Table 2.
Associations of demographic and clinical characteristics of typically developing children (n = 234) and their mothers with categorical and continuous dried blood spot 25-hydroxyvitamin D
| Categorical | Continuous | |||||
|---|---|---|---|---|---|---|
| Variable | Deficient (<50 nmol/L) (n = 49) |
Insufficient (50-<75 nmol/L) (n = 62) |
Sufficient (≥75 nmol/L) (n = 123) |
P-value | Estimate (SE) | P-value |
| Child Sex, n (%) | 0.35 | |||||
| Female | 7 (14.3%) | 11 (17.7%) | 25 (20.3%) | reference | – | |
| Male | 42 (85.7%) | 51 (82.3%) | 98 (79.7%) | −10.79 (6.34) | 0.09 | |
| Child Race-Ethnicity, n (%) | < 0.001 | |||||
| White Non-Hispanic | 18 (36.7%) | 26 (41.9%) | 81 (65.9%) | reference | – | |
| Hispanic | 14 (28.6%) | 25 (40.3%) | 24 (19.5%) | −18.21 (5.60) | 0.011 | |
| Other | 17 (34.7%) | 11 (17.7%) | 18 (14.6%) | −21.88 (6.25) | < 0.001 | |
| Child Age at DBS Collection (hours)1, mean (SD) | 35.1 (23.3) | 35.3 (19.9) | 39.5 (36.0) | 0.49 | 0.14 (0.08) | 0.11 |
| Child Age at Diagnosis (months), mean (SD) | 43.5 (9.9) | 42.0 (8.8) | 42.0 (10.4) | 0.43 | −0.27 (0.25) | 0.28 |
| Child Birth Year, n (%) | 0.42 | |||||
| 1998–2001 | 4 (8.2%) | 11 (17.7%) | 23 (18.7%) | 7.80 (7.65) | 0.31 | |
| 2002 | 11 (22.4%) | 17 (27.4%) | 29 (23.6%) | 1.85 (6.78) | 0.79 | |
| 2003 | 23 (46.9%) | 12 (19.4%) | 33 (26.8%) | reference | – | |
| 2004 | 6 (12.2%) | 19 (30.6%) | 30 (24.4%) | 8.83 (6.85) | 0.20 | |
| 2005–2006 | 5 (10.2%) | 3 (4.8%) | 8 (6.5%) | −2.51 (10.49) | 0.81 | |
| Child Birth Season, n (%) | 0.56 | |||||
| Spring (Mar, Apr, May) | 17 (34.7%) | 18 (29.0%) | 23 (18.7%) | −12.85 (6.88) | 0.06 | |
| Summer (Jun, Jul, Aug) | 7 (14.3%) | 11 (17.7%) | 43 (35.0%) | 13.65 (6.79) | 0.04 | |
| Fall (Sep, Oct, Nov) | 10 (20.4%) | 13 (21.0%) | 33 (26.8%) | reference | – | |
| Winter (Dec, Jan, Feb) | 15 (30.6%) | 20 (32.3%) | 24 (19.5%) | −10.42 (6.85) | 0.13 | |
| Gestation Age (weeks)2, mean (SD) | 39.6 (1.3) | 39.7 (1.3) | 38.8 (2.1) | 0.04 | −3.85 (1.33) | 0.004 |
| Maternal age (years), mean (SD) | 31.0 (5.8) | 29.4 (5.2) | 31.1 (5.8) | 0.50 | 0.49 (0.43) | 0.26 |
| Maternal age group, n (%) | 0.34 | |||||
| <25 | 10 (20.4%) | 11 (17.7%) | 20 (16.3%) | −8.00 (6.92) | 0.25 | |
| 25 to <30 | 6 (12.2%) | 20 (32.3%) | 21 (17.1%) | −1.93 (6.59) | 0.77 | |
| 30 to 35 | 25 (51.0%) | 25 (40.3%) | 56 (45.5%) | reference | – | |
| 35+ | 8 (16.3%) | 6 (9.7%) | 26 (21.1%) | 4.26 (6.98) | 0.54 | |
| Maternal Education, n (%) | 0.17 | |||||
| Bachelor degree or more | 27 (55.1%) | 30 (48.4%) | 70 (56.9%) | reference | – | |
| Some College/Vocational Degree | 12 (24.5%) | 17 (27.4%) | 41 (33.3%) | 0.24 (5.55) | 0.97 | |
| High school or less | 10 (20.4%) | 15 (24.2%) | 12 (9.8%) | −16.09 (6.96) | 0.02 | |
| Maternal Pre-Pregnancy BMI (kg/m2)3, mean (SD) | 25.8 (5.0) | 25.8 (5.1) | 24.1 (3.7) | 0.03 | −1.24 (0.55) | 0.02 |
| Maternal Pre-Pregnancy BMI3, n (%) | 0.001 | |||||
| Underweight | 1 (2.1%) | 1 (1.6%) | 4 (3.3%) | reference | – | |
| Normal | 21 (44.7%) | 31 (50.8%) | 75 (61.5%) | −15.05 (15.46) | 0.33 | |
| Overweight | 16 (34.0%) | 19 (31.1%) | 33 (27.0%) | −21.42 (15.76) | 0.17 | |
| Obese | 9 (19.1%) | 10 (16.4%) | 10 (8.2%) | −30.02 (16.59) | 0.07 | |
| Periconceptional Prenatal Vitamin Use?4, n (%) | ||||||
| Yes | 29 (64.4%) | 29 (48.3%) | 81 (67.5%) | 0.33 | 6.67 (5.09) | 0.19 |
| No | 16 (35.6%) | 31 (51.7%) | 39 (32.5%) | reference | – | |
| Folic Acid Intake (μg)5, mean (SD) | 521 (406) | 524 (485) | 629 (392) | 0.06 | 0.01 (0.006) | 0.06 |
| Paternal age (years), mean (SD) | 34.0 (6.6) | 31.2 (6.2) | 33.2 (6.9) | 0.93 | 0.24 (0.37) | 0.52 |
| Home Ownership6, n (%) | ||||||
| Own Home | 33 (73.3%) | 50 (80.6%) | 99 (81.8%) | 0.26 | 12.17 (6.06) | 0.04 |
| Do Not Own Home | 12 (26.7%) | 12 (19.4%) | 22 (18.2%) | reference | – | |
Abbreviations: DBS, Dried blood spot; BMI, body mass index; SD, standard deviation; SE, standard error. Associations with categorical dried blood spot 25-hydroxyvitamin D were assessed using Mantel-Haenszel Chi-Square test for categorical variables and Spearman correlation for continuous variables. Associations with continuous dried blood spot 25-hydroxyvitamin D were assessed using robust regression.
Missing for 3 children in the Deficient group, 6 in Insufficient, 10 in Sufficient.
Missing for 2 children in the Deficient group and 1 in Sufficient.
Missing for 2 children in the Deficient group, 1 in Insufficient, and 1 in Sufficient.
In first pregnancy month or 3 months before; missing for 4 children in the Deficient group, 2 in Insufficient, and 3 in Sufficient.
In first pregnancy month; missing for 12 children in the Deficient group, 8 in Insufficient, and 17 in Sufficient.
Missing for 4 children in the Deficient group, 2 in Sufficient.