Birth weight charts for a Chinese population: an observational study of routine newborn weight data from Chongqing

Table 1 Expected and observed percentage (n) below selected centiles for validation of the birthweight mathematical model at very preterm, late-moderate preterm, term and all gestational ages

	Very preterm (< 32 weeks)			Late-moderate preterm (32–36 weeks)			Term (> 36 weeks)			All gestational ages (28–42 weeks)
Expected^a	Observed % (n): males (n = 852)	Observed % (n): females (n = 687)	Observed % (n): both sexes (n = 1539)	Observed % (n): males (n = 11,037)	Observed % (n): females (n = 9040)	Observed % (n): both sexes (n = 20,077)	Observed % (n): males (n = 164,513)	Observed % (n): females (n = 152,325)	Observed % (n): both sexes (n = 316,838)	Observed % (n): males (n = 176,402)	Observed % (n): females (n = 162,052)	Observed % (n): both sexes (n = 338,454)
Below 0.4th (0.38%)	0.35	0.58	0.45	0.72	0.73	0.73	0.52	0.56	0.54	0.54	0.57	0.55
Below 2nd (2.28%)	2.35	2.62	2.47	2.84	2.54	2.71	2.34	2.24	2.29	2.37	2.26	2.31
Below 9th (9.13%)	8.22	8.88	8.51	8.82	8.48	8.67	8.06	8.35	8.20	8.11	8.36	8.23
Below 25th (25.24%)	23.12	21.69	22.48	23.90	23.05	23.52	25.19	24.47	24.84	25.10	24.37	24.75
Below 50th (50%)	48.94	49.78	49.32	50.02	50.61	50.29	49.73	50.74	50.22	49.75	50.73	50.22
Below 75th (74.76%)	78.17	78.17	78.17	76.27	76.68	76.46	75.67	75.40	75.54	75.72	75.48	75.61
Below 91st (90.87%)	93.08	92.43	92.79	92.15	91.45	91.84	90.90	91.11	91.00	90.99	91.13	91.06
Below 98th (97.72%)	97.18	97.53	97.34	97.44	97.16	97.32	97.52	97.50	97.51	97.52	97.48	97.50
Below 99.6th (99.62%)	98.94	99.27	99.09	99.24	99.12	99.18	99.46	99.49	99.47	99.44	99.46	99.45

^aCentiles and expected percentages based on 0.67 standard deviation score spacing between centile [15]

ISSN: 1471-2431