Labour Augmentation by Means of Oxytocin - Obstetric Outcome and Women's Experiences

In contemporary handling of labouring women in the western world, it has become extremely common to intervene through "active" or disciplined" management (Enkin et al., Widela et al., Gerdhardstein et al., Frigoletto et al). It is a widespread routine - and potential side effects will therefore have a great impact. The use of the hormone oxytocin to enhance and speed up labour is the most common method, but the sparse scientific data regarding its effect are inconsistent and mostly demonstrate uncertain and sometime side effects (Thornton \& Lilford, Frazer 1994, 1998, Cammu \& Van Eeckhout).

The effects, when evaluated, are short-term effects of maternal (obstetric) and fetal outcomes. The studies performed have mostly aimed to investigate whether the active management can reduce the rate of caesarean sections. However, in a meta-analysis of four randomised studies of the effects of oxytocin as intervention in spontaneous labour (Frazer), no significant reduction in the incidence of caesarean section, instrumental deliveries, and use of analgetics or hyper stimulation of labour was found. The only statically significant differences were in side effects: an increased incidence of discomfort and of pain in the group given oxytocin. In this meta-analysis, no significant differences in fetal conditions between the groups were found.

Only one of the studies found sought the women's view on the augmentation procedures (Enkin). Over half of the women who were interviewed, said that the oxytocin treatment was unpleasant and indicate that they would like to try without the drug when giving birth the next time. Over 80% felt that it had increased the amount of pain that they had experienced.

In spite of poor evidence of benefits, around half of birth giving women in Sweden receive oxytocin during labour and in some other countries, far more than that (Waldenström, O'Driscoll, Enkin). It has become the standard care of treating labours with slow progress. According to an investigation by the Swedish National Board of Health and Welfare (Socialstyrelsen 1996), the indications for oxytocin use and the amounts administered are not systematically recorded, and the assessments of its effects are even less well recorded. This makes evaluation by using existing documents very unreliable, and randomised controlled studies.

Aims of the study

The aims of the study are:

• To study the effects of oxytocin treatment vs no or delayed oxytocin treatment on the obstetrical and fetal outcome of spontaneous, but prolonged labour. Primary outcome is rate of spontaneous vaginal deliveries. Secondary outcome are length of labour, postpartum haemorrhage, sphincter lacerations, Apgar score, perceived pain and sense of safety.
• To study labour experiences in women exposed to oxytocin treatment vs women without oxytocin treatment.

Methods

The planned study design is a randomised controlled study with healthy women with normal pregnancies and spontaneous labour, where labour progression is deemed to be prolonged.

Inclusion criteria

Healthy women with full-term, normal pregnancies, spontaneous onset of active labour (effaced cervix and minimum 4 cm dilated) and about to give birth to their first child.

Exclusion criteria

Women with multiple pregnancies, complicated pregnancies, maternal disease during pregnancies, ruptured membranes for more than 2 hours before onset of labour contractions, and fetus in breech presentation.

Sample size calculation

A sample size of 247 in each group is needed to show a difference in spontaneous vaginal deliveries from 81,2% to 90% with a 2-sided test, alpha=0,05 and 80% power.

Procedure

Women fulfilling the criteria as described above are regarded as potential study subjects. Information about the study is distributed during the last trimester at the antenatal clinic. On arrival at the delivery ward, all women fulfilling these criteria are again informed about the study and asked for consent to participate. The progression of labour is thoroughly followed and documented for women who have agreed to participate. If the labour is prolonged during the active phase and is classified as inertia, i.e. with no further opening of the cervix for 2 hours or less than 1 cm in 3 hours, the subject are randomly allocated to either labour augmentation by means of oxytocin infusion within twenty minutes (standard care) or to expectancy and observation another 3 hours (experimental group) If the subjects in the experimental group after the 3 hours still do not progress in their labour, a reassessment regarding the need for labour augmentation is done. Women fulfilling inclusion criteria, and who have agreed to participate, but whose labours proceed normally, are followed according the same protocol, hence serving as external controls.

Assessment and follow-up

The handling of the participants will be done according to a standard protocol holding continuous documentation of the progression of labour, of the amount of oxytocin administered, of the analgesia used and of the obstetric outcome (caesarean section, instrumental vaginal delivery, length of labour, Apgar score etc). At the inclusion in the study, the women assess their expectancies, their perceived pain and sense of safety, using a visual analogue scale. Pain and sense of safety is then assessed at several occasions during and after delivery.

In order to study the women's retrospective perceptions of their labour, they receive a questionnaire regarding their perceived experience one month post partum. This instrument focus on perceived pain, perceived safety, perceived participation in decision-making, sense of control and patient satisfaction. This questionnaire also contains questions regarding breast-feeding and a separate part is to be answered by the father. The latter part holding questions about the fathers' levels of preparation for the delivery, and his expectations and experiences as a supportive person in the labour room. A subgroup of the subjects (24 + 24) - oxytocin exposed and unexposed women - will be interviewed at one and four months after birth, using a qualitative interview method.

Assessment of the baby is done at birth through Apgar scoring, fetal pH and base excess from the umbilical cord blood. In addition to this, a subgroup of the neonates will get their motor activity, heart frequency and respiration activity continuously registered during the first night after birth. This is done with the help of a so-called "sleep-box"

Safety

Three hours after the inclusion in the study, a reassessment of the progress of the labour is performed to evaluate whether the progression is satisfactory, or if oxytocin for those assigned to the experimental group is assessed to be required (procedures).

Reassessments are then done regularly with 2-3 hours interval.

Ethics

Making a randomised, clinical study with care/treatment group and non-care/non-treatment group, always raises the question whether it is good ethics or not to abstain from the presently applied care programme. In this case, scientific data regarding the beneficial outcomes are ambiguous and inconsistent, and it is thus not obvious which of the procedures offered is "best" for the woman and the child. With this background, performing the study including well informed subjects and aiming at evaluating effects of standard procedures, must be considered ethically acceptable.

Importance of the study

There are few controlled studies on the effects of the standard procedure of treating slow labour progression with oxytocin and these show conflicting results. Considering this widespread treatment involving large population of women and newborns, it is of great importance to evaluate potential benefits and side effects in controlled studies. Knowledge about this is especially important in the reorganisation and rationing of resources within obstetric services. In the attempts to shorten women's hospital stays, the shortening of duration of labour has sometimes been considered a means to make obstetric care more cost-efficient and this fact makes independent evaluation of the care even more important.

Furthermore, patients have the right to get evidence based care and treatment. This study will hopefully contribute to a better evidence based handling of women in labour who are subjected to secondary inertia, and in addition it will give us more information about fathers' experiences, which will help us enhance the care of the next-to-kin of the labouring woman.

References

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