Skip to main content
. Author manuscript; available in PMC: 2023 Oct 1.
Published in final edited form as: J Pediatr. 2022 Jun 27;249:59–66.e1. doi: 10.1016/j.jpeds.2022.06.023

Table IV.

Prevalence and PRs for spina bifida cases by lesion level and fortification period

Lesion level fortification period No. of cases No. of live births Birth prevalence per 10 000 (95% CI) PR (95% CI) P value
All spina bifida cases*
 Prefortification (1992-1996) 573 1 407 707 4.07 (3.74-4.42) Referent Referent
 Postfortification, overall (1999-2016) 2020 6 408 355 3.15 (3.02-3.29) 0.77 (0.71-0.85) <.0001
 Early postfortification period (1999-2004) 669 2 136 303 3.13 (2.90-3.38) 0.77 (0.69-0.86) <.0001
 Mid postfortification period (2005-2010) 787 2 331 761 3.38 (3.14-3.62) 0.83 (0.74-0.92) .0006
 Recent postfortification period (2011-2016) 564 1 940 291 2.91 (2.67-3.16) 0.71 (0.64-0.80) <.0001
Upper lesion level cases
 Prefortification (1992-1996) 141 1 407 707 1.00 (0.84-1.18) Referent Referent
 Postfortification, overall (1999-2016) 177 6 408 355 0.28 (0.24-0.32) 0.28 (0.22-0.34) <.0001
 Early postfortification period (1999-2004) 75 2 136 303 0.35 (0.28-0.44) 0.35 (0.26-0.46) <.0001
 Mid postfortification period (2005-2010) 61 2 331 761 0.26 (0.20-0.34) 0.26 (0.19-0.35) <.0001
 Recent postfortification period (2011-2016) 41 1 940 291 0.21 (0.15-0.29) 0.21 (0.15-0.30) <.0001
Lower lesion level cases
 Prefortification (1992-1996) 400 1 407 707 2.84 (2.57-3.13) Referent Referent
 Postfortification, overall (1999-2016) 1709 6 408 355 2.67 (2.54-2.80) 0.94 (0.84-1.05) .25
 Early postfortification period (1999-2004) 564 2 136 303 2.64 (2.43-2.87) 0.93 (0.82-1.06) .26
 Mid postfortification period (2005-2010) 660 2 331 761 2.83 (2.62-3.05) 1.00 (0.88-1.13) .95
 Recent postfortification period (2011-2016) 485 1 940 291 2.50 (2.28-2.73) 0.88 (0.77-1.00) .06

P values are for pairwise testing of the PR against the referent group for each period stratification.

*

All cases include unknown lesion level.