Table 1.
Characteristics of pregnant women and blood folate concentrations (nmol L−1) in a province with high prevalence of neural tube defects in northern China, 2014
| Variable | N | % | Plasma folate | RBC folate |
|---|---|---|---|---|
| Age (years) | ||||
| <25 | 266 | 24.0 | 25.9 (16.3, 40.6) | 1,022.0 (651.3, 1,370.6) |
| 25–29 | 573 | 51.8 | 28.4 (17.7, 46.3) | 993.9 (658.7, 1,403.8) |
| ≥30 | 260 | 23.5 | 32.9 (18.4, 47.1) | 1,001.3 (658.4, 1,503.6) |
| Missing | 8 | 0.7 | ||
| P | 0.019 | 0.605 | ||
| Gestational weeks | ||||
| <12 | 67 | 6.1 | 42.1 (21.2, 55.9) | 904.6 (501.3, 1,214.3) |
| 13–20 | 967 | 87.4 | 28.5 (17.9, 44.5) | 1,017.4 (691.3, 1,417.0) |
| ≥21 | 68 | 6.1 | 19.3 (8.5, 30.9) | 852.4 (433.7, 1,352.1) |
| Missing | 5 | 0.5 | ||
| P | 0.001 | 0.013 | ||
| BMI (kg m−2) | ||||
| <25 | 870 | 78.6 | 28.4 (17.5, 46.1) | 1,007.4 (666.3, 1,410.1) |
| ≥25 | 236 | 21.3 | 28.2 (18.1, 42.5) | 977.9 (651.0, 1,380.5) |
| Missing | 1 | 0.1 | ||
| P | 0.250 | 0.237 | ||
| Education (%) | ||||
| Junior high school or less | 268 | 24.2 | 27.9 (15.3, 44.6) | 939.3 (617.1, 1,356.4) |
| Senior high school | 261 | 23.6 | 26.2 (17.3, 40.7) | 1,012.2 (688.3, 1,394.2) |
| College and above | 578 | 52.2 | 29.7 (18.9, 47.3) | 1,029.7 (686.0, 1,446.1) |
| P | 0.148 | 0.235 | ||
| Occupation (%) | ||||
| Blue collar | 138 | 12.5 | 27.3 (16.7,46.9) | 1,042.9 (695.7, 1,412.4) |
| White collar | 351 | 31.7 | 29.1 (18.3, 48.1) | 973.8 (645.8, 1,418.9) |
| Others | 617 | 55.7 | 28.0 (17.4, 44.3) | 998.9 (658.7, 998.9) |
| Missing | 1 | 0.1 | ||
| P | 0.392 | 0.557 | ||
| Residence | ||||
| Urban | 569 | 51.4 | 29.5 (18.6, 48.7) | 1,003.4 (657.1, 1,419.6) |
| Rural | 538 | 48.6 | 27.3 (16.3, 42.4) | 994.3 (660.3, 1,393.4) |
| P | 0.006 | 0.691 | ||
| Gravidity | ||||
| Primigravidas | 647 | 58.4 | 27.3 (17.2, 43.5) | 992.3 (652.2, 1,394.2) |
| Multigravidas | 460 | 41.6 | 30.6 (18.2, 47.4) | 1,001.9 (670.6, 1,446.4) |
| P | 0.061 | 0.170 | ||
| Folic acid supplementation | ||||
| Yes | 1,002 | 90.5 | 29.3 (18.5, 45.8) | 1,017.4 (673.7, 1,413.1) |
| No | 104 | 9.4 | 18.4 (11.6, 37.9) | 844.3 (518.5, 1,270.4) |
| Missing | 1 | 0.1 | ||
| P | 0.016 | 0.018 | ||
Abbreviation: RBC, red blood cell.