Postnatal placental respiration

Effects of delayed cord clamping in very-low-birth-weight infants

OBJECTIVE

Delayed cord clamping (DCC) may be beneficial in very-preterm and very-low-birth-weight infants.

STUDY DESIGN

This study was a randomized unmasked controlled trial. It was performed at three centers of the NICHD (National Institute of Child Health and Human Development) Neonatal Research Network. DCC in very-preterm and very-low-birth-weight infants will result in an increase in hematocrit levels at 4 h of age. Infants with a gestational age of 24 to 28 weeks were randomized to either early cord clamping (<10 s) or DCC (30 to 45 s). The primary outcome was venous hematocrit at 4 h of age. Secondary outcomes included delivery room management, selected neonatal morbidities and the need for blood transfusion during the infants' hospital stay.

RESULT

A total of 33 infants were randomized: 17 to the immediate cord clamping group (cord clamped at 7.9±5.2 s, mean±s.d.) and 16 to the DCC (cord clamped at 35.2±10.1 s) group. Hematocrit was higher in the DCC group (45±8% vs 40±5%, P<0.05). The frequency of events during delivery room resuscitation was almost identical between the two groups. There was no difference in the hourly mean arterial blood pressure during the first 12 h of life; there was a trend in the difference in the incidence of selected neonatal morbidities, hematocrit at 2, 4 and 6 weeks, as well as the need for transfusion, but none of the differences was statistically significant.

CONCLUSION

A higher hematocrit is achieved by DCC in very-low-birth-weight infants, suggesting effective placental transfusion.

THIRD STAGE PRACTICES AND THE NEONATE

The third stage of labour is defined as the period following the completed delivery of the newborn until the completed delivery of the placenta and its attached membranes. Whilst to the exhausted labouring woman this stage may be an afterthought, it is a crucial time for fetal-to-neonatal transition. Major changes in anatomy and physiology occur in both mother and baby. It has also been described as ‘potentially the most hazardous part of childbirth, largely due to the risk of postpartum haemorrhage (PPH) on placental separation. Despite this, the current management guidelines are based on an ‘eclectic combination of historical, anecdotal, philosophical and research-based factors.

Neonatal transitional physiology: a new paradigm

Early clamping of the umbilical cord at birth, a practice developed without adequate evidence, causes neonatal blood volume to vary 25% to 40%. Such a massive change occurs at no other time in one's life without serious consequences, even death. Early cord clamping may impede a successful transition and contribute to hypovolemic and hypoxic damage in vulnerable newborns. The authors present a model for neonatal transition based on and driven by adequate blood volume rather than by respiratory effort to demonstrate how neonatal transition most likely occurs at a normal physiologic birth.

Umbilical cord clamping: beliefs and practices of American nurse-midwives

The optimal time for umbilical cord clamping after birth remains a critical unknown fact that has implications for the infant, the mother, and science. A national survey was conducted using a randomized sample (n = 303) of the active membership of the ACNM to determine cord clamping practices and beliefs of American nurse-midwives. The response rate was 56%. The respondents fell into three cord clamping categories: early (EC) or before 1 minute (26%); intermediate (IC) or 1 to 3 minutes (35%); and late (LC) or after pulsations cease (33%). The EC group believes that early clamping facilitates management of the newborn. The IC group believes that a moderate delay of clamping allows for a gradual transition to extrauterine circulation, although many think that the timing of cord clamping is not significant. The LC group have strongly held beliefs that late clamping supports physiologic birth processes. The majority of CNMs (87%) place the baby on the mother's abdomen immediately after birth and 96% avoid clamping a nuchal cord whenever possible. Although Varney's Midwifery was cited most frequently as a reference, 78% of the respondents listed no references reflecting, in part, the absence of evidence-based recommendations for cord clamping practices.

