Table 6.
Comparison of growth parameters between/among subgroups of important associated variablesa
| PMA at birth | Sex | Number of fetus | Intrauterine growth status | |||||||
|---|---|---|---|---|---|---|---|---|---|---|
| 34 weeks (N = 99) | 35 weeks (N = 173) | 36 weeks (N = 327) | Female(N = 262) | Male(N = 337) | Singleton(N = 449) | Twin (N = 150) | SGA (N = 30) | AGA (N = 546) | LGA (N = 23) | |
| PMA at birth | – | – | – | 35.34 ± 0.77 | 35.42 ± 0.74 | 35.39 ± 0.75 | 35.34 ± 0.75 | 35.43 ± 0.73 | 35.37 ± 0.76 | 35.65 ± 0.65 |
| Male, N(%) | 51 (51.5) | 95 (54.9) | 191 (58.4) | – | – | 266 (59.2) | 71 (47.3)κ | 21 (70.0) | 304 (55.7) | 12 (52.2) |
| Twin, N(%) | 25 (25.3) | 49 (28.3) | 76 (23.2) | 79 (30.2) | 71 (21.1)ε | – | – | 11 (36.7) | 139 (25.5) | 0 (0)ƭƞ |
| SGA, N(%) | 4 (4.0) | 9 (5.2) | 17 (5.2) | 9 (3.4) | 21 (6.2) | 19 (4.2) | 11 (7.3) | – | – | – |
| AGA, N(%) | 93 (93.9) | 160 (92.5) | 293 (89.6) | 242 (92.4) | 304 (90.2) | 407 (90.6) | 139 (92.7) | – | – | – |
| LGA, N(%) | 2 (2.0) | 4 (2.3) | 17 (5.2) | 11 (4.2) | 12 (3.6) | 23 (5.1) | 0 (0)κ | – | – | – |
| Maternal age | 29.72 ± 3.26 | 30.93 ± 4.13* | 30.72 ± 4.02* | 30.76 ± 3.95 | 30.50 ± 3.96 | 30.62 ± 4.15 | 30.59 ± 3.29 | 29.00 ± 2.48 | 30.59 ± 3.95ƭ | 33.35 ± 4.21ƭƞ |
| Birth Length(cm) | 45.59 ± 2.14 | 46.93 ± 1.96* | 48.09 ± 1.94*§ | 47.14 ± 2.13 | 47.50 ± 2.22ε | 47.54 ± 2.24 | 46.75 ± 1.90κ | 44.55 ± 2.32 | 47.36 ± 2.00ƭ | 50.44 ± 1.53ƭƞ |
| Birth Weight(kg) | 2.29 ± 0.32 | 2.51 ± 0.36* | 2.78 ± 0.40*§ | 2.56 ± 0.41 | 2.67 ± 0.42ε | 2.67 ± 0.44 | 2.47 ± 0.32κ | 1.95 ± 0.25 | 2.61 ± 0.33ƭ | 3.73 ± 0.36ƭƞ |
| Birth LengthZ | 0.22 ± 0.84 | 0.27 ± 0.78 | 0.26 ± 0.79 | 0.35 ± 0.75 | 0.18 ± 0.82ε | 0.32 ± 0.80 | 0.05 ± 0.76κ | −0.93 ± 0.83 | 0.27 ± 0.72ƭ | 1.38 ± 0.58ƭƞ |
| Birth WeightZ | −0.07 ± 0.78 | −0.12 ± 0.82 | −0.04 ± 0.88 | −0.03 ± 0.84 | −0.09 ± 0.85 | 0.03 ± 0.88 | − 0.37 ± 0.67κ | −1.73 ± 0.44 | −0.07 ± 0.63ƭ | 2.19 ± 0.61ƭƞ |
| PMA at visit(week) | 40.00 ± 0.70 | 40.67 ± 0.73* | 41.19 ± 0.91*§ | 40.78 ± 0.96 | 40.89 ± 0.92 | 40.86 ± 0.94 | 40.79 ± 0.92 | 40.85 ± 0.92 | 40.84 ± 0.94 | 40.81 ± 0.90 |
| Term-corrected Length(cm) | 51.54 ± 1.95 | 52.60 ± 2.11* | 53.51 ± 2.19*§ | 52.41 ± 2.17 | 53.32 ± 2.23ε | 53.08 ± 2.33 | 52.46 ± 1.90κ | 50.41 ± 2.09 | 52.95 ± 2.13ƭ | 55.64 ± 1.71ƭƞ |
