Secular change in size at birth from 1973 to 2003: national data from Denmark.
OBJECTIVE
To explore whether birth weight (BW) has been increasing in Denmark at the same level as in other countries and whether this increase is paralleled by an increase in birth length (BL) or whether body proportionality, expressed as ponderal index (PI), has changed.


METHODS
This study used data analysis of information from The Danish Medical Birth Registry including all single live births in Denmark from 1973 to 2003 (n = 1,863,456). BW, BL, gestational age, maternal age, and smoking status (only from 1991 on) were measured.


RESULTS
Mean BW increased steadily during the period (160 grams; equivalent to approximately 5 g/yr) at a rate higher than that reported from other countries. BL showed only a minor increase (2.4 mm), leading to an increase in PI (0.8 kg/m3) during the period. Controlling for the effect of increasing maternal age and decreasing gestational age and maternal smoking prevalence (only data after 1991), there was still an increase in BW of approximately 4 g/yr.


CONCLUSIONS
During the last 30 years, neonates have become bigger, with a larger relative increase in BW than BL, leading to an increase in PI. The increasing BW and PI, which may be caused by increased maternal weight, could further promote the obesity epidemic.
Schack-Nielsen
Lene
L
Department of Human Nutrition and Centre for Advanced Food Studies, The Royal Veterinary and Agricultural University, Frederiksberg C, Denmark. lsn@kvl.dk
Mølgaard
Christian
C
Sørensen
Thorkild I A
TI
Greisen
Gorm
G
Michaelsen
Kim F
KF
D000328:Adult; D000886:Anthropometry; D001724:Birth Weight; D001827:Body Height / Q000502:physiology; D001835:Body Weight / Q000502:physiology; D003718:Denmark; D005260:Female; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D008423:Maternal Age; D009765:Obesity / Q000453:epidemiology / Q000209:etiology*; D012907:Smoking