The sample sizes of sex-age and urban-suburban subgroups in 2005 and 2015 are shown in Table 1.
Figure 1 displays the regional trends in weight and length/height in boys and girls of urban and suburban Nanjing in 1995, 2005 and 2015. The values of weights and heights of boys aged 6 to 7 years or girls in all subgroups in 2015 was higher than those of their counterparts in 2005 and 1995. In addition, 6- to 7-year-old boys and girls in urban areas were taller and heavier than suburban children. Both suburban boys and girls had growth curves of weight and length/height in 2015 that were very close to those of urban groups, reflecting that the differences in physical growth between urban and suburban children is becoming increasingly smaller. The details of mean values for body weight and length/height in boys and girls are shown in supplementary Tables 1–4.
Table 1
The sample sizes of the surveys (2005 and 2015)
Age
|
2005
|
|
2015
|
urban
|
sub-urban
|
|
urban
|
sub-urban
|
Boys
|
Girls
|
Boys
|
Girls
|
|
Boys
|
Girls
|
Boys
|
Girls
|
Birth
|
166
|
169
|
168
|
177
|
|
207
|
191
|
-
|
-
|
1mཞ
|
197
|
187
|
134
|
135
|
|
218
|
219
|
213
|
182
|
2mཞ
|
177
|
182
|
101
|
97
|
|
212
|
190
|
152
|
129
|
3mཞ
|
184
|
195
|
142
|
135
|
|
215
|
212
|
211
|
209
|
4mཞ
|
196
|
189
|
153
|
147
|
|
208
|
204
|
109
|
103
|
5mཞ
|
190
|
188
|
139
|
124
|
|
189
|
210
|
176
|
149
|
6mཞ
|
214
|
194
|
158
|
176
|
|
218
|
210
|
214
|
209
|
8mཞ
|
207
|
205
|
154
|
151
|
|
211
|
211
|
210
|
213
|
10mཞ
|
194
|
186
|
154
|
126
|
|
211
|
218
|
215
|
211
|
12mཞ
|
204
|
200
|
165
|
150
|
|
204
|
210
|
209
|
209
|
15mཞ
|
190
|
194
|
181
|
166
|
|
207
|
215
|
187
|
185
|
18mཞ
|
188
|
188
|
185
|
162
|
|
210
|
211
|
210
|
200
|
21mཞ
|
187
|
181
|
145
|
149
|
|
208
|
188
|
206
|
169
|
2.0yཞ
|
185
|
191
|
201
|
204
|
|
199
|
189
|
216
|
209
|
2.5yཞ
|
183
|
179
|
232
|
241
|
|
191
|
200
|
211
|
224
|
3.0yཞ
|
200
|
200
|
184
|
179
|
|
211
|
223
|
213
|
214
|
3.5yཞ
|
189
|
198
|
246
|
205
|
|
208
|
221
|
221
|
214
|
4.0yཞ
|
207
|
203
|
150
|
165
|
|
211
|
212
|
208
|
210
|
4.5yཞ
|
194
|
203
|
228
|
173
|
|
210
|
204
|
217
|
204
|
5.0yཞ
|
201
|
198
|
173
|
161
|
|
221
|
210
|
212
|
211
|
5.5yཞ
|
197
|
200
|
202
|
167
|
|
203
|
228
|
207
|
209
|
6.0ཞ7y
|
206
|
236
|
243
|
245
|
|
213
|
203
|
215
|
210
|
As Figs. 2 and 3 illustrate, an increase in weight and length/height was observed during the two decades from 1995 to 2015, especially the first decade from 1995 to 2005. Figure 2A and 2B show that the increases in boys’ weight and length/height both in urban and suburban areas in the first decade were obviously positive. However, from 2005 to 2015, the increases in urban boys’ indexes in some age groups before 2.5 years old were negative. In addition, the growth of urban boys’ weight and length/height in the second decade was significantly smaller than that of the first decade. In contrast, the suburban boys’ weight and length/height in most ages from 2005 to 2015 maintained the momentum of rapid growth, especially weight (Fig. 2C-D). Figure 3 shows the relative increases in weight and length/height among urban and suburban girls, and regional trends and urban and suburban differences were similar to those of the boys. It is worth noting that the relative increases in suburban girls’ weight after 4 years old were obviously larger in the second decade.
Table 2
Information of some demographic, socioeconomic, and health funds in Nan Jing from 1995 to 2015
Characteristics
|
1995
|
2005
|
2015
|
Total population (million)
|
5.22
|
5.96
|
6.53
|
Birth rate (‰)
|
8.56
|
7.69
|
10.35
|
Natural increase rate (‰)
|
2.62
|
2.34
|
4.14
|
GDP (billion Yuan)
|
58.46
|
245.12
|
972.08
|
Proportion in three industrial sectors (%)
|
|
|
|
Agriculture
|
7.6
|
3.3
|
2.4
|
Industry
|
52.1
|
49.8
|
40.3
|
Services
|
40.3
|
46.9
|
57.3
|
GDP per captia (Yuan)
|
10887
|
40887
|
118171
|
Consumption per captia (Yuan)
|
4524
|
9593
|
43926
|
Health funds (billion Yuan)
|
-
|
0.998
|
7.254
|
Proportion of health funds (%)
|
-
|
3.16
|
6.94
|
Figure 4 displays the differences in weight and length/height between urban and suburban children in 1995, 2005 and 2015. During 1995–2005, the differences in weight and length/height were stable and sustained at high levels. For weight, the urban-suburban difference in boys and girls increased with age in all 3-year time periods, especially from 1995 and 2005 (Fig. 4A-B). After 3 years old, boys and girls had difference values in 2005 that were still larger than those in 1995, and the girls’ weight differences increased in 2005 more than those of the boys. However, in 2015, the difference between urban-suburban children sharply decreased, especially in girls. A negative difference in most age groups before 3 years old existed, indicating that the weight of suburban children was higher than that of urban children.
For length/height, the differences between urban-suburban children decreased across time, especially from 2005 to 2015 (Fig. 4C-D). Similarly, negative differences in both boys and girls before 3 years old were observed in most age groups, suggesting that the height of suburban children was taller than that of urban children before 3 years old. Notably, in 6- to 7-year-olds, the mean height difference was smaller at 0.3 cm for boys and 0.1 cm for girls in 2015, reflecting that the height of suburban boys and girls had nearly caught up to that of their urban peers by the age of 7 years.
The details about the mean values of head circumference in boys and girls in urban and suburban Nanjing in 1995, 2005 and 2015 are shown in Supplementary Tables 5 and 6. Figure 5 presents the regional changes in head circumference for urban and suburban children. As the growth curve for mean head circumference shows, head circumference generally increased during the period 1995–2005 but decreased during 2005–2015. The same situation was observed in both boys and girls of urban and suburban areas. For example, the mean head circumferences of urban boys aged 2.5 to 3 years were 49.0 cm, 49.5 cm and 49.1 cm, respectively, in 1995, 2005 and 2015. The head circumferences were 48.1 cm, 48.6 cm and 48.2 cm for urban girls aged 2.5 to 3 years. Furthermore, we found that the increases in head circumference in different sex and area subgroups from 1995 to 2005 were almost positive in different age groups but visibly negative from 2005 to 2015.