| Term-corrected Weight (kg) | 3.72 ± 0.54 | 3.94 ± 0.55* | 4.18 ± 0.59*§ | 3.88 ± 0.58 | 4.15 ± 0.58ε | 4.08 ± 0.62 | 3.89 ± 0.49κ | 3.29 ± 0.59 | 4.03 ± 0.54ƭ | 5.03 ± 0.44ƭƞ |
| Term-corrected LengthZ | 0.27 ± 0.91 | 0.46 ± 0.89 | 0.67 ± 0.90*§ | 0.54 ± 0.89 | 0.55 ± 0.92 | 0.59 ± 0.95 | 0.39 ± 0.78κ | −0.62 ± 0.82 | 0.55 ± 0.85 | 1.78 ± 0.68 |
| Term-corrected WeightZ | 0.35 ± 1.03 | 0.47 ± 0.96 | 0.70 ± 0.99*§ | 0.49 ± 0.96 | 0.65 ± 1.02 | 0.64 ± 1.04 | 0.38 ± 0.82κ | −0.98 ± 1.02 | 0.59 ± 0.86ƭ | 2.34 ± 0.64ƭƞ |
| ΔLengthZ | 0.04 ± 0.90 | 0.20 ± 0.86 | 0.41 ± 0.75*§ | 0.19 ± 0.83 | 0.36 ± 0.80ε | 0.27 ± 0.82 | 0.34 ± 0.82 | 0.30 ± 0.76 | 0.28 ± 0.82 | 0.40 ± 0.92 |
| ΔWeightZ | 0.42 ± 0.77 | 0.58 ± 0.74 | 0.74 ± 0.68*§ | 0.52 ± 0.70 | 0.74 ± 0.72ε | 0.61 ± 0.75 | 0.75 ± 0.61κ | 0.75 ± 0.84 | 0.66 ± 0.71 | 0.15 ± 0.60ƭƞ |
| Adjusted ΔLengthZ# | 0.10(−0.07, 0.27) | 0.22 (0.10, 0.34) | 0.38 (0.29, 0.47)*§ | 0.20(0.10, 0.30) | 0.35 (0.27, 0.44)ε | 0.26 (0.19, 0.34) | 0.36(0.23, 0.49) | 0.23(−0.06, 0.52) | 0.28 (0.22, 0.35) | 0.45 (0.11, 0.78) |
| Adjusted ΔWeightZ# | 0.55 (0.41, 0.70) | 0.60 (0.50, 0.71) | 0.70 (0.62, 0.78) | 0.53 (0.45, 0.62) | 0.73 (0.66, 0.81)ε | 0.61 (0.54, 0.67) | 0.76 (0.65, 0.87)κ | 0.70 (0.45, 0.95) | 0.66 (0.60, 0.72) | 0.18(−0.11, 0.46)ƭƞ |
#Adjusted ΔLengthZ and adjusted ΔWeightZ was ΔLengthZ and ΔWeightZ adjusted for respective associated variables by analysis of covariance(for example, ΔLengthZ of different PMA at birth subgroups(34, 35 and 36 weeks PMA at birth) was adjusted for Sex, PMA at visit and Maternal age; ΔWeightZ of different PMA at birth subgroups was adjusted for Sex, PMA at visit, Number of fetus and Intrauterine growth status), other variables were compared by T test, chi-square test, analysis of variance
*:Compared with 34 weeks PMA at birth subgroup, P < 0.05; §: compared with 35 week PMA at birth subgroup, P < 0.05; ε: compared with female subgroup, P < 0.05; κ: compared with singleton subgroup, P < 0.05; ƭ: compared with SGA subgroup, P < 0.05; ƞ: compared with AGA subgroup, P < 0.05
aAbbreviations: PMA Postmenstrual age, SGA Small-for-gestational-age, AGA appropriate-for-gestational-age, LGA Large-for-gestational-age, LengthZ Z-score of Length calculated by Fenton reference, WeightZ Z-score of weight calculated by Fenton reference, ΔLengthZ Z-score change of length, ΔWeightZ, Z-score change of weight