[1] "infant"
[1] "infant"
id:  1111 
gender: male 
Data:
  age.mon ht.cm wt.kg
1       0 49.99  3.53
2       3 62.08  6.39
3       6 67.86  8.16
4      12 76.11 10.46
5      18 82.41 11.80
6      24 87.66 12.74
7      30 92.13 13.56
8      36 95.45 14.33
id:  2222 
gender: female 
Data:
  age.mon ht.cm wt.kg
1       0 49.29  3.40
2       3 60.46  5.86
3       6 66.12  7.45
4      12 74.40  9.67
5      18 80.80 11.09
6      24 86.20 12.13
7      30 91.13 13.04
8      36 94.43 13.87