Children with an unconfirmed but suspected syndromal diagnosis (as established by the clinical geneticist) were included.
At each contact moment, we calculated the standard deviation scores (SDS) for height, weight for height, and head circumference (the latter until 2 years of age), and corrected for ethnicity [10–12]. The Dutch normative data have been collected cross-sectionally in a total of 14,500 children. For Dutch children of Turkish or Moroccan origin, normative data were collected in 2904 and 2880 children of Turkish and Moroccan origin, respectively, living in the largest four cities in the Netherlands. Further, we corrected for prematurity until 2 years of age [10]. Target height (TH) is structurally recorded since January 2011; in earlier years it was recorded on indication only [13]. The target height range (THR) was defined as TH in SDS ± 1.3. A persisting growth problem was defined as two contact moments with SDS heightb−2 or below the THR, and lack of a normal growth at a later contact moment.