Table 3.
Hazard ratios (HR) and 95% confidence intervals (95% CI) for the association between maternal intake of vitamin C and iron during pregnancy and the risk of islet autoimmunity and type 1 diabetes in the offspring.
| Islet Autoimmunity | Type 1 Diabetes | |||||||
|---|---|---|---|---|---|---|---|---|
| Model 1 n = 4887 (312) a | Model 2 n = 4706 (305) a | Model 1 n = 4943 (178) a | Model 2 n = 4757 (174) a | |||||
| HR b (95% CI) | p-Value | HR b (95% CI) | p-Value | HR b (95% CI) | p-Value | HR b (95% CI) | p-Value | |
| Vitamin C from diet | ||||||||
| per 1 SD increase | 0.97 (0.87, 1.09) | 0.62 | 0.98 (0.87, 1.10) | 0.73 | 1.05 (0.91, 1.21) | 0.51 | 1.07 (0.93, 1.23) | 0.37 |
| Q1 | 0.96 (0.73, 1.27) | 0.96 | 0.99 (0.75, 1.30) | 0.98 | 1.10 (0.77, 1.58) | 0.47 | 1.08 (0.75, 1.57) | 0.41 |
| Q2 and Q3 | 1 (ref) | 1 (ref) | 1 (ref) | 1 (ref) | ||||
| Q4 | 0.98 (0.75, 1.29) | 1.02 (0.77, 1.34) | 1.25 (0.88, 1.77) | 1.27 (0.89, 1.81) | ||||
| Total vitamin C intake c | ||||||||
| per 1 SD increase | 0.90 (0.79, 1.03) | 0.12 | 0.91 (0.80, 1.03) | 0.14 | 0.99 (0.86, 1.15) | 0.94 | 1.01 (0.87, 1.17) | 0.92 |
| Q1 | 0.96 (0.74, 1.26) | 0.32 | 0.98 (0.75, 1.28) | 0.36 | 0.92 (0.64, 1.32) | 0.74 | 0.88 (0.61, 1.28) | 0.73 |
| Q2 and Q3 | 1 (ref) | 1 (ref) | 1 (ref) | 1 (ref) | ||||
| Q4 | 0.80 (0.61, 1.07) | 0.82 (0.61, 1.09) | 0.87 (0.60, 1.26) | 0.89 (0.61, 1.29) | ||||
| Iron from diet | ||||||||
| per 1 SD increase | 1.09 (0.99, 1.22) | 0.09 | 1.07 (0.96, 1.19) | 0.22 | 1.10 (0.96, 1.26) | 0.17 | 1.09 (0.95, 1.25) | 0.23 |
| Q1 | 0.70 (0.52, 0.94) | 0.06 | 0.71 (0.53, 0.97) | 0.09 | 0.63 (0.42, 0.94) | 0.06 | 0.95 (0.72, 1.26) | 0.71 |
| Q2 and Q3 | 1 (ref) | 1 (ref) | 1 (ref) | 1 (ref) | ||||
| Q4 | 0.94 (0.73, 1.23) | 0.92 (0.70, 1.20) | 1.00 (0.71, 1.40) | 0.89 (0.68, 1.18) | ||||
| Total iron intake c | ||||||||
| per 1 SD increase | 0.99 (0.88, 1.11) | 0.82 | 0.98 (0.87, 1.10) | 0.71 | 0.94 (0.81, 1.10) | 0.46 | 0.92 (0.78, 1.08) | 0.30 |
| Q1 | 0.94 (0.71, 1.24) | 0.79 | 0.95 (0.72, 1.26) | 0.71 | 1.01 (0.71, 1.45) | 0.98 | 1.01 (0.70, 1.45) | 0.89 |
| Q2 and Q3 | 1 (ref) | 1 (ref) | 1 (ref) | 1 (ref) | ||||
| Q4 | 0.92 (0.70, 1.20) | 0.89 (0.68, 1.18) | 0.97 (0.68, 1.39) | 0.92 (0.64, 1.33) | ||||
Abbreviations: Q1–Q4, quarter. a n represents total number in the analyses and number in parenthesis represents numbers of children with the outcome. b HRs (95% CI) are from Cox regression analysis (p values from Wald test). c Total vitamin C and total iron intake from diet and dietary supplements. Model 1: Energy adjusted with the Willett’s residual method. Model 2: As model 1 and further adjusted for sex, family history of diabetes HLA genotype.