Eight-Year Follow-up of Cognitive Development in 33 Twin Pairs

Low birth weight as a predictor of adverse health outcomes during adulthood in twins: a systematic review and meta-analysis

BACKGROUND

Low birth weight might affect adverse health outcomes during a lifetime. Our study analyzes the association between low birth weight and negative health outcomes during adulthood in twin populations.

METHODS

Searches were conducted using databases inclusive of MEDLINE, CINAHL, Web of Science, and EBSCO. Observational studies on twins with low birth weight and adverse health outcomes during adulthood were included. Two reviewers independently screened the papers, and a third reviewer resolved the conflicts between the two reviewers. Following abstract and title screening, full-texts were screened to obtain eligibility. Eligible full-text articles were then assessed for quality using a modified Downs and Black checklist. Studies with a score within one standard deviation of the mean were included in the analysis. A fixed-effect model was used for analysis.

RESULTS

3987 studies were screened describing low birth weight as a risk factor for adverse health outcomes during adulthood for all twelve-body systems (circulatory, digestive, endocrine, lymphatic, muscular, nervous, reproductive, respiratory, skeletal, urinary, and integumentary systems). One hundred fourteen articles made it through full-text screening, and 14 of those articles were assessed for quality. Five papers were selected to perform two meta-analyses for two outcomes: asthma and cerebral palsy. For asthma, the meta-analyses of three studies suggested a higher odds of low birth weight twins developing asthma (OR 1.33, 95% CI 1.24-1.44, I2 = 77%). Meta-analysis for cerebral palsy included two studies and suggested a 4.88 times higher odds of low birth weight twins developing cerebral palsy compared to normal birth weight twins (OR 4.88, 95% CI 2.34-10.19, I2 = 79%). We could not find enough studies for other adverse health outcomes to pool data for a Forest plot.

CONCLUSIONS

The odds of low birth weight were found to be high in both asthma and cerebral palsy. There are not enough studies of similar nature (study types, similar body systems) to ensure a meaningful meta-analysis. We recommend that future research considers following up on twins to obtain data about adverse health outcomes during their adult lives.

Why do parents use screen media with toddlers? The role of child temperament and parenting stress in early screen use

Considering child characteristics may be an important piece to understanding parental decision-making for children's screen use. The current cross-sectional study examined the mediating role of maternal parenting stress in the relation of child temperament to young children's screen use. Recognizing the multidimensional aspects of temperament, three mediated pathways for three temperament domains (i.e., negative affectivity, surgency, and effortful control) were tested. Mothers of toddlers, 18-36 months (N = 296), completed an online survey, reporting on child temperament, total parenting stress, and child screen use. The results showed that mother-child dynamics were related to toddlers' screen use. Toddlers' negative affectivity and effortful control were each associated with toddlers' screen use through maternal parenting stress. Higher negative affectivity was associated with higher maternal parenting stress, which in turn, was related to greater screen use in toddlers. Toddlers' lower effortful control was related to higher maternal parenting stress, which in turn, was associated with greater screen use. Toddlers' surgency was not related to either maternal parenting stress or toddlers' screen use. The findings from this study contribute to an understanding of media-related parenting in toddlerhood and may help with the development of strategies for supporting healthy media habits in families with young children.

Twin-singleton differences in neonatal brain structure

Twin studies suggest that global and regional brain volumes are highly heritable. However, estimates of heritability vary across development. Given that all twin studies are open to the potential criticism of non-generalizability due to differences in intrauterine environment between twins and singletons, these age effects may reflect the influence of perinatal environmental factors, which are unique to twins and which may be especially evident early in life. To address this question, we compared brain volumes and the relationship of brain volumes to gestational age in 136 singletons (67 male, 69 female) and 154 twins (75 male, 79 female; 82 DZ, 72 MZ) who had received high resolution MRI scans of the brain in the first month of life. Intracranial volume, total white matter, and ventricle volumes did not differ between twins and singletons. However, cerebrospinal fluid and frontal white matter volume was greater in twins compared to singletons. While gray matter volumes at MRI did not differ between groups, the slope of the relationship between total and cortical gray matter and gestational age at the MRI scan was steeper in MZ twins compared to DZ twins. Post-hoc analyses suggested that gray matter development is delayed in MZ twins in utero and that they experience 'catch-up' growth in the first month of life. These differences should be taken into account when interpreting and designing studies in the early postnatal period.

