TABLE 1.
Characteristics of all trials eligible for inclusion in the review1
| Reference | Country | Design | Total n randomized | Maternal or infant supplementation | Form of vitamin D | Dose (IU) | Supplementation timing | Additional vitamin D and/or micronutrient supplementation2 |
|---|---|---|---|---|---|---|---|---|
| Maternal vs. infant supplementation | ||||||||
| Ala-Houhala (38) | Finland | RCT | 32 | Maternal | D-23 | 1000/d | From delivery to 20 wk | |
| 29 | Infant | N/S | 1000/d | |||||
| 31 | Infant | N/S | 400/d | |||||
| 8 | Maternal and infant | No intervention | From delivery to 8 wk | |||||
| Ala-Houhala et al. (39) | Finland | Nonrandomized prospective intervention | 17 | Maternal | D-3 | 2000/d | From delivery to 15 wk | |
| 16 | Maternal | D-3 | 1000/d | |||||
| 16 | Infant | D-2 | 400/d | |||||
| Buğrul et al. (40) | Turkey | Nonrandomized prospective intervention | 50 | Maternal | D-3 | 400/d | Within 1 mo of delivery to 6 mo | All infants received 400 IU/d vitamin D-3. |
| 50 | Maternal | No intervention | ||||||
| Chan et al. (41) | United States | Nonrandomized prospective intervention | 29 | Infant | N/S | 400/d | From 2 wk to 12 mo | All lactating mothers consumed a daily multivitamin supplement containing 400 IU vitamin D and 250 mg calcium. |
| 22 | Infant | No supplementation | ||||||
| 40 | Infant | N/S | 400/L of formula (Similac) | |||||
| Chandy et al.4 (33) | India | RCT | 74 | Maternal | D-3 | 120,000/mo | Within 7 d of delivery to 9 mo | Mothers received 500 mg/d calcium. |
| 78 | Infant | D-3 | 400/d | |||||
| 78 | Maternal and infant | Placebo | ||||||
| Czech-Kowalska et al. (42) | Poland | Double-blind RCT | 86 | Maternal | D-3 | 800/d + 400/d from multivitamin | From delivery to 6 mo | Maternal multivitamin contained 200 mg/d calcium and all infants received 400 IU/d vitamin D-3. |
| 88 | Maternal | D-3 | 0 + 400/d from multivitamin | |||||
| Hollis and Wagner (43) | United States | RCT | 9 | Maternal | D-2 | 3600/d | From 1 mo of delivery to 4 mo | All mothers received a multivitamin containing 400 IU/d vitamin D-3. |
| 9 | Maternal | D-2 | 1600/d | |||||
| Hollis et al.4 (34) | United States | Double-blind RCT | 165 | Maternal | D-3 | 6000/d + 400/d from prenatal vitamin | Within 4–6 wk of delivery to 7 mo | Infants received a liquid drop containing placebo. |
| 55 | Maternal | D-3 | 2000/d + 400/d from prenatal vitamin | |||||
| 169 | Maternal | D-3 | 0 + 400/d from prenatal vitamin | Within 4–6 wk of delivery to 7 mo | Infants received a liquid supplement containing 400 IU/d vitamin D-3. | |||
| March et al. (44) | Canada | Double-blind RCT | 74 | Maternal | D-3 | 2000/d | From 13–24 weeks of gestation to 8 wk postpartum | Intervention dose provided in the form of a multivitamin. |
| 76 | Maternal | D-3 | 1000/d | |||||
| 76 | Maternal | D-3 | 400/d | |||||
| Naik et al. (45) | India | Double-blind RCT | 65 | Maternal | D-3 | 600,000 | Provided as 60,000 IU/d from delivery to 10 d | All mothers received 500 mg/d calcium and 125 IU/d vitamin D-3 postnatally. |
| 65 | Maternal | Placebo | From delivery to 10 d | |||||
| Niramitmahapanya et al. (46) | Thailand | Double-blind RCT | 35 | Maternal | D-3 | 1800/d | From delivery to 6 wk | |
| 33 | Maternal | Placebo | ||||||
| Oberhelman et al. (47) | United States | RCT | 20 | Maternal | D-3 | 150,000 | Single dose at delivery | |
| 20 | Maternal | D-3 | 5000/d | From delivery to day 28 | ||||
| Roth et al. (48) | Bangladesh | Double-blind RCT | 260 | Maternal | D-3 | 28,000/wk prenatal and postpartum | From 17–24 weeks of gestation to 6 mo postpartum | All mothers received daily 500 mg calcium, 66 mg iron, and 350 µg folic acid throughout gestation. |
| 260 | Maternal | D-3 | 28,000/wk prenatal, 0/wk postpartum | |||||
| 260 | Maternal | D-3 | 16,800/wk prenatal, 0/wk postpartum | |||||
| 260 | Maternal | D-3 | 4200/wk prenatal, 0/wk postpartum | |||||
| 260 | Maternal | D-3 | Placebo prenatal and postpartum | |||||
