[Differences in intrauterine growth levels between full-term neonates born to primiparous or multiparous women]

To establish the intrauterine growth percentile curves of full-term neonates with different gestational ages (GAs) born to primiparous or multiparous women, and to investigate the influence of parity on intrauterine growth potential.

Cross-sectional cluster sampling was performed from April 2013 to September 2015 to measure physical growth in full-term singleton infants with a GA of 37-41 weeks in two hospitals in Shenzhen, China. The Lambda-Mu-Sigma method was used for curve fitting.

The mean values of birth weight, body length, head circumference, chest circumference, and crown-rump length were obtained in 14 529 full-term infants. The 10th, 25th, 50th, 75th, and 90th percentile curves of the five indices were established. The full-term infants born to multiparous women had similar patterns and growth trends of the five percentile curves of the above five indices to those born to primiparous women, while the full-term infants with a GA of 37-41 weeks born to multiparous women had higher mean values and percentile curve values of the above five indices than those born to primiparous women. In the group with a GA of 41 weeks, there was no significant difference in the crown-rump length between the infants born to primiparous women and those born to multiparous women, but there were significant differences in the means of the above five indices in all the other GA groups between the two group infants (P<0.05).

Full-term infants with a GA of 37-41 weeks born to multiparous women have higher intrauterine growth levels of birth weight, body length, head circumference, chest circumference, and crown-rump length than those born to primiparous women, suggesting that parity is an important influencing factor for intrauterine growth potential.