Parenting stress, infant emotion regulation, maternal sensitivity, and the cognitive development of triplets: a model for parent and child influences in a unique ecology

To examine the development of triplets, 23 sets of triplets were matched with 23 sets of twins and 23 singletons (N=138). Maternal sensitivity was observed at newborn, 3, 6, and 12 months, and infants' cognitive and symbolic skills at 1 year. Triplets received lower maternal sensitivity across infancy and exhibited poorer cognitive competencies compared with singletons and twins. The most medically compromised triplet showed the lowest regulation, received lower maternal sensitivity, and demonstrated the weakest outcomes compared with siblings. Structural modeling charted three levels of influence on cognitive outcomes: direct, indirect, and contextual. The triplet ecology provides a context for assessing the relations among infant inborn dispositions, the rearing environment, and the role of exclusive parenting in development.

Does a triplet birth pose a special risk for infant development? Assessing cognitive development in relation to intrauterine growth and mother-infant interaction across the first 2 years

OBJECTIVE

To examine whether a triplet birth per se poses a risk to the development of infants' cognitive competencies and to the mother-infant relationship.

METHODS

Twenty-three sets of triplets were matched with 23 sets of twins and 23 singleton infants (n = 138) with respect to gestational age, birth weight, and medical and demographic features. Infants with perinatal asphyxia, intraventricular hemorrhage of grade 3 or 4, periventricular leukomalacia, or central nervous system infection were excluded from the study. At 6, 12, and 24 months of age, mother-infant interaction was observed and infants' cognitive development was tested with the Bayley II test.

RESULTS

Mothers of triplets displayed lower levels of sensitivity at 6, 12, and 24 months and infants were less socially involved at 6 and 24 months, compared with singletons and twins. Triplets scored lower than singletons and twins on the Bayley Mental Developmental Index at 6, 12, and 24 months. A weight discordance of >15% was found for 15 triplet sets (65.2%). The discordant triplets showed decreased cognitive skills at 12 and 24 months, compared with their siblings, and received the lowest scores for maternal sensitivity. Hierarchical multivariate regression analysis revealed that greater medical risk at birth, multiple-birth status, lower maternal sensitivity, and reduced infant social involvement in the first 2 years were each predictive of lower cognitive outcomes at 2 years (R2 = 0.33).

CONCLUSIONS

Triplets appear to be at higher risk for cognitive delays in the first 2 years of life, and discordant infants are at especially high risk. This delay is related in part to the difficulty of providing sensitive mothering to 3 infants at the same time. The findings may assist practitioners in guiding prenatal and postpartum parental care and management.

Parent-Infant Synchrony and the Social-Emotional Development of Triplets

To study the social-emotional development of triplets, 23 sets of triplets, 23 sets of twins, and 23 singleton infants (N=138) were followed from birth to 2 years. Maternal depression and social support were assessed in the postpartum period, mother-infant and father-infant interaction and the home environment were observed at 3 months, a separation-reunion episode and a maternal interview were conducted at 12 months, and infant behavior problems were evaluated at 24 months. Lower parent-infant synchrony was observed for triplets. Triplets showed less distress during maternal separation and less approach at reunion. Mothers reported lower adjustment and differentiation among siblings for triplets than for twins. Higher internalizing problems were reported for triplets, and the triplet with intrauterine growth retardation showed the poorest outcomes. Behavior problems were predicted by medical risk, maternal depression, parent-infant synchrony, infant approach, and mother adjustment. Discussion focuses on developmental risk when the exclusivity of the parent-infant relationship is compromised.