Table 3. Associations Between Vitamin D Supplementation (1200 IU vs 400 IU) and Developmental Milestonesa.
| Developmental milestone score | Mean (SD) | MD or OR (95% CI) | P value | |
|---|---|---|---|---|
| 400-IU group (n = 322-336) | 1200-IU group (n = 311-323) | |||
| At 12-mo follow-up | ||||
| ASQ total score | ||||
| Model 1 | 45.3 (7.3) | 46.1 (7.9) | MD, 0.77 (−0.39 to 1.93) | .20 |
| Model 2 | 45.0 (7.1) | 46.2 (7.9) | MD, 1.17 (−0.06 to 2.38) | .06 |
| ASQ total score ≤ −1 SD, No. (%) | ||||
| Model 1 | 45 (13.4) | 53 (16.5) | OR, 1.27 (0.83 to 1.96) | .27 |
| Model 2 | 38 (13.6) | 46 (16.7) | OR, 1.37 (0.85 to 2.20) | .20 |
| At 24-mo follow-up | ||||
| ASQ total score | ||||
| Model 1 | 51.0 (5.2) | 51.3 (5.5) | MD, 0.34 (−0.51 to 1.18) | .43 |
| Model 2 | 50.9 (5.3) | 51.5 (5.5) | MD, 0.48 (−0.40 to 1.36) | .29 |
| ASQ total score ≤ −1 SD, No. (%) | ||||
| Model 1 | 44 (13.6) | 49 (15.8) | OR, 1.19 (0.76 to 1.84) | .45 |
| Model 2 | 39 (14.3) | 40 (14.9) | OR, 1.18 (0.71 to 1.95) | .53 |
Abbreviations: ASQ, Ages and Stages Questionnaire; MD, mean difference; OR, odds ratio.
The MDs and 95% CIs from Tobit regression analyses refer to differences in ASQ total raw scores of 1200-IU group vs 400-IU group. OR and 95% CIs from logistic regression analyses show the odds of belonging to the group scoring –1 SD or less vs more than –1 SD in ASQ for 1200-IU group vs 400-IU group. All Cohen d effect sizes less than 0.11 in continuous variables. Model 1 is the crude model. Model 2 is adjusted for sex, length of gestation, duration of breastfeeding, age at follow-up, maternal age at delivery, maternal smoking and depressive symptoms at childbirth, and maternal educational level (missing values were dummy-coded to their own category). In model 2, 555 children were available at 12-month follow-up and 542 children were available at 24-month follow-up.