Table 3. The increment of weight (kg), length (cm) and Ponderal Index (PI) from birth by gender for Tibetan infant (95% Confidence Interval)¹.

	Gender	D1	D2	D3	D4	Fixed effects (β)								Random effects (β)
						Gender	P	Month	P	Gender × Month	P	Birth value	P	Individuals
Weight	Male	1.19(0.95, 1.43)	2.89(3.62, 3.16)	4.61(4.32, 4.90)	6.28(5.97, 6.59)	0.1180	0.6040	1.6900	<0.0001	−0.0019	0.9816	−0.6819	<0.0001	0.8068
	Female	1.09(0.88, 1.31)	2.92(2.64, 3.19)	4.60(4.17, 4.75)	6.28(6.01, 6.56)
Length	Male	4.93(3.79, 6.08)	10.64(9.50, 11.78)	16.73(15.66, 17.81)	23.61(22.39, 24.82)	1.4700	0.0790	6.5271	<0.0001	−0.4408	0.1479	−0.9571	<0.0001	11.2144
	Female	4.61(3.54, 5.67)	10.16(9.07, 11.25)	16.64(15.53, 17.76)	24.23(22.96, 25.49)
PI3	Male	1.07(−0.33, 2.47)	2.50(0.47, 4.53)	1.37(−0.54, 3.29)	0.03(−2.00, 2.05)	0.9321	0.5373	−0.5503	0.4586	−0.4833	0.2988	−0.8710	<0.0001	10.5615
	Female	0.67(−1.76, 3.10)	3.31(0.995, 63)	0.94(−1.26, 3.15)	−2.50(−4.98, −0.01)

¹A mixed model was used here, in which dependent variables were the increments of weight, length or PI from birth and gender and month were fixed variables and interaction between them was included. Individuals were regarded as random variable and weight and length at birth were controlled.

²D1 to D4: the increment of measuring value at the 1^st, 3^rd, 6^th or 12^th month from birth, respectively.

³PI (Ponderal Index) = weight (kg)/length (m)³.