Normal Birth - What are the Chances?

Also by Sally Tracy Article : It's happening - midwifery led maternity services at last! On the same subject Birth Intervention Parents

by Sally Tracy
		Sally trained as a midwife in New Zealand following the birth of her fourth child. Since her return to Australia she has been involved in research and has worked in both hospital and community settings. She was a research midwife with the Australian Midwifery Action Project (AMAP), and is enrolled at UTS in the inaugural Professional Doctorate in Midwifery. She is currently a senior research midwife at the Centre for Family Health and Midwifery, UTS.

Based on the findings of a study by Christine Roberts, Sally Tracy & Brian Peat.

Rates for obstetric intervention among private and public patients in Australia: a population based descriptive study. BMJ 2000; 321: 137-141

Australian maternity care has features of the British and American systems; all women are covered by national health insurance which provides free maternity care for public women in public hospitals but about one-third take out private medical insurance or pay for private obstetric care (private patients). Private women receive antenatal care from their chosen obstetrician in private rooms and give birth either at a private or public hospital. Public women attend antenatal clinics at public hospitals where care is provided by rostered midwives, residents, registrars and staff obstetricians. According to research undertaken in Victoria in 1994, Australian women choose their maternity care depending on their knowledge of what is available, whether or not they can meet the costs of private insurance or private care, and their proximity to services (Brown et al 1994). Currently in Australia, the national insurance system known as Medicare does not fund midwives to give care for women in childbirth. This means in effect, that women can choose a doctor they know for their labour and birth, but not a midwife, unless they are prepared to pay all costs themselves. (Having said this, there is now a very successful model where this is no longer the case - for example the Community Midwifery Programme, Western Australia CMPWA.)

Current research shows that Australia has in fact a two-tiered health system. The first tier includes heavily subsidised health services that are accessible to the rich and poor alike, and the second, the less heavily subsidised services which are consequently less accessible to the poor. People on low incomes are considerably less likely to use specialist medical practitioner services when compared to those on higher incomes. Several studies have shown that those on the top income quintile are 64% more likely to visit a medical specialist than those in the bottom income quintile (Scott 1996).

More than 66% of all specialists in obstetrics work in private practice. The remaining specialist medical practitioner services are provided free of charge through outpatient clinics at public hospitals.

There is no doubt that it is considered a 'status symbol' to be able to afford a private obstetrician for pregnancy and birth in Australia. Continuity of midwifery care, on the other hand, is neither encouraged nor funded as a mainstream service in Australia at present and midwives on the whole remain invisible.

The Senate Inquiry into Childbirth Procedures (1999) in Australia heard many submissions that high caesarean rates in the private sector are probably because large numbers of high-risk women take out private health insurance for pregnancy care. [more information]

We couldn't find data to support this assertion, but we did find two other Australian studies that reported an association between obstetric interventions and medical insurance status (Shorten and Shorten 1999, Cary 1990). According to the latest Australian national statistics, a fifth of all babies are surgically removed from their mothers via caesarean section (20.3%); and another 11.3% are delivered by obstetricians using either vacuum or forceps (AIHW 2000).

We feel that women should have equal access to quality maternity services, and that information on the outcomes associated with private and public care should be available and may possibly influence those choices.

In 2000 we undertook two studies. The first was to determine the obstetric intervention rates for private and public women in Australia, a population based descriptive study. This paper is based on the findings of the first paper published in the BMJ in July 2000 and can be accessed at the BMJ website.

The second study was to determine the trends in labour and birth interventions among low-risk women in an Australian population. This was published in the Australian and New Zealand Journal of Obstetrics and Gynaecology, in 2002.

In the first study we aimed to compare the characteristics of all women who paid for private health insurance, or a private obstetrician, with women who had no insurance and gave birth in public hospitals. By comparing maternal demographic and clinical factors among public and private women we were able to determine whether or not the women who had private care were different from those in the public system. The maternal factors included age, parity, and medical conditions - any or none reported; obstetric complications - any or none reported. Overall intervention rates included the rates of epidural and episiotomy; and the type of labour - whether it was spontaneous, induced or augmented. We also looked to see if women had no labour and that was described as an elective caesarean section. The birth outcomes included vaginal; forceps or vacuum; caesarean section before or after labour. Infant factors available for analyses included presentation, multiple birth, gestational age, birth weight and birth weight percentile.

Then we compared the obstetric intervention rates among the women who were medically defined as 'low-risk'. We compared the rates of intervention between those women who were attended by a private obstetrician and gave birth in a private hospital, those who were attended by a private obstetrician and gave birth in a public hospital, and those who had no private specialist care, were public patients giving birth in the public hospital.

