Table 1.
Characteristics of the Participants at Baseline in the India and Tanzania Trial Populations.*
| Characteristic | India Trial (N = 11,000) | Tanzania Trial (N = 11,000) | |||
|---|---|---|---|---|---|
| 500 mg Calcium (N = 5497) | 1500 mg Calcium (N = 5503) | 500 mg Calcium (N = 5503) | 1500 mg Calcium (N = 5497) | ||
| Maternal age — no. (%) | |||||
| 18–24 yr | 3372 (61.3) | 3436 (62.4) | 3882 (70.5) | 3879 (70.6) | |
| 25–29 yr | 1616 (29.4) | 1550 (28.2) | 1299 (23.6) | 1257 (22.9) | |
| ≥30 yr | 509 (9.3) | 517 (9.4) | 322 (5.9) | 361 (6.6) | |
| Maternal education — no./total no. (%) | |||||
| No formal education | 162/5496 (2.9) | 168/5502 (3.1) | 82/5496 (1.5) | 94/5491 (1.7) | |
| Primary education | 215/5496 (3.9) | 199/5502 (3.6) | 1802/5496 (32.8) | 1744/5491 (31.8) | |
| Secondary or higher education | 5119/5496 (93.1) | 5135/5502 (93.3) | 3612/5496 (65.7) | 3653/5491 (66.5) | |
| Wealth quintile — no./total no. (%) | |||||
| Quintile 1: Poorest | 1104/5496 (20.1) | 1096/5502 (19.9) | 1099/5503 (20.0) | 1099/5497 (20.0) | |
| Quintile 2: Second poorest | 1076/5496 (19.6) | 1130/5502 (20.5) | 1109/5503 (20.2) | 1093/5497 (19.9) | |
| Quintile 3: Middle | 1122/5496 (20.4) | 1071/5502 (19.5) | 1119/5503 (20.3) | 1081/5497 (19.7) | |
| Quintile 4: Second richest | 1077/5496 (19.6) | 1131/5502 (20.6) | 1055/5503 (19.2) | 1145/5497 (20.8) | |
| Quintile 5: Richest | 1117/5496 (20.3) | 1074/5502 (19.5) | 1121/5503 (20.4) | 1079/5497 (19.6) | |
| Gestational age — no. (%)† | |||||
| <13 wk 0 days | 1675 (30.5) | 1718 (31.2) | 1598 (29.0) | 1699 (30.9) | |
| 13 wk 0 days to 16 wk 6 days | 2231 (40.6) | 2170 (39.4) | 2085 (37.9) | 2070 (37.7) | |
| 17 wk 0 days to 20 wk 0 days | 1591 (28.9) | 1615 (29.3) | 1820 (33.1) | 1728 (31.4) | |
| Maternal height <155.0 cm — no./total no. (%) | 3241/5496 (59.0) | 3295/5502 (59.9) | 1853/5503 (33.7) | 1824/5497 (33.2) | |
| Body-mass index — no./total no. (%)‡ | |||||
| <18.5 | 898/5496 (16.3) | 886/5502 (16.1) | 452/5503 (8.2) | 440/5497 (8.0) | |
| 18.5–24.9 | 2846/5496 (51.8) | 2869/5502 (52.1) | 3202/5503 (58.2) | 3162/5497 (57.5) | |
| 25.0–29.9 | 1238/5496 (22.5) | 1225/5502 (22.3) | 1269/5503 (23.1) | 1306/5497 (23.8) | |
| ≥30.0 | 514/5496 (9.4) | 522/5502 (9.5) | 578/5503 (10.5) | 588/5497 (10.7) | |
| Hemoglobin concentration — no. (%) | |||||
| ≥11.0 g/dl | 3018 (54.9) | 3034 (55.1) | 3241 (58.9) | 3233 (58.8) | |
| 10.0–10.9 g/dl | 1762 (32.1) | 1679 (30.5) | 1534 (27.9) | 1531 (27.9) | |
| 7.0–9.9 g/dl | 687 (12.5) | 766 (13.9) | 728 (13.2) | 732 (13.3) | |
| <7.0 g/dl | 15 (0.3) | 13 (0.2) | 0 | 1 (<0.1) | |
| Living with HIV infection — no. (%) | NA | NA | 107 (1.9) | 89 (1.6) | |
| Family history of hypertension — no./total no. (%) | 326/5496 (5.9) | 325/5502 (5.9) | 1025/5503 (18.6) | 1050/5497 (19.1) | |
| High blood pressure — no. (%)§ | 34/5482 (0.6) | 45/5492 (0.8) | 14/5503 (0.3) | 18/5497 (0.3) | |
| Taking antihypertensive drug — no. (%) | 1/5496 (<0.1) | 3/5502 (0.1) | 10/5503 (0.2) | 9/5497 (0.2) | |
| Median caloric intake (IQR) — kcal¶ | 1169 (946–1421) | 1166 (956–1421) | 2862 (2144–3600) | 2882 (2206–3647) | |
| Median dietary calcium intake (IQR) — mg/day¶ | 431 (292–629) | 440 (297–633) | 413 (193–1143) | 413 (190–1233) | |
| Dietary calcium intake <800 mg/day — no./total no. (%)‖ | 4774/5497 (86.8) | 4802/5503 (87.3) | 3046/4535 (67.2) | 3035/4526 (67.1) | |
HIV denotes human immunodeficiency virus, IQR interquartile range, and NA not available.
Gestational age was defined on the basis of the reported date of the last menstrual period (enrollment criterion). In the India trial, 11 participants (6 in the 500-mg group and 5 in the 1500-mg group) underwent randomization between 20 weeks 1 day of gestation age and 20 weeks 6 days of gestational age.
The body-mass index is the weight in kilograms divided by the square of the height in meters.
High blood pressure was defined as a systolic blood pressure of at least 140 mm Hg or a diastolic blood pressure of at least 90 mm Hg.
In the Tanzania trial, data on dietary intake were missing for 968 participants in the 500-mg group and for 971 in the 1500-mg group.
An intake of 800 mg of calcium per day is the U.S. Institute of Medicine estimated average requirement for calcium intake among pregnant or lactating persons 19 to 50 years of age.