Table 1. Prevalence of neural tube defects before and after the mandatory fortification of flours with folic acid, Brazil, 2001–2014.
| Type | No. of births investigated | No. of births with NTD | Prevalence |
||
|---|---|---|---|---|---|
| NTD per 1000 births | Ratio (95% CI) |
Change, % | |||
| Live births | |||||
| Pre-fortificationa | 4 938 343 | 2 823 | 0.57 | 1.29 (1.24–1.35) | −22.8 |
| Post-fortificationb | 12 987 386 | 5 731 | 0.44 | 1 | |
| Total | 17 925 729 | 8 554 | – | – | – |
| Stillbirths | |||||
| Pre-fortificationa | 65 121 | 1 155 | 17.74 | 1.52 (1.40–1.63) | −34.0 |
| Post-fortificationb | 129 737 | 1 518 | 11.70 | 1 | |
| Total | 194 858 | 2 673 | – | – | – |
| All births | |||||
| Pre-fortificationa | 5 003 464 | 3 978 | 0.79 | 1.43 (1.38–1.50) | −30.1 |
| Post-fortificationb | 13 117 123 | 7 249 | 0.55 | 1 | |
| Total | 18 120 587 | 11 227 | – | – | – |
CI: confidence interval; NTD: neural tube defect.
a The pre-fortification study period ran from 1 January 2001 to 31 December 2004 – although fortification became mandatory in June 2014.
b The post-fortification study period, which ran from 1 January 2005 to 31 December 2014, was used as the reference category in the calculation of prevalence ratios.