Developmental impact of very low birth weight on childhood disability: A parametric and semiparametric binary choice model approach

This paper assesses the effect of birth weight on psychomotor developmental delay of children at the age of 3 years. The developmental delay was diagnosed thought a multidisciplinary evaluation based on Ruth Griffiths' Mental Development scale. To examine the relationship between very low birth weight and possible developmental delay, controlling for sociodemographic and behavior factors, we used four parametric logit models: the general development model, the locomotor's skills development model, the social behaviors development model, and the delays in speech and hearing development. Because the resulting estimates can be highly misleading if the assumed parametric model is incorrect, we used specification tests developed by Horowitz and Hardie (1994) and Fan and Liu (1997), to evaluate if the model fits the data reasonably well. We also used a semiparametric model (Klein and Spady, 1993) to avoid some forms of misspecifications. On the whole, we find that birth weight is strongly associated with developmental delays. Moreover, the probability of a developmental delay for a specific infant also varies with sociodemographic and behavioral factors.