Sociodemographic characteristics of participants, including 8045 couples (parents) and 15 615 pregnant women, who were enrolled in the Shanghai Preconception Cohort
| Characteristics | Couples (parents) who completed preconception questionnaires | Additional pregnant women who completed both preconception and first-trimester questionnaires | P value* | ||||
| Men (n=8045) | Women (n=11 099) | Pregnant women (n=15 615) | |||||
| Age (years), mean±SD | 8045 | 31.4±4.5 | 11 099 | 29.9±3.9 | 15 615 | 29.9±4.0 | 0.995 |
| Ethnicity, n (%) | 8001 | 11 032 | 15 587 | 0.407 | |||
| Han nationality | 7843 (98.0) | 10 773 (97.6) | 15 245 (97.8) | ||||
| Others | 158 (2.0) | 259 (2.4) | 342 (2.2) | ||||
| Educational level, n (%) | 7996 | 10 988 | 15 553 | <0.001 | |||
| High school or less | 613 (7.7) | 947 (8.6) | 2117 (13.6) | ||||
| College or above | 7383 (92.3) | 10 041 (91.4) | 13 436 (86.4) | ||||
| Annual household income, n (%) | 7134 | 8747 | NA | – | |||
| <￥100 000 | 1555 (21.8) | 2114 (24.2) | |||||
| ≥￥100 000 | 5579 (78.2) | 6636 (75.8) | |||||
| Occupation, n (%) | 7937 | 10 909 | 15 453 | <0.001 | |||
| Entrepreneur | 190 (2.4) | 156 (1.4) | 171 (1.1) | ||||
| Farmer | 35 (0.4) | 49 (0.5) | 79 (0.5) | ||||
| Self-employed | 261 (3.3) | 329 (3.0) | 862 (5.6) | ||||
| Manager | 1712 (21.6) | 2101 (19.3) | 2650 (17.2) | ||||
| Technician | 2998 (37.7) | 2269 (20.8) | 2403 (15.6) | ||||
| Company clerk | 678 (8.5) | 857 (7.9) | 3422 (22.1) | ||||
| Others | 2063 (26.0) | 5148 (47.2) | 5866 (37.9) | ||||
| Attending preconception pregnancy examination, n (%) | NA | NA | 15 594 | – | |||
| Yes | 3374 (22.5) | ||||||
| No | 11 654 (77.5) | ||||||
| Number of pregnancies, n (%) | NA | NA | 15 028 | – | |||
| 1 | 7804 (49.9) | ||||||
| 2 | 4598 (30.4) | ||||||
| ≥3 | 3192 (19.7) | ||||||
| Miscarriage or stillbirth, n (%) | NA | NA | 15 532 | – | |||
| Yes | 4838 (31.1) | ||||||
| No | 10 694 (68.9) | ||||||
| Smoking, n (%) | 8018 | 11 064 | 15 571 | <0.001 | |||
| Yes | 2517 (31.4) | 248 (2.2) | 161 (1.0) | ||||
| No | 5501 (68.6) | 10 816 (97.8) | 15 410 (99.0) | ||||
| Alcohol drinking, n (%) | 7883 | 10 906 | 15 566 | <0.001 | |||
| Yes | 4840 (61.4) | 3374 (30.9) | 1599 (0.3) | ||||
| No | 3043 (38.6) | 7532 (69.1) | 13 976 (89.7) | ||||
| Location of home, n (%) | 8045 | 11 099 | NA | – | |||
| Urban districts | 4473 (55.6) | 4728 (42.6) | |||||
| Suburban districts | 3572 (44.4) | 6371 (57.4) | |||||
*Comparisons between preconception women and pregnant women. t-Tests were used to compare numerical variable (age). χ2 tests were used to compare categorical variables (ethnicity, educational level, occupation, smoking and alcohol drinking). Of 8045 preconception men, values were missing in ethnicity (n=44), educational level (n=49), annual household income (n=911), occupation (n=108), smoking (n=27) and alcohol drinking (n=162). Of 11 099 preconception women, values were missing in ethnicity (n=67), educational level (n=111), annual household income (n=2352), occupation (n=190), smoking (n=35) and alcohol drinking (n=193). Of 15 615 pregnant women, values were missing in ethnicity (n=28), educational level (n=62), occupation (n=162), attending preconception pregnant examination (n=21), parity (n=587), miscarriage or stillbirth (n=83), smoking (n=44) and alcohol drinking (n=49).
NA, not applicable.