C H A P T E R 2 Table 3 gives the differences of weight, height and BMI between the data of van Wieringen and the data of Fredriks for boys and girls at the age of ten years. The differences are calculated for the P3, P50 and P97. The differences are presented as percentage of the original P3, P50 and P97 values of van Wieringen. As an example, in boys the mean height at the P50 of the Fredriks population increased with 3.4 cm which is equivalent to an increase of 2.40%. In addition the weight at the same percentile increased with an average of 2.4 kg. This is equivalent to an increase of 7.60%. The corresponding increase of the BMI of 0.4 kg/m2 is 2.55%. Table 3: Differences of weight, height and BMI at P3, P50 and P97 between the data of van Wieringen and 34 Fredriks for boys and girls. Fredriks (1996-‐1997) – van Wieringen (1964-‐1966) P 3 P 50 P 97 Heightboys + 2.2 cm 1.70 % + 3.4 cm 2.40 % + 4.6 cm 3 % Heightgirls + 3.3 cm 2.97 % + 4.3 cm 3.09 % + 3.8 cm 2.50 % Weightboys + 1.1 kg 0.45 % + 2.4 kg 7.60 % + 5.5 kg 13 % Weightgirls + 1.07 kg 4.40 % + 3.2 kg 10.20 % + 7.4 kg 17 % BMIboys + 0.12 0.80 % + 0.4 2.55 % + 1.2 6.50 % BMIgirls -‐ 0.15 -‐ 1 % + 0.6 3.70 % + 2.2 11.50 % Discussion The increase in weight in children is obvious. Therefore, we examined whether this phenomenon is actually related to the secular trend in height and thereby also in weight, or a phenomenon beyond the expected increase fitting the height. We first examined whether a secular trend already exists during intrauterine growth. To answer these questions, we compared different growth studies, performed in The Netherlands, within a time span of several decades. Prenatal growth studies Comparison of the neonatal curves unexpectedly revealed a lower birth weight in the more recent data in boys born between 26 and 33 weeks and in girls between 25 and 33 weeks. The observed weight difference could be explained by the fact that gynaecologists currently do accept or induce delivery at an earlier gestational age in case of a threatened and/or growth retarded infant. At the time of the Kloosterman study, there was no intervention in such an early stage of pregnancy lacking the modern postnatal medical support. In general, it must be remarked that reference intrauterine growth curves are based on measurements of premature born infants with possibly an abnormal intrauterine growth pattern. Children born at 34 to 39 weeks onwards, no difference in weight is visible, in both boys and girls between 1970 and 2001. Therefore a secular trend in prenatal growth in this time
Proefschrift binnenwerk Manon Ernst_DEF.indd
To see the actual publication please follow the link above