| Rothberg et al.4 (35) | South Africa | Double-blind RCT | 20 | Maternal | N/S | 1000/d | From delivery to 6 wk | |
| 20 | Maternal | N/S | 500/d | |||||
| 20 | Maternal | Placebo | ||||||
| 17 | Infant | N/S | 400/d | |||||
| Saadi et al. (49) | United Arab Emirates | Open-label randomized intervention trial | 45 | Maternal | D-2 | 60,000/mo | From delivery to 3 mo | All mothers received 600 mg/d calcium. All infants received 400 IU/d vitamin D-2.5 |
| 45 | Maternal | D-2 | 2000/d | |||||
| Takeuchi et al. (50) | Japan | Nonrandomized prospective intervention | 506 | Maternal | D-2 | 1200/d | From 1 wk after delivery to 5 wk | |
| Maternal | No intervention | |||||||
| Thiele et al. (51) | United States | Double-blind RCT | 8 | Maternal | D-3 | 3400/d + 400/d from prenatal vitamin | From 24–28 weeks of gestation to 4–6 wk postpartum | All mothers were encouraged to supplement their infants with 400 IU/d vitamin D.7 |
| 8 | Maternal | D-3 | 400/d from prenatal vitamin | |||||
| Wagner et al. (52) | United States | Pilot RCT | 9 | Maternal | D-3 | 6000/d + 400/d from prenatal vitamin | From 1 mo after delivery for 6 mo | |
| 10 | Maternal | D-3 | 0 + 400/d from prenatal vitamin | All infants received a multivitamin containing 300 IU/d vitamin D-3. | ||||
| Wheeler et al. (53) | New Zealand | RCT | 30 | Maternal | D-3 | 100,000/mo | From 4 to 20 wk postpartum | |
| 30 | Maternal | D-3 | 50,000/mo | |||||
| 30 | Maternal | Placebo | ||||||
| Infant bolus vs. daily supplementation | ||||||||
| Holst-Gemeiner et al. (54) | Germany | Nonrandomized prospective intervention | 11 | Infant | D-3 | 200,000 | Single bolus dose at birth | |
| 10 | Infant | D-3 | 1200/d | From day 2 to day 10 of life | ||||
| Huynh et al.4 (36) | Australia | Open-label RCT | 34 | Infant | D-3 | 50,000 | Single bolus dose within 48 h of birth | |
| 36 | Infant | D-3 | 400/d | From birth to 4 mo | Intervention dose provided in the form of a multivitamin. | |||
| Kumar et al. (55) | India | Double-blind RCT | 1039 | Infant | D-3 | 1400/wk | From 7 d to 6 mo | |
| 1040 | Infant | Placebo | ||||||
| Lagomarsino et al. (56) | Chile | Nonrandomized prospective intervention | 35 | Infant | D-3 | 600,000 | At 1st and 6th months1 of age | |
| 43 | Infant | D-3 | 400/d | From 15 d to 6 mo | ||||
| Moodley and Spector (57) | Mexico | Double-blind RCT | 516 | Infant | D-3 | 50,000 | Single dose at birth | |
| Infant | Placebo | |||||||
| Shajari et al. (58) | Iran | Randomized intervention trial | 30 | Infant | D-3 | 50,000 | Day 15 and day 60 after birth | |
| 30 | Infant | D-3 | 400/d | From 15 d to 3 mo | ||||
| 30 | Infant | D-3 | 200/d | |||||
| Shakiba et al.4 (37) | Iran | Randomized intervention trial | 30 | Infant | D-3 | 50,000 every 2 mo | At days 15–30, 2 mo, and 4 mo | |
| 45 | Infant | D-3 | 400/d | From days 15–30 to 6 mo | ||||
| 45 | Infant | D-3 | 200/d | |||||
| Shakiba et al. (59) | Iran | Nonrandomized controlled trial | 34 | Infant | D-3 | 30,000 | Single bolus dose within the 1st wk of life | Bolus supplementation was repeated after 1 mo if a 25(OH)D concentration >75 nmol/L was not obtained. If achieved, infants received 400 IU/d vitamin D-3. |
| 48 | Infant | D-3 | 400/d | Within 15 d to 4 mo | ||||
| Zeghoud et al. (60) | Algeria | Randomized intervention trial | 30 | Infant | D-3 | 600,000 | Single bolus dose at 15 d | |
| 15 | Infant | D-3 | 200,000 | Single bolus dose at birth | ||||
| 15 | Infant | D-3 | 100,000 every 3 mo | From birth to 6 mo | ||||
1
N/S, not specified; RCT, randomized controlled trial; 25(OH)D, 25-hydroxyvitamin D.
2
Unless otherwise stated, no additional vitamin D or micronutrient supplements were provided to either mothers or infants during the trial period.
3
Vitamin D supplementation form obtained from authors’ later paper (39).
4
Denotes trials eligible for inclusion in meta-analysis.
5
Specified in the authors’ later paper (29).
6
Sample size per intervention arm at randomization unclear; reported as total sample size at baseline.
7
Specified in the authors’ later paper (32).