rhesus monkeys.

The integrity of the indigenous microflora of the intestines after maternal separation was investigated in infant rhesus monkeys to determine whether psychological stress may lead to an internal environment conducive to pathogen infection. The stability of the indigenous microflora were estimated by enumeration of total and gram-negative aerobic and facultatively anaerobic bacterial species, specifically Lactobacilli, from coprocultures taken before and after maternal separation. In addition, behavioral and cortisol responses to separation were correlated to the microflora. A significant decrease in fecal bacteria, especially Lactobacilli, was evident on day 3 postseparation, with a return to baseline by the end of the week. The drop in the microflora was correlated with the display of stress-indicative behaviors, but not with cortisol secretion. In addition, infants who displayed numerous stress-indicative behaviors were more susceptible to opportunistic bacterial infection. These results suggest that strong emotional reactions to disruption of the mother-infant bond may increase vulnerability to disease.     

Maternal psychological characteristics as influences on home visitation contact

The current investigation examines how women's psychological characteristics influence their use of home visitation services in programs for mothers and infants in Elmira, New York, and Memphis, Tennessee. Subjects were 99 White (in Elmira) and 207 predominantly African American (in Memphis) first-time mothers. They were recruited during pregnancy and were provided home visitation services by public health nurses until the child's second birthday. In the Elmira trial, variables measuring number of home visits and amount of telephone contact were regressed on a measure of maternal sense of control over life circumstances. Sense of control showed a linear and quadratic relationship to home visitation, with number of visits decreasing as sense of control increased. Phone contact, however, showed a positive linear relationship with sense of control, as did support from partner. In Memphis, similar results were seen with home visitation contact using a measure of psychological resources (comprised of maternal intellectual and mental-health functioning and copying style). These results are interpreted in terms of the nurses varying their contact with families based upon their perception of the mother's need. © 1998 John Wiley & Sons, Inc.     

Maternal melatonin selectively inhibits cortisol production in the primate fetal adrenal gland

We tested the hypothesis that in primates, maternal melatonin restrains fetal and newborn adrenal cortisol production. A functional G-protein-coupled MT1 membrane-bound melatonin receptor was detected in 90% gestation capuchin monkey fetal adrenals by (a) 2-[¹²⁵I] iodomelatonin binding ( K _d, 75.7 ± 6.9 p m ; B _max, 2.6 ± 0.4 fmol (mg protein)⁻¹), (b) cDNA identification, and (c) melatonin inhibition of adrenocorticotrophic hormone (ACTH)- and corticotrophin-releasing hormone (CRH)-stimulated cortisol but not of dehydroepiandrosterone sulphate (DHAS) production in vitro . Melatonin also inhibited ACTH-induced 3β-hydroxysteroid dehydrogenase mRNA expression. To assess the physiological relevance of these findings, we next studied the effect of chronic maternal melatonin suppression (induced by exposure to constant light during the last third of gestation) on maternal plasma oestradiol during gestation and on plasma cortisol concentration in the 4- to 6-day-old newborn. Constant light suppressed maternal melatonin without affecting maternal plasma oestradiol concentration, consistent with no effect on fetal DHAS, the precursor of maternal oestradiol. However, newborns from mothers under constant light condition had twice as much plasma cortisol as newborns from mothers maintained under a normal light–dark schedule. Newborns from mothers exposed to chronic constant light and daily melatonin replacement had normal plasma cortisol concentration. Our results support a role of maternal melatonin in fetal and neonatal primate cortisol regulation.     

Endocrine activation mimics the adverse effects of prenatal stress on the neuromotor development of the infant primate.

Pregnant female rhesus monkeys were exposed to a 2-week period of adrenocorticotropic hormone (ACTH) to determine whether it would affect the early neuromotor development of their fetuses in a manner similar to that observed after psychological stressors. During the first month after birth, infants were tested on two occasions with a modification of the Brazelton Newborn Behavioral Assessment Scale. Infants derived from ACTH-treated pregnancies showed early impairments in motor coordination and muscle tonicity and shorter attention spans as compared to controls. In addition, on a temperament rating scale, infants from the ACTH condition were more irritable and difficult to console. These findings indicate that a delimited period of endocrine activation during pregnancy can have an adverse effect on infant neurobehavioral development, like that of prenatal stress.     

