Syed et al. BMC Public Health 2011, 11(Suppl 3):S2 http://www.biomedcentral.com/1471-2458/11/S3/S2 Page 7 of 12 Experimental Control Risk Ratio Study or Subgroup Events Total Events Total Weight M-H, Fixed, 95% CI 4.1.1 Cohort Study Gonzalez-Quintero 2007 1 48 1 110 10.7% 2.29 [0.15, 35.88] Temple 2002 2 2030 4 1188 89.3% 0.29 [0.05, 1.60] Subtotal (95% CI) 2078 1298 100.0% 0.51 [0.14, 1.88] Total events 3 5 Heterogeneity: Chi² = 1.56, df = 1 (P = 0.21); I² = 36% Test for overall effect: Z = 1.02 (P = 0.31) Total (95% CI) 2078 Total events 3 5 Heterogeneity: Chi² = 1.56, df = 1 (P = 0.21); I² = 36% Test for overall effect: Z = 1.02 (P = 0.31) Test for subgroup differences: Not applicable 1298 100.0% 0.51 [0.14, 1.88] Risk Ratio M-H, Fixed, 95% CI 0.01 0.1 1 10 Favours experimental Favours control 100 Figure 3 Patients with optimal control versus suboptimal control. Outcome: Pooled data for stillbirth. (6) The effectiveness of continuous infused insulin versus multiple dose insulin Seven studies focused on the comparison of continuous subcutaneous insulin versus conventional multiple injec- tions of insulin. Six of these studies were intervention studies [16-21] and one was an observational study [47]. Of the six intervention studies [16-21] five were on type 1 diabetics and one included both type 1 and 2 dia- betics [20]. Data from one study could not be added as the full text of the article was unavailable [17]. The single observational study retrieved for this com- parison did not report any significant effects on perina- tal mortality (p-value = not significant). Data for stillbirths from the intervention studies was pooled and the following non-significant effect was seen (OR= 3.17, 95% CI 0.71-14.28) (figure 5). In conclusion, three RCTs [16,20,21] and 2 quasi RCTs [18,19] focused on the intervention of continuous subcutaneous insulin infusion versus conventional mul- tiple insulin injections. None reported significant results. The meta-analysis did not reveal statistically significant impact on stillbirth risk. Studies provided a moderate level of evidence for showing no significant benefit of continuous subcutaneous insulin compared to multiple dose therapy on risk of stillbirths. (7) Comparisons between different types of insulin Four studies; two RCTs [14], [22] one retrospective cohort [78] and one prospective cohort study [63] on compared different types of insulin. Of the two rando- mized trials, Hod et al. 2008 [14] compared the effect of insulin aspart versus human insulin. The comparison of Experimental Control Study or Subgroup Events Total Events Total Weight 4.2.1 Cohort Study Bannerjee 2004 16 164 24 76 78.3% Mirghani 2001 9 56 5 15 18.8% Temple 2002 2 48 2 110 2.9% Subtotal (95% CI) 268 201 100.0% Total events 27 31 Heterogeneity: Chi² = 4.08, df = 2 (P = 0.13); I² = 51% Test for overall effect: Z = 3.93 (P < 0.0001) Total (95% CI) 268 201 100.0% Total events 27 31 Heterogeneity: Chi² = 4.08, df = 2 (P = 0.13); I² = 51% Test for overall effect: Z = 3.93 (P < 0.0001) Test for subgroup differences: Not applicable Risk Ratio M-H, Fixed, 95% CI 0.31 [0.17, 0.55] 0.48 [0.19, 1.23] 2.29 [0.33, 15.80] 0.40 [0.25, 0.63] 0.40 [0.25, 0.63] Figure 4 Patients with optimal control versus suboptimal control. Outcome: Pooled data for perinatal death. Risk Ratio M-H, Fixed, 95% CI 0.01 0.1 1 10 100 Favours experimental Favours control