Evaluation of the meta-analyses on the effects, on both mother and baby, of the various components of 'active' management of the third stage of labour

In their comprehensive review of controlled trials, Prendiville and Elbourne (1989) used the technique of meta-analysis to study the effects, on both mother and baby, of various aspects of third stage management, acknowledging some of the shortcomings of the trials used. This paper questions some of the conclusions which these authors drew and, drawing on other evidence (some of which has been published since the review), puts forward alternative interpretations of some of the meta-analyses. Reference is also made to the updated meta-analyses in the Cochrane Pregnancy and Childbirth Database (Elbourne, 1994a-h). In addition, this paper examines the extent to which the findings of the Bristol and Dublin third stage trials (Prendiville et al, 1988; Begley, 1990) add to our understanding of what is effective care during the third stage of labour.

The Bristol third stage trial: active versus physiological management of third stage of labour

OBJECTIVE

To compare the effects on fetal and maternal morbidity of routine active management of third stage of labour and expectant (physiological) management, in particular to determine whether active management reduced incidence of postpartum haemorrhage.

DESIGN

Randomised trial of active versus physiological management. Women entered trial on admission to labour ward with allocation revealed just before vaginal delivery. Five months into trial high rate of postpartum haemorrhage in physiological group (16.5% v 3.8%) prompted modification of protocol to exclude more women and allow those allocated to physiological group who needed some active management to be switched to fully active management. Sample size of 3900 was planned, but even after protocol modification a planned interim analysis after first 1500 deliveries showed continuing high postpartum haemorrhage rate in physiological group and study was stopped.

SETTING

Maternity hospital.

PARTICIPANTS

Of 4709 women delivered from 1 January 1986 to 31 January 1987, 1695 were admitted to trial and allocated randomly to physiological (849) or active (846) management. Reasons for exclusion were: refusal, antepartum haemorrhage, cardiac disease, breech presentation, multiple pregnancy, intrauterine death, and, after May 1986, ritodrine given two hours before delivery, anticoagulant treatment, and any condition needing a particular management of third stage.

INTERVENTIONS

All but six women allocated to active management actually received it, having prophylactic oxytocic, cord clamping before placental delivery, and cord traction; whereas just under half those allocated to physiological management achieved it. A fifth of physiological group received prophylactic oxytocic, two fifths underwent cord traction and just over half clamping of the cord before placental delivery.

ENDPOINT

Reduction in incidence of postpartum haemorrhage from 7.5% under physiological management to 5.0% under active management.

MEASUREMENTS AND MAIN RESULTS

Incidence of postpartum haemorrhage was 5.9% in active management group and 17.9% in physiological group (odds ratio 3.13; 95% confidence interval 2.3 to 4.2), a contrast reflected in other indices of blood loss. In physiological group third stage was longer (median 15 min v 5 min) and more women needed therapeutic oxytocics (29.7% v 6.4%). Apgar scores at one and five minutes and incidence of neonatal respiratory problems were not significantly different between groups. Babies in physiological group weighed mean of 85 g more than those in active group. When women allocated to and receiving active management (840) were compared with those who actually received physiological management (403) active management still produced lower rate of postpartum haemorrhage (odds ratio 2.4;95% CI1.6 to 3.7).

CONCLUSIONS

Policy of active management practised in this trial reduces incidence of postpartum haemorrhage, shortens third stage, and results in reduced neonatal packed cell volume.

The effects of routine oxytocic administration in the management of the third stage of labour: an overview of the evidence from controlled trials

Recent claims that routine active management of the third stage of labour increases rather than decreases maternal and neonatal morbidity have prompted us to conduct a systematic review of the relevant controlled trials. In this paper we have analysed data derived from a total of nine published reports of controlled trials in which an oxytocic drug was compared with either a placebo or no routine prophylactic. Oxytocic drugs used routinely appear to reduce the risk of postpartum haemorrhage by about 40% (typical odds ratio 0.57, 95% confidence interval 0.44-0.73) implying that for every 22 women given such an oxytocic, one postpartum haemorrhage could be prevented. The available data are insufficient to assess the possible effects of this policy on the incidence of retained placenta, hypertension and other possible adverse effects.