Maternal and sex-related influences on locomotor activity in rats following weaning

The effect of the presence of the mother beyond the normal time of weaning on the locomotor activity of litters is evaluated in the present work. Weaned rats, either females or males, showed a significantly higher activity in the open-field arena than the non-weaned ones. A sex-related difference was also detected. Weaned and nonweaned females showed higher activity than the weaned and nonweaned males, respectively. The androgen-induced lowering of female activity is affected by the presence of the mother. This is substained by the fact that weaned androgenized females exhibited higher levels of activity than nonweaned androgenized females. Our observations suggest that the presence of the mother after the normal time of weaning disturbs the emotional maturation of litters.     

Ovarian influences on primate food intake: Assessment of progesterone actions

Observations during the rhesus menstrual cycle confirmed that adjustments in food intake accompany changes in ovarian condition and indicated progesterone antagonism of estradiol's ability to suppress primate feeding. Food intake was significantly higher during the luteal phase, when progesterone is high and estradiol low, than during the early follicular phase, when levels of both these hormones are low. To test antagonistic effects of progesterone, ovariectomized females given 4 consecutive daily injections of either 15 mg progesterone or vehicle received 20 μg estradiol benzoate on the second and third treatment days. Progesterone did not modify the decline in feeding and body weight which followed this acute estradiol treatment. In an additional study, females chronically stimulated by subdermal estradiol capsules showed no systematic changes in food intake or body weight when injected for 9 days with 15 mg/day progesterone. This treatment did reduce sexual activity during heterosexual mating tests. These females also responded to 15 mg/day dihydrotestosterone propionate with significant weight gains. A fourth study showed that progesterone treatment of 15 mg/day is adequate to raise circulating levels in ovariectomized rhesus above those of intact females. Overall, these studies failed to confirm a role of progesterone in the adjustments of food intake which accompany changes in ovarian condition of primates.     

Opposite effects of gentle handling on body temperature and body weight in rats.

Opposite effects of gentle handling on body temperature and body weight in rats. PHhe aim of this study was to measure the body weight set point when rats are being handled gently and thus experience emotional rise in body temperature. Wistar male rats were used in this experiment, and each rat was its own control. Body weight set point was estimated from the rat's food hoarding behavior. The set point is the intersection of the regression line for hoarding with the X axis. During hoarding sessions the experimenter handled the rat and took its colonic temperature six to eight times, an action sufficient to arouse emotional fever. On alternate days the rats were not handled. Thus, body weight set point was obtained for each rat without handling and with handling. In sessions with handling, rats raised their body temperature, ate less, and defecated more than in control sessions. When handled, the body weight set point declined from 388 +/- 44 g to 366 +/- 47 g (p = 0.048, t = 2,39). The decline in the set point induced by gentle handling is believed to result from an elevation of the hypothalamic CRH.     

Magnetic influences on fetus and infant as reason for sudden infant death syndrome: a new testable hypothesis.

The hypothesis is based upon: a) My observed clustering of Sudden Infant Death Syndrome (SIDS) cases at places with abnormal geomagnetic fields (GMF) and/or electromagnetic fields (EMF); b) recorded GMF with pulsations matching the breathing frequencies of infants; c) the reported immature development of increased dendritic spine density in the brain stem of SIDS cases and; d) the increased dendrite arborization in the brains of rats exposed to magnetic fields (MF). The hypothesis consists of two parts: 1. A disturbed GMF in the residence or surroundings of a pregnant woman may interrupt the normal development of the central organ which controls respiration (brain stem) of the fetus. This is termed the 'Selection Factor'. 2. If such an infant with a functional disturbance of the control organ is then exposed to a GMF or EMF with pulsations similar to his own breathing frequency, but inverted in phase, value, form etc then the vital nerve impulses from the respiration control organ to the breathing organs may be disturbed or blocked with fatal effect. This is termed the 'Trigger Factor'. The elements of the 'Selection Factor' and the 'Trigger Factor' together produce SIDS. A program to test such a supposed 'Trigger Factor' is included.     

Genetic and environmental influences on infant weight and weight change: the Fels Longitudinal Study.

