C H A P T E R 2 The neonatal data of the Maastricht University Medical Centre (MUMC) were added, because these data are collected in one specific region. The above-‐mentioned stud-‐ ies are from different regions: Amsterdam and the whole of The Netherlands. The azM registration between 1988 and 2007 is divided in two groups: the first of 1988 which consists of 679 newborns, the second of 2007 consisting of 1,109 newborns, all born at gestational age of 24-‐40 weeks. Unlike the other described studies, these data included length measurements. Therefore, the relation weight to length was evaluated as well. The oldest data from 1988 were compared to the recent ones from 2007. Postnatal growth curves With respect to the postnatal growth the nationwide growth studies, performed in The Netherlands, by van Wieringen and Fredriks were compared8,9. The van Wier-‐ ingen study collected data from a nationwide survey of 55,000 children and adoles-‐ cents between 1964 and 1966. The data pertained to height and weight of respond-‐ ents being recorded at one weekly intervals until 52 weeks and at 26 weekly inter-‐ vals thereafter9. The nationwide study of Fredriks on weight and height was performed from 1996-‐ 1997: a total of 14,500 children, 7,482 boys and 7,018 girls, were included8. Until the age of one year, the measurements were presented in weekly intervals and after the age of one year in yearly intervals. In our study we calculated the BMI, expressed as weight (in kilograms) divided by the squared height (in meters) from the given percentile values of the different studies. We compared the data of the study of van Wieringen (1972) with the more recent data of Fredriks (2004). Results Prenatal growth studies Figure 1 shows the difference between the birth weight data of the neonatal regis-‐ tration from the Kloosterman study in 1970 and the data from the nationwide Peri-‐ natreg study in 2001. The maximal difference between the two studies is 187 grams for boys at gestational age of 29 weeks and 221 grams for girls at gestational age of 31 weeks. In the period before 34 weeks the more recent data show lower birth weights. Because these results were independent of the parity, the mean values of the data of primiparae and multiparae are not presented separately. 28
Proefschrift binnenwerk Manon Ernst_DEF.indd
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