TABLE 1.
Characteristics of the study participants (mother-child dyads)1
| Quartile of maternal RBC Mn concentration, μg/L | |||||
|---|---|---|---|---|---|
| Characteristic | Q1 (6.9–29.0) | Q2 (29.2–37.4) | Q3 (37.6–48.4) | Q4 (48.6–109.8) | P value |
| n | 315 | 319 | 317 | 317 | |
| Maternal characteristics | |||||
| Maternal age, y | 0.36 | ||||
| <25 | 94 (29.8) | 94 (29.5) | 100 (31.5) | 118 (37.2) | |
| 25–34 | 157 (49.8) | 162 (50.8) | 152 (48.0) | 148 (46.7) | |
| ≥35 | 64 (20.3) | 63 (19.7) | 65 (20.5) | 51 (16.1) | |
| Race/ethnicity | <0.001 | ||||
| Black | 222 (70.5) | 212 (66.5) | 173 (54.6) | 163 (51.4) | |
| Nonblack | 93 (29.5) | 107 (33.5) | 144 (45.4) | 154 (48.6) | |
| Education | 0.15 | ||||
| High school and less | 192 (61.0) | 205 (64.3) | 197 (62.2) | 219 (69.1) | |
| College and beyond | 123 (39.0) | 114 (35.7) | 120 (37.8) | 98 (30.9) | |
| Smoking | <0.001 | ||||
| Never smoker | 229 (72.7) | 273 (85.6) | 277 (87.4) | 273 (86.1) | |
| Ever smoker | 86 (27.3) | 46 (14.4) | 40 (12.6) | 44 (13.9) | |
| Parity | 0.96 | ||||
| Nulliparous | 132 (41.9) | 130 (40.8) | 127 (40.1) | 127 (40.1) | |
| Multiparous | 183 (58.1) | 189 (59.2) | 190 (59.9) | 190 (59.9) | |
| Prepregnancy obesity2 | 82 (26.0) | 87 (27.3) | 80 (25.2) | 68 (21.5) | 0.36 |
| Hypertensive disorder3 | 67 (21.3) | 50 (15.7) | 43 (13.6) | 36 (11.4) | 0.004 |
| Diabetes4 | 54 (17.1) | 38 (11.9) | 36 (11.4) | 37 (11.7) | 0.10 |
| Child's characteristics | |||||
| Age (y) at BP measure | 7.8 ± 2.3 | 8.0 ± 2.6 | 8.6 ± 2.7 | 8.7 ± 3.0 | <0.001 |
| Sex | 0.92 | ||||
| Male | 156 (49.5) | 157 (49.2) | 161 (50.8) | 164 (51.7) | |
| Female | 159 (50.5) | 162 (50.8) | 156 (49.2) | 153 (48.3) | |
| Birthweight, kg | 2.77 ± 0.85 | 2.99 ± 0.84 | 3.11 ± 0.71 | 3.08 ± 0.70 | <0.001 |
| Gestational age, wk | 37.1 ± 3.9 | 37.9 ± 3.4 | 38.4 ± 2.8 | 38.3 ± 2.7 | <0.001 |
| Low birthweight5 | 100 (31.7) | 70 (21.9) | 49 (15.5) | 64 (20.2) | <0.001 |
| Preterm birth6 | 102 (32.4) | 76 (23.8) | 61 (19.2) | 68 (21.5) | <0.001 |
| Fetal growth restriction7 | 38 (12.1) | 35 (11.0) | 25 (7.9) | 26 (8.2) | 0.21 |
| Overweight/obese8 | 141 (44.8) | 139 (43.6) | 135 (42.6) | 138 (43.5) | 0.96 |
| BMI z score | 0.83 ± 1.18 | 0.72 ± 1.24 | 0.78 ± 1.21 | 0.78 ± 1.14 | 0.69 |
| Elevated BP9 | 89 (28.3) | 70 (21.9) | 69 (21.8) | 89 (28.1) | 0.08 |
1Values are presented as frequency (%) or mean ± SD, n = 1268 mother-child dyads. BP, blood pressure; Q, quartile.
2Prepregnancy obesity was defined as prepregnancy BMI ≥30 kg/m2.
3Hypertensive disorder includes chronic/gestational hypertension, preeclampsia, eclampsia, or HELLP syndrome, a complication of pregnancy characterized by hemolysis, elevated liver enzymes, and low platelet count.
4Diabetes includes preexisting diabetes and gestational diabetes.
5Low birthweight was defined as birthweight <2.5 kg.
6Preterm birth was defined as gestational age <37 wk.
7Fetal growth restriction was defined as birthweight for gestational age <10th percentile.
8Child overweight or obese was defined as BMI ≥85th percentile for age and sex.
9Elevated BP was defined as systolic or diastolic BP ≥90th percentile for age, sex, and height.