Table 7.
Baseline characteristics, iodine intake, urine iodine concentration (UIC), urine iodine creatinine ratio (UICR) and iodine-related variables according to iodine supplement use during dietary record.
| Iodine Supplement Use during Dietary Record | p | ||
|---|---|---|---|
| Yes (n = 63) | No (n = 40) | ||
| Median (p25, p75) | Median (p25, p75) | ||
| Characteristics (continuous variables) | |||
| Age mother (years) | 34.91 (33.01, 38.45) | 36.31 (32.56, 39.39) | 0.570 |
| Breastfeeding duration (month) | 6.44 (4.40, 9.33) | 9.46 (5.08, 17.01) | 0.007 |
| Pre-pregnancy BMI (km/m2) | 21.96 (20.30, 24.91) | 22.25 (20.36, 24.57) | 0.789 |
| Current BMI (km/m2) | 23.07 (21.13, 25.29) | 22.66 (20.66, 24.73) | 0.725 |
| Gestational age (weeks) | 39 (37, 40) | 39 (38, 40) | 0.580 |
| Birth weight (g) | 3160.00 (2785.00, 3400.00) | 3370.00 (2812.50, 3525.00) | 0.203 |
| Iodine Intake (µg/day) | |||
| From food alone | 103.60 (83.60, 132.25) | 104.64 (83.02, 115.42) | 0.365 |
| Total intake a | 329.20 (278.15, 378.90) | 143.30 (187.51, 91.74) | <0.000 |
| UIC (µg/L) | 119.05 (70.24, 160.50) | 110.74 (87.97, 159.19) | 0.995 |
| UICR (µg iodine/mg creatinine) b | 0.116 (0.072, 0.153) | 0.084 (0.061, 0.145) | 0.109 |
| n (%) | n (%) | p | |
| Characteristics (categorical variables) | |||
| Breastfeeding duration | |||
| 1–5 months | 29 (46.03) | 15 (37.50) | 0.011 |
| 6–12 months | 25 (39.68) | 9 (22.50) | |
| >12 months | 9 (14.29) | 16 (40.00) | |
| Pre-pregnancy BMI categories | |||
| <25 | 49 (77.78) | 32 (80.00) | 1.000 |
| 25–29.9 | 7 (11.11) | 4 (10.00) | |
| ≥30 | 7 (11.11) | 4 (10.00) | |
| Current BMI categories | |||
| <25 | 46 (73.02) | 32 (80.00) | 0.620 |
| 25–29.9 | 9 (14.29) | 3 (7.50) | |
| ≥30 | 8 (12.70) | 5 (12.50) | |
| Breast feeding c | |||
| Exclusive | 32 (51.61) | 14 (35.00) | 0.109 |
| Partial d | 30 (48.39) | 26 (65.00) | |
| Hypothyroidism in pregnancy | |||
| Yes | 52 (82.54) | 35 (87.50) | 0.585 |
| No | 11 (17.46) | 5(12.50) | |
| Tandem breastfeeding | |||
| Yes | 2 (3.17) | 0 (0.00) | 0.520 |
| No | 61 (96.83) | 40 (100.00) | |
| Education level | |||
| Secondary school or technical studies | 10 (15.87) | 4 (10.00) | 0.558 |
| University | 53 (84.13) | 36 (90.00) | |
| Sex | |||
| Girl | 27 (42.86) | 26 (65.00) | 0.043 |
| Boy | 36 (57.14) | 14 (35.00) | |
| Children | |||
| 1 | 36 (57.14) | 22(55.00) | 0.841 |
| >1 | 27 (42.86) | 18 (42.86) | |
| BMIC ≥ 200 mcg/L | |||
| Yes | 29 (46.03) | 3 (7.50) | <0.000 |
| No | 34 (53.97) | 37 (92.50) | |
| Iodine-related variables | |||
| Iodine supplement use during pregnancy | |||
| Yes | 56 (88.89) | 31 (77.50) | 0.313 |
| Partial | 5 (7.94) | 6 (15.00) | |
| No | 2 (3.17) | 3 (7.50) | |
| Use of iodized salt during dietary record | |||
| Yes | 43 (68.25) | 23 (57.50) | 0.120 |
| No | 7 (11.11) | 11 (27.50) | |
| Missing data | 13 (20.63) | 6 (15.00) | |
| Consumption of dairy products per day | |||
| ≥3 portion | 26 (41.27) | 10 (25.00) | 0.137 |
| <3 portion | 37 (58.73) | 30 (75.00) | |
| Consumption of fish per week | |||
| ≥2 portion | 35 (55.56) | 21 (52.50) | 0.840 |
| <2 portion | 28 (44.44) | 19 (47.50) | |
a Sample size regarding total iodine intake (considering information from diet, iodized salt and iodine supplement intake) was n = 84 (missing data for 19 additionally donors as the type of salt consumed during the dietary record was not reported), b n = 112 (due to 1 missing data), c n = 112 (due to one stillbirth), d Complementary food introduction. BMIC: breast milk iodine concentration.