Table 9. The effect of Vitamin D supplementation in gestation on offspring birth weight (BW) – Intervention studies.
| First Author, year |
Risk of bias |
Setting | Randomisation | Adjustments/ confounders accounted for |
Number of weeks gestation when 25(OH)D was measured | Mean (SD)/ Mean (SE)* or median (IQR) maternal 25(OH)D concentration (nmol/l) | Mean (SD) or Mean (SE)* birth weight (g) in un-supplemented group | Mean (SD) or Mean (SE)* birth weight (g) in supplemented group | Conclusion | ||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Brooke, 1980 4 | −2 (high) | London, UK, n=126, all Asian women | Double-blinded Randomised to either placebo (n=67) or 1000 IU/day of vitamin D2 in last trimester (n=59) | Nil, but groups of similar age, height, parity, offspring sex, length of gestation | 28-32 weeks and at birth | At allocation 25(OH)D=20.1 (1.9)* At term, Controls 25(OH)D=16.2 (2.7)* At term, supplemented group 25(OH)D =168.0 (12.5)* | 3034 (64) | 3157 (61) | No significant difference in BW between groups p>0.05 | ||
| Marya, 1981 5 | −6 (high) | Rohtak, India n=120 women | 3 arms: Randomised to either no supplement (n=75) or 1,200 IU vitamin D + 375 mg calcium/ dayΔ 3 throughout the 3rd trimester (n=25); or oral 600,000 IU vitamin D2; 2 doses in 7th and 8th months gestation (n=20) | Nil | Not measured | Not measured | 2730 (360) | 1200IU/+ ca=2890 (320) 600,000 IU=3140 (450) | BW significantly higher in those taking supplements and highest in the 600,000 IU group p=0.05 for un-supplemented vs. 1200 IU group p=0.001 for non-supplemented vs. 600,000 IU group | ||
| Congdon, 1983 22 | −9 (high) | Leeds, UK n=64, all Asian women | Either 1000 IU vitamin D plus calcium (calcium dose not given) daily in the 3rd trimester (n=19) or no supplement (n=45) | Nil, but groups similar in terms of maternal age, infant sex, gestation length, birth weight | Not measured | Not measured | 3056 (59)* | 3173 (108)* | No significant difference in BW between the two groups (p value not given) | ||
| Delvin, 1986 7 | −2 (high) | Lyon, France n=40 women | Randomised to either no supplement (n=20) or 1000 IU vitamin D3/day during 3rd trimester (n=20) | Nil Groups similar in terms of maternal age and parity. All deliveries occurred in the same month (June) | At recruitment and at delivery | Mean (SD) 25(OH)D in suppl. group |
Mean (SD) 25(OH)D in un-sup group |
Not given | Not given | No significant difference in BW between the 2 groups (p value not given) | |
| At recruitment | 54.9 (10.0) | 27.5 (10.0) | |||||||||
| Delivery | 64.9 (17.5) | 32.4 (20.0) | |||||||||
| Mallet, 1986 8 | −3 (high) | Rouen, France n=77, all white women | 3 arms: Randomised to either no supplement (n=29) or 1,000 IU vitamin D/day△ in last 3 months of pregnancy (n=21), or single oral dose of vitamin D△ 200,000 IU in 7th month (n=27) | Nil, but groups of similar maternal age, parity, calcium intake and frequency of outdoors outings | During labour (February and March) | Overall mean not given According to group: Un-supplemented=9.4 (4.9) 1000 IU/day=25.3 (7.7) 200,000 IU=26.0 (6.4) |
3460 (70) | 1000 IU/day = 3370 (80) 200,000 IU = 3210 (90) | No significant difference in BW between the 3 groups p value not given | ||
| Marya, 1988 6 | −2 (high) | Rohtak, India n=200 women | Randomised to either no supplement (n=100) or oral 600,000 IU vitamin D3; 2 doses in 7th and 8th months gestation (n=100) | Nil, but groups had similar maternal age, maternal height, maternal height, parity, haemoglobin, calcium intake and vitamin D intake | Not measured | Not measured directly, but mean daily vitamin D intake given as follows: Un-supplemented=35.71 (6.17) IU/day Supplemented group=35.01 (7.13) IU/day |
2800 (370) | 2990 (360) | BW significantly higher in the supplemented group p<0.001 | ||
| Kaur, 1991 98 | −7 (high) | Rohtak, India n=50 women | Randomised to either no supplement (n=25) or oral 60,000 IU vitamin D3; 2 doses in 6th and 7th month gestation (n=25) | Nil, but groups had similar maternal age, maternal weight, length of gestation, parity and haemoglobin | Not measured | Not measured | 2756 (60)* | 3092 (90)* | BW significantly higher in the supplemented group p<0.001 | ||
| Yu, 2009 96 | 5 (low) | London, UK n=179 women | 3 arms Randomised to either no supplement (n=59) or oral vitamin D2 800 IU/day vitamin from 27 weeks onwards (n=60), or a single 200,000 IU calciferol at 27 weeks gestation (n=60) Each group contained equal numbers of 4 ethnic groups (Caucasian, Black, Asian, Middle Eastern) |
Nil No significant difference in baseline characteristics across the 3 groups |
Measured at 26-27 weeks and again at delivery | 27 wks | Delivery | Not given | Not given | No significant difference in BW across the 3 groups | |
| No sup | 25 (21-38) | 27 (27-39) | |||||||||
| 800 IU daily | 26 (20-37) | 42 (31-76) | |||||||||
| single sup | 26 (30-46) | 34 (30-46) | |||||||||
| Hollis, 2011 97 | 10 (low) | Charleston, USA | 3 arms Randomised to either oral vitamin D3 400 IU/day (n=111) or 2000 IU/day (n=122) or 4000 IU/day (n=117) from 12-16 weeks gestation until delivery | Nil | Measured at baseline, then monthly and at delivery | Mean of measurements between 20-36 weeks | delivery | No un-supplemented group. All groups received some form of vitamin D3 supplementation | 400IU/day = 3221.8 (674.9) 2000 IU/day=3360.1 (585.0) 4000 IU/day=3284.6 (597.6) |
No significant difference in BW across the 3 groups (p=0.23) | |
| 400 IU daily | 79.1 (29.5) | 78.9 (36.5) | |||||||||
| 2000 IU daily | 94.4 (26.1) | 98.3 (34.2) | |||||||||
| 4000 IU daily | 110.8 (28.3) | 111.0 (40.4) | |||||||||
△ = not known whether supplementation was vitamin D2 or vitamin D3