Abstract: We included four trials (4608 women), but only two studies contributed data to the review's analyses (n = 4472). The studies contributing data were assessed as of high risk of bias overall. One of these studies was cluster-randomised and conducted in a low-income country and the other study was carried out in a high-income country. All four included studies assessed blood loss in the third stage of labour. Birth attendants estimated blood loss in two trials. The third trial assessed the hematocrit level on the second day postpartum to determine the effect of the bleeding. The fourth study measured PPH ≥ 500 mL. Nipple stimulation versus no treatment One study (4385 women) compared the effect of suckling versus no treatment. Blood loss was not measured in 114 women (59 in control group and 55 in suckling group). After excluding twin pregnancies, stillbirths and neonatal deaths, the main analyses for this trial were performed on 4227 vaginal deliveries. In terms of maternal death or severe morbidity, one maternal death occurred in the suckling group due to retained placenta (risk ratio (RR) 3.03, 95% confidence interval (CI) 0.12 to 74.26; one study, participants = 4227; very low quality evidence); severe morbidity was not mentioned. Severe PPH (≥ 1000 mL) was not reported in this study. The incidence of PPH (≥ 500 mL) was similar in the suckling and no treatment groups (RR 0.95, 95% CI 0.77 to 1.16; one study, participants = 4227; moderate quality). There were no group differences between nipple stimulation and no treatment regarding blood loss in the third stage of labour (mean difference (MD) 2.00, 95% CI -7.39 to 11.39; one study, participants = 4227; low quality). The rates of retained placenta were similar (RR 1.01, 95% CI 0.14 to 7.16; one study, participants = 4227; very low quality evidence), as were perinatal deaths (RR 1.06, 95% CI 0.57 to 1.98; one study, participants = 4271; low quality), and maternal readmission to hospital (RR 1.01, 95% CI 0.14 to 7.16; one study, participants = 4227; very low quality). We downgraded the evidence for this comparison for risk of bias concerns in the one included trial (inappropriate analyses for cluster design) and for imprecision (wide CIs crossing the line of no difference and, for some outcomes, few events). Many maternal secondary outcomes (including side effects) were not reported. Similarly, most neonatal secondary outcomes were not reported. Nipple stimulation versus oxytocin Another study compared the effect of nipple stimulation (via a breast pump) with oxytocin. Eighty-seven women were recruited but only 85 women were analysed. Severe PPH ≥ 1000 mL and maternal death or severe morbidity were not reported. There was no clear effect of nipple stimulation on blood loss (MD 15.00, 95% CI -24.50 to 54.50; one study, participants = 85; low quality evidence), or on postnatal anaemia compared to the oxytocin group (MD -0.40, 95% CI -2.22 to 1.42; one study, participants = 85; low quality evidence). We downgraded evidence for this comparison due to risk of bias concerns in the one included trial (alternate allocation) and for imprecision (wide CIs crossing the line of no difference and small sample size). Many maternal secondary outcomes (including side effects) were not reported, and none of this review's neonatal secondary outcomes were reported. None of the included studies reported one of this review's primary outcomes: severe PPH ≥ 1000 mL. Only one study reported on maternal death or severe morbidity. There were limited secondary outcome data for maternal outcomes and very few secondary outcome data for neonatal outcomes. There was no clear differences between nipple stimulation (suckling) versus no treatment in relation to maternal death, the incidence of PPH (≥ 500 mL), blood loss in the third stage of labour, retained placenta, perinatal deaths or maternal readmission to hospital. Whilst these data are based on a single study with a reasonable sample size, the quality of these data are mostly low or very low. There is insufficient evidence to evaluate the effect of nipple stimulation for reducing postpartum haemorrhage during the third stage of labour and more evidence from high-quality studies is needed. Further high-quality studies should recruit adequate sample sizes, assess the impact of nipple stimulation compared to uterotonic agents such as syntometrine and oxytocin, and report on important outcomes such as those listed in this review.

Plain-language summary: We searched for evidence on 15 July 2015 and included four randomised controlled studies with 4608, women but only two of the studies had useable data. We assessed both studies contributing outcome data as being at a high risk of bias. One study compared the effect of the baby suckling immediately after birth with no intervention. Another study compared nipple stimulation (with a breast pump) versus oxytocin injection. Neither study reported postpartum haemorrhage. Side effects of the treatments were not reported. Similarly, there was limited information on other consequences for women and their babies. When comparing nipple stimulation (suckling) with no breastfeeding, there were no clear differences in terms of the number of maternal deaths. The incidence of severe maternal illness was not reported. One woman in the suckling group died as a result of a retained placenta. Blood loss greater than or equal to 500 mL, retained placenta, perinatal deaths and maternal readmission to hospital were not clearly different between those who breast fed and those who did not. While these data were based on a single study with a reasonable sample size (4227 women), the results were mostly of low or very low quality due to concerns related to data analysis and study methodology. Our comparison of nipple stimulation (using a breast pump) versus oxytocin included one small study involving 85 women only. There was no clear difference between the groups in relation to blood loss or postnatal anaemia. These results were of low quality due to our concerns about the way the trial was conducted and its small size. There is insufficient evidence to evaluate the effectiveness of nipple stimulation for reducing bleeding during the third stage of labour and more evidence from high-quality studies is warranted. Future randomised clinical trials, with sufficient sample sizes should assess the impact of nipple stimulation in comparison to agents that stimulate the uterus such as syntometrine or oxytocin alone and report on important outcomes such as those listed in this review.