Changes in weight, length, head circumference, and ponderal index at birth of healthy term newborns in nine cities in China during the period of rapid social development 1985-2005

•The size of healthy term newborns increased from 1985 to 2005 in nine cities of China by analyzing the second, third, and fourth sets of data from the NSPGDC (National Survey on the Physical Growth and Development of Children in the Nine Cities of China).•There was a larger relative increase in birth weight (BW) than in birth length (BL), and consequently an increase in body proportionality.•Gender difference in birth size was significant and did not change over time.•Regional differences in BW, BL, head circumference (HC) and ponderal index (PI) were significant over the course of the two decades under study.

The changes in the anthropometric parameters at birth of healthy singleton term newborns in nine cities in China were analyzed by means of the data collected in three large-scale cross-sectional physical growth surveys in 1985, 1995, and 2005 (n = 6660, 7109 and 6144). Between 1985 and 2005, average increases in body weight (BW), body length (BL), ponderal index (PI), and head circumference (HC) of newborns were statistically significant: 107 g, 0.2 cm, 0.6 kg/m3 and 0.4 cm, respectively. The relative increase in BW was more than that in BL (3.4% vs 0.4%) in the last two decades, leading to an increase in PI. The distribution of birth size shifted slightly to the right, and the proportion of macrosomia increased from 3.2% in 1985 to 3.4% in 1995 and to 4.3% in 2005. The increases in BW and PI and the increase in rate of macrosomia are concerns from public health perspectives.