Table 1.
Characteristics of the study sample by the prevalence of neural tube defects, before (2002–2004) and after (2011–2012) a massive folic acid supplementation programme, Shanxi Province and Jiangsu Province, China
| High-prevalence population | Low-prevalence population | |||||||
|---|---|---|---|---|---|---|---|---|
| Before (n 562) | After (n 1047) | Before (n 695) | After (n 689) | |||||
| Variable | n | % | n | % | n | % | n | % |
| Age (years) | ||||||||
| <25 | 113 | 23·4 | 261 | 25·0* | 257 | 48·0 | 255 | 37·0*† |
| 25–29 | 198 | 41·1 | 548 | 52·4 | 247 | 46·2 | 341 | 49·5 |
| ≥30 | 171 | 35·5 | 237 | 22·7 | 31 | 5·8 | 93 | 13·5 |
| Gestational weeks | ||||||||
| <12 | 517 | 92·0 | 227 | 21·7* | 556 | 80·0 | 562 | 81·6*† |
| ≥12 | 45 | 8·0 | 820 | 78·3 | 139 | 20·0 | 127 | 18·4 |
| BMI (kg/m2) | ||||||||
| <25 | 488 | 87·0 | 802 | 76·6* | 649 | 96·4 | 625 | 91·9*† |
| ≥25 | 73 | 13·0 | 245 | 23·4 | 24 | 3·6 | 55 | 8·1 |
| Education (%) | ||||||||
| Middle school or less | 298 | 53·1 | 262 | 25·0* | 118 | 17·0 | 70 | 10·2*† |
| High school or more | 263 | 46·9 | 785 | 75·0 | 576 | 83·0 | 619 | 89·8 |
| Residence | ||||||||
| Urban | 204 | 36·3 | 695 | 66·4* | 368 | 52·9 | 436 | 63·3* |
| Rural | 358 | 63·7 | 352 | 33·6 | 327 | 47·1 | 253 | 36·7 |
| Gravidity | ||||||||
| Primigravidas | 175 | 31·1 | 588 | 56·2* | 406 | 58·8 | 393 | 57·0 |
| Multigravidas | 387 | 68·9 | 458 | 43·8 | 285 | 41·2 | 296 | 43·0 |
Note: Some variables have missing data.
*P<0·05 before and after the programme in the same population.
†P<0·05 between the high- and low-prevalence groups after the programme.