Trajectories and predictors of developmental skills in healthy twins up to 24 months of age.
BACKGROUND
Low birth weight and low 5-min Apgar scores have been associated with developmental delay, while older maternal age is a protective factor. Little is known about trajectories and predictors of developmental skills in infant twins, who are generally born with lower birth weights, lower Apgar scores and to older mothers.


METHODS
Developmental skills were assessed at 3, 6, 9, 12, 18 and 24 months using the Ages and Stages Questionnaires in 152 twins from the Birmingham Registry for Twin and Heritability Studies. Multilevel spline and linear regression models (adjusted for gestational age, gender, maternal age) were used to estimate developmental trajectories and the associations between birth weight, maternal age and Apgar scores on developmental skills.


RESULTS
Twins performed worse than singletons on communication, gross motor, fine motor, problem solving and personal-social skills (p < 0.001). Twins caught up around 6 months (score within -1 standard deviation of norm), except on gross motor skills, which did not catch up until after the age of 12 months. A one-year increase in maternal age was significantly associated with decreases in gross motor and personal-social z-scores of up to -0.09, whereas one unit increases in Apgar score increased z-scores up to 0.90 (p < 0.01).


CONCLUSIONS
Healthy twins should be considered at a higher risk for developmental delay. Whether these results are comparable to preterm singletons, or whether there are twin-specific issues involved, should be further investigated in a study that uses a matched singleton control group.
Unit of Urologic and Genetic Epidemiology, Department of Public Health, Epidemiology and Biostatistics, University of Birmingham, United Kingdom; School of Psychology and Speech Pathology, Curtin University, Perth, Western Australia, Australia. Electronic address: cassandra.nan@gmail.com.
Cassandra
C
Nan
Jan
J
Piek
Claire
C
Warner
Diane
D
Mellers
Ruth Elisabeth
RE
Krone
Timothy
T
Barrett
Maurice P
MP
Zeegers
D000328:Adult; D001034:Apgar Score; D001724:Birth Weight; D002657:Child Development / Q000502:physiology*; D003142:Communication; D002658:Developmental Disabilities / Q000175:diagnosis / Q000503:physiopathology; D005260:Female; D005865:Gestational Age; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008423:Maternal Age; D009048:Motor Skills / Q000502:physiology*; D012307:Risk Factors; D014427:Twins
ASQ-3; Ages and Stages Questionnaires-3; BiRTHS; Birmingham Registry for Twins and Heritability Studies; Developmental trajectories; Early development; Longitudinal; Perinatal factors; Twins