Page 31 - Sample Moderate prematurity, socioeconomic status, and neurodevelopment in early childhood

Prevalence of behavioural and emotional problems
METHODS
Study design
The “Longitudinal Preterm Outcome Project” (Lollypop) is a large prospective
cohort study designed to investigate the growth, development, and general health
of children born preterm, with a special focus on MP children.19 The Lollypop
cohort consists of a community-based sample of MP children (all born between 32
and 36 weeks’ gestation), and a random sample of term-born children. At the stage
in which the study was designed, MP children concerned those children born at
32-35 weeks gestation and therefore children born at 360-366 weeks gestation were
not included. Parents completed the questionnaire on behavioural and emotional 3 problems just before the scheduled Preventive Child Health Care (PCH) visit at
four years of age. The study was approved by the local institutional review board.
Population
The study children were sampled in 13 randomly selected PCH centres, which together monitored 45,446 children. This concerns 25% of all children of this age monitored by PCH centres. In the Netherlands 90-95% of children are seen regularly by PCH centres for well-child care from birth up to age four, free of charge.20 Guidelines of the National Centre for PCH (www.ncj.nl) are being used for monitoring in the PCH centres. Each PCH centre provided a sample of all preterm children born during one year, either from January 2002 to January 2003 or from June 2002 to June 2003. Term-born children were sampled from the same PCH centres and were in the same age range as the preterm children. After the file of each second preterm child had been drawn, the first subsequent file of a term-born child was drawn to serve as a control. Exclusion took place if a child had a congenital malformation or syndrome and if the gestational age could not be verified. For this study children born at less than 32 weeks of gestation were also excluded. Gestational age was calculated by using the last date of menstruation, and confirmed by early ultrasound measurements in >95% of cases. Parents were willing to participate for 995 (86.9%) of the MP and 577 (85.6%) of the term-born children. Response rates on the behavioural questionnaire were high: the parents of 93.3% of MP and 95.1% of term-born children returned the questionnaires.
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