Table 2.
Prospective studies reporting iron-related risk factors of GDM.
| Factors | Study | Research Design | Comparison Groups | Adjusted RR/OR (95% CI) |
|---|---|---|---|---|
| Dietary heme iron intake | Qiu et al. (2011) [126] | Prospective cohort; 3158 pregnant women |
Heme iron intake levels (≥1.52 vs. <0.48 mg per day) | 3.31 (1.02–10.72) |
| Bowers et al. (2011) [127] | Prospective study; 13,475 pregnant women |
Median heme iron intake levels (1.60 vs. 0.66 mg per day) | 1.58 (1.21–2.08) |
|
| Dietary non-heme iron intake | Qiu et al. (2011) [126] | Prospective cohort; 3158 pregnant women |
Non-heme iron intake levels (≥12.98 vs. <0.10 mg per day) | 0.61 (0.31–1.18) |
| Bowers et al. (2011) [127] | Prospective study; 13,475 pregnant women |
Median heme iron intake levels (45.33 vs. 7.58 mg per day) | 0.97 (0.78–1.20) |
|
| Iron supple-mentation | Bowers et al. (2011) [127] | Prospective study; 13,475 pregnant women |
Median Iron supplementation levels (60.00 vs. 0 mg per day) | 1.04 (0.84–1.28) |
| Chan et al. (2009) [128] |
RCT; 1164 pregnant women with Hb level between 8–14 g/dl | 60 mg daily iron supplementation vs. placebo group | 1.04 (0.70–1.53) |
|
| Zhang et al. (2021) [129] | Prospective cohort; 2117 pregnant women |
>60 mg daily iron supplementation during the second trimester vs. non-users |
1.43 (1.06, 1.92) |
|
| Zhang et al. (2021) [130] | Prospective cohort; 5101 pregnant women |
>30 mg daily iron supplementation for more than 3 months vs. non-users |
1.53 (1.21–1.93) |
|
| Serum ferritin | Rawal et al. (2017) [134] |
Prospective case–control study; 107 women with GDM and 214 controls | Highest vs. lowest quartile of serum ferritin level | 2.43 (1.12–5.28) |
| Bowers et al. (2016) [135] | Prospective case–control study; 350 women with GDM and 349 controls | Highest vs. lowest quartile of serum ferritin level | 2.22 (1.23–4.01) |
|
| Khambalia et al. (2016) [136] | Prospective cohort study; 4420 pregnant women | Serum ferritin level <12 μg/L vs. normal | 0.43 (0.23–0.78) |
|
| Serum sTfR | Rawal et al. [134] |
Prospective case–control study; 107 women with GDM and 214 controls | Highest vs. lowest quartile of serum sTfR level | 1.00 (0.45–2.20) |
| Bowers et al. [135] | Prospective case–control study; 350 women with GDM and 349 controls | Highest vs. lowest quartile of serum sTfR level | 1.48 (0.82–2.70) |
|
| Khambalia et al. (2016) [136] | Prospective cohort study; 4420 pregnant women | Serum sTfR level >21 nmol/L vs. normal | 1.25 (0.82–1.92) |
|
| Serum hepcidin | Rawal et al. (2017) [134] |
Prospective case–control study; 107 women with GDM and 214 controls | Highest vs. lowest quartile of serum hepcidin level | 2.61 (1.07–6.36) |
Abbreviations: GDM, gestational diabetes mellitus; sTfR, soluble transferrin receptor.