Table 1.
Characteristics of women born in southeastern China between 1955 and 1985 by 5-year birth cohort
| 1955–60 | 1961–65 | 1966–70 | 1971–75 | 1976–80 | 1981–85 | Association | Trend | |
|---|---|---|---|---|---|---|---|---|
| (n = 7 128) | (n = 53 245) | (n = 309 379) | (n = 369 971) | (n = 348 356) | (n = 79 040) | P Value | P Value | |
| Age at menarche (yrs), mean (SD) | 15.7 (1.5) | 15.5 (1.39) | 15.1 (1.3) | 14.9 (1.3) | 14.8 (1.2) | 14.7 (1.2) | <0.0001* | <0.0001† |
| Age at registration (yrs), mean (SD) | 36.2 (2.6) | 32.3 (2.25) | 27.3 (3.3) | 25.1 (2.6) | 24.4 (2.0) | 22.3 (1.1) | <0.0001* | <0.0001† |
| Region, n (%) | <0.0001‡ | <0.0001¶ | ||||||
| Urban | 847 (11.9) | 3 902 (7.3) | 39 698 (12.8) | 51 565 (13.9) | 58 740 (16.9) | 9 127 (11.6) | ||
| Rural | 6 281 (88.1) | 49 343 (92.7) | 269 681 (87.2) | 318 406 (86.1) | 289 616 (83.1) | 69 913 (88.5) | ||
| Education, n (%) | <0.0001‡ | <0.0001§ | ||||||
| High school or above | 876 (12.3) | 6 195 (11.67) | 52 373 (17.0) | 78 738 (21.3) | 124 960 (35.9) | 25 420 (32.3) | ||
| Middle school | 2 151 (30.3) | 25 278 (47.60) | 167 684 (54.4) | 232 677 (63.0) | 200 758 (57.7) | 49 501 (62.8) | ||
| Primary school or less | 4 076 (57.4) | 21 634 (40.5) | 88 225 (28.6) | 57 768 (15.7) | 22 152 (6.4) | 3 897 (4.9) | ||
| Medical health history, n (%) | <0.0001‡ | <0.0001¶ | ||||||
| No chronic diseases | 6 854 (96.2) | 51 096 (96.0) | 298 418 (96.5) | 360 774 (97.5) | 343 415 (98.6) | 78 453 (99.3) | ||
| At least one chronic disease | 274 (3.8) | 2 149 (4.0) | 10 961 (3.5) | 9 197 (2.5) | 4 941 (1.4) | 587 (0.7) |
Missing age at registration, 20; Missing education information, 2 756.
*P value from ANOVA.
†P value from linear regression.
‡P value from Pearson Chi-square test.
¶P value from Cochrane-Armitage Trend test.
§P value from Mantel-Haenszel test.