The NICHD Neonatal Research Network's Follow-Up study is a multi-center cohort in which surviving extremely low birth-weight infants born in participating network centers receive neurodevelopmental, neurosensory and functional assessments at 22-26 months corrected age (Infants born prior to July 1, 2012 were seen at 18-22 months corrected age). Data regarding pregnancy and neonatal outcome are collected prospectively. The goal is to identify potential maternal and neonatal risk factors that may affect infant neurodevelopment.

The NICHD Neonatal Research Network's Follow-Up study is a multi-center cohort study in which surviving extremely low birth-weight infants undergo neurodevelopmental, neurosensory and functional assessments at 22-26 months corrected age (Infants born prior to July 1, 2012 were seen at 18-22 month corrected age). The goal of the study is to identify potential maternal and neonatal risk factors that may affect infant neurodevelopment, including:

• Evaluating development of motor skills, cognitive skills, language and behavior
• Determining mortality and the prevalence of specific medical conditions
• Assessing the relationship between growth and neurodevelopmental outcome
• Assessing the relationship between the socioeconomic status and developmental outcome
• Assessing the use of special support services and early intervention programs by this population
• Evaluating the need for follow-up at school age.

The scheduled evaluations collect: demographic information; socioeconomic status; medical history; medications; medical equipment required; growth data; a detailed neurologic examination; Bayley Scales of Infant Development (mental, motor, infant behavior); Child Behavior Checklist.

A sub-study will assess a reference group comprised of a limited number of healthy term infants born in Network centers to meet the following three aims: 1) to avoid potential ascertainment biases due to examiner expectations when only extremely preterm or other high-risk infants are assessed 2) in the absence of well-developed norms for the Bayley Scales, to define thresholds for impairment based on data for a representative sample of healthy children born at term in our centers and concurrently assessed by the same examiners as for our high-risk infants; and 3) to help identify and address when "drift" occurs over time in conducting and scoring Bayley assessments.

• Infants inborn at NRN centers
• <27 weeks gestational age
• Infants enrolled in one or more additional NICHD NRN Follow-up studies. For infants that do not meet the inclusion criteria above, inclusion and exclusion criteria are determined by the criteria for the additional trial(s). In these cases, infants that are larger than 1,000 grams and/or older than 27 weeks may be included in the FU Study.

Note: These inclusion criteria were changed as of 1/1/2008. Prior to this date, infants with birth weights between 401 and 1500 grams who were admitted to NRN NICUs within 14 days of birth were included in the database.

Infants born at 401-1000 grams birth weight and/or <29 weeks gestational age