Despite significant progress in understanding the mechanisms by which the prenatal/maternal environment can alter development and adult health, genetic influences on normal variation in growth are little understood. This work examines genetic and nongenetic contributions to body weight and weight change during infancy and the relationships between weight change and adult body composition. The dataset included 501 white infants in 164 nuclear and extended families in the Fels Longitudinal Study, each with 10 serial measures of weight from birth to age 3 years and 232 with body composition data in mid-adulthood. Heritability and covariate effects on weight and weight z-score change from birth to 2 years of age were estimated using a maximum likelihood variance decomposition method. Additive genetic effects explained a high proportion of the variance in infant weight status (h2=0.61-0.95), and change in weight z-score (h2=0.56-0.82). Covariate effects explained 27% of the phenotypic variance at 0-1 month of age and declined in effect to 6.9% of phenotypic variance by 36 months. Significant sex, gestational age, birth order, birth year, and maternal body mass index effects were also identified. For both sexes, a significant increase in weight z-score (>2 SD units) (upward centile crossing) was associated with greater adulthood stature, fat mass, and percent body fat than decrease or stability in weight z-score. Understanding genetic influences on growth rate in a well-nourished, nutritionally stable population may help us interpret the causes and consequences of centile crossing in nutritionally compromised contexts.     

The structure of the perceived sociocultural influences on body image and body change questionnaire

This article is concerned with the development and evaluation of the Perceived Sociocultural Influences on Body Image and Body Change Questionnaire. The scale was designed to assess the perceived nature of feedback received from mother, father, best male friend, and best female friend togain weight, lose weight, and increase muscle tone. The perceived feedback from the media on each of these areas also was assessed. Exploratory factor analysis was conducted with 240 adolescent boys (mean age = 13.83 years) and 204 adolescent girls (mean age = 13.70 years). A 3-factor structure was found for the 4 scales that related to perceived feedback from mother, father, best male friend, and best female friend. Feedback on muscle tone loaded with both weight loss and weight gain. The three factors related to (a) general feedback; (b) encourage, tease, and modeling to gain weight and increase muscle tone, and (c) encourage, tease, and modeling to lose weight and increase muscle tone. The factor structure and the items that made up these factors were the same for both boys and girls for each of the 4 scales. The Perceived Media Influences Scale formed 3 factors for girls. These factors related to gaining weight, losing weight, and increasing muscle tone. For boys, the same 9 items formed a single factor. The same items were retained for boys and girls. A confirmatory factor analysis with 822 adolescents (382 boys, mean age = 14.02 years; 440 girls, mean age = 13.82 years) confirmed the previously described factor structure. These results demonstrate that the Perceived Sociocultural Influences on Body Image and Body Change Questionnaire is able to assess body image and body change strategies that are relevant for both boys and girls.     

Maternal deprivation potentiates pituitary-adrenal stress responses in infant rats

In three experiments we examined the effect of maternal deprivation on the pituitary-adrenal response of 12-, 16- and 20-day-old rat pups to novelty stress. Infant rats were either deprived individually in heated incubators or left in the home nest with their mother and then tested for their corticosteroid response to 30-min exposure to a novel test arena (novelty-stress). In Experiment 1 we showed that the magnitude of the stress response was a positively accelerated function of the deprivation interval. Stress responses were not increased after 1 hour of deprivation, were modestly increased after 8 hours of deprivation, and were dramatically increased after 24 hours of deprivation. In Experiment 2 we asked whether potentiation of the stress response resulted from the maternal or the nutritive components of the deprivation procedure. Pups were tested under one of four treatment conditions formed by a 2 (Maternally Deprived vs. Nondeprived) x 2 (Nutritively Deprived vs. Nondeprived) factorial design. At 12 and 16 days of age, potentiation of the stress response was traced to the absence of maternal care and not nutrients. At 20 days of age, both maternal and nutritive deprivation contributed to the potentiated stress response. The results of Experiment 3 showed that this effect was mediated, at least in part, by increased adrenocortical sensitivity to ACTH, because the corticosteroid response to exogenous ACTH administration was also increased by maternal deprivation. These findings add to a growing body of literature that supports the concept of maternal regulation of infant physiology. They also support previous reports from this laboratory indicating that suppression of the pituitary-adrenal system is modulated by maternal variables during the preweaning period in the rat.     

Maternal touch at 1st contact with the newborn infant

Human mothers have been reported to exhibit a species-characteristic pattern of tactile contact with their newborn infants that begins with fingertip touch of infant extremities and progresses to palmar massaging of the infant trunk. This study presents data on maternal tactile interaction during 10 min of contact following each of 66 deliveries. Most of the women in the study were of Hispanic origin and delivered with midwives in an El Paso, Texas maternity center. Time-sampling techniques were used with tactile behaviors recorded every 10 sec. Most observations began less than 10 min after birth. The statistical analysis revealed that maternal tactile behavior in the 1st 10 min of active interaction is more variable than previously reported. No evidence was offered of a pattern of touch progression: active tactile exploration appeared to vary with the gender of the infant and parity and socioeconomic or sociocultural background of the mother.