Comment: The quality of evidence is downgraded by study quality (unclear allocation concealment, no blinding, incomplete outcome data, selective reporting) and by imprecise results.
A Cochrane review included 15 studies with a total of 3911 mothers and their babies. There were no significant differences between early versus late cord clamping groups for the primary outcome of severe postpartum haemorrhage (RR 1.04, 95% CI 0.65 to 1.65; 5 trials n=2066 women with a late clamping event rate (LCER) of ˜3.5%, I2 0%) or for postpartum haemorrhage of 500 mL or more (RR 1.17 95% CI 0.94 to 1.44; 6 trials, n=2260 with a LCER of ˜12%, I2 0%). Mean blood loss was reported in only two trials with data for 1345 women, with no significant differences seen between groups. There were no significant differences between early and late clamping for the primary outcome of neonatal mortality in 2 trials (n=381), or for most other neonatal morbidity outcomes, such as Apgar score less than seven at five minutes or admission to the special care nursery or neonatal intensive care unit. Mean birthweight was significantly higher in the late, compared with early, cord clamping (101 g increase 95% CI 45 to 157, random-effects model, 12 trials, n=3139 infants, I²=62%). Fewer infants in the early cord clamping group required phototherapy for jaundice than in the late cord clamping group (RR 0.62, 95% CI 0.41 to 0.96; 7 trials, 2324 infants with a LCER of 4.36%, I²=0%). Haemoglobin concentration in infants at 24 to 48 hours was significantly lower in the early cord clamping group (MD -1.49 g/dL, 95% CI -1.78 to -1.21; 884 infants, I²=59%). This difference in haemoglobin concentration was not seen at subsequent assessments. However, improvement in iron stores appeared to persist, with infants in the early cord clamping over twice as likely to be iron deficient at 3 to 6 months compared with infants whose cord clamping was delayed (RR 2.65 95% CI 1.04 to 6.73, 5 trials, n=1152, I²=82%).
A systematic review including 15 studies (8 RCTs, n=1719 and 7 CTs, n=302) with a total of 1912 subjects was abstracted in DARE. Late clamping was associated with a significant increase in haematocrit at 6 hours (WMD 4.16%, 95% CI 0.83 to 7.49; 2 studies, n=494), 24 to 48 hours (WMD 10.01%, 95% CI 4.10 to 15.92; 4 studies, n=341), but not 6 months after delivery (WMD 0.10%, 95% CI -0.62 to 0.82; 1 study, n=305). Late clamping was associated with an increased ferritin concentration 2 or 3 months after delivery (WMD 17.89 mg/L, 95% CI 16.58 to 19.21; 2 studies, n=144) and an increase in stored iron measurements in 6-months-olds (WMD 19.90, 95% CI 7.67 to 32.13; 1 study, n=315). Babies with late clamping were at increased risk of experiencing asymptomatic polycythaemia at 24 to 48 hours (RR 3.82, 95% CI: 1.11, 13.21; based on 3 studies reporting at least one event).