The study population consisted of all women giving birth to a live baby in NSW from January 1 1996 to December 31 1997.

Methods

All the data were obtained from the NSW Midwives Data Collection (MDC), a population-based database with routinely collected data on all births in NSW in public and private hospitals and homebirths. The midwife who was present at the birth completes the form. All livebirths and stillbirths of at least 20 weeks gestation or 400 gms birthweight are included. Information is provided on demographic characteristics, pregnancy complications, labour and birth and infant characteristics.

Associations between patient/hospital group and maternal, infant and clinical factors were examined by contingency table analyses We examined obstetric intervention rates among medically 'low-risk' women classified into three patient/hospital groups:

1. private patients giving birth in private hospitals,
2. private patients giving birth in public hospitals and
3. all public patients.

To avoid cumbersome and lengthy statistical analysis we had a predefined population of medically 'low risk' women. Our criteria is similar to that of the Clinical Standards Advisory Group in the UK and described by Middle and MacFarlane in 1995 (MacFarlane 1995).

Medically low risk women

Women were described as 'low-risk' of poor pregnancy outcome if they were aged between 20 and 34 years with no medical or obstetric complications and a singleton cephalic-presenting infant of normal size (10th-90th birthweight percentile) born at term (37-41 completed weeks gestation).

The rates of interventions were then examined separately for women having a first baby (primiparous) and women having a second or subsequent baby (multiparous) women.

(One could very clearly argue that this definition of 'risk' is very 'reductive' and does not recognise all the other well known social constructs involved in the discourse around the term 'risk'. It is important to note here that this designation of 'risk' status was made only within the available data fields we had access to.)

The intervention cascade effect

See Figure 1 for the template of the pre-specified cascade effect of obstetric interventions as they occurred in labour and birth.

(Induction and augmentation were grouped together for simplicity because women described this procedure as having a drip 'to hurry things along' either before or during labour and the outcomes were similar.)

To establish that the interventions we were observing might be associated with other factors than clinical need it was important to draw a very stringent definition of 'low risk'. Consequently there were only 48% of both public and private women who were considered low risk with about 30% of these women being multiparous in each group.

The whole population consisted of 171,157 live births. We excluded the 356 recorded homebirths, and 95 births without public/private classification recorded. Of the remaining 170,706 women, 31% were private and 69% were public.

More detail on the profile of the population can be found in Table 1 in the reference study (Roberts et al 2000). Half of the women cared for by a private obstetrician gave birth in private hospitals - 58% of primiparous women and 55% of multiparous women. The women choosing a private obstetrician were less likely to have any medical or obstetric problems, they were older - especially in the over 35 year group, have fewer children (in the over four children group 1.8% versus 4.4% for public women) and have significantly larger babies that were born at full term. Private women had more twins and more babies not presenting head first, and their babies were likely to be heavier at birth.

Women who were considered to be medically 'low risk', had their first baby in a private hospital and had a private obstetrician were less likely to have a spontaneous onset of labour and more likely to have induction and/or augmentation. These women were less likely to have a vaginal birth and significantly more likely to have a forceps or vacuum birth, 34% for private women v 17% for women in the public hospital. They were twice as likely to have an epidural, 50% v 25% of women in the public system. Nearly half these low risk primiparous women who had a vaginal birth with a private obstetrician underwent an episiotomy (46.6%). This was twice the rate of those women who had a vaginal birth in public care (28.6%). The group in the middle were women who had a private obstetrician but gave birth in a public hospital. See Table 2 in the reference study (Roberts et al 2000).

Intervention rates for medically 'low risk' multiparous women were highest among women who gave birth in a private hospital with a private obstetrician and lowest in public women with intermediate rates for women with a private obstetrician in a public hospital. Amongst low risk multiparous women twice the number in the age group 30-34 years had a private obstetrician 61.9% v 35.6%. Many more multiparous women in the younger age group 20-24 years gave birth in the public system, 22.7% v 3.5%. This uneven distribution of ages even within the medically defined 'low risk' group meant that it was necessary to determine age-adjusted rates of intervention which we did in Tables 3 and 5 of the reference study. Again the medically 'low risk' multiparous women who gave birth in a private hospital with a private obstetrician were less likely to have spontaneous onset of labour, more likely to have induction and/or augmentation, less likely to have a vaginal birth and significantly more likely to have obstetric interventions at birth. They were also more likely to have an elective or an emergency caesarean section. These women were twice as likely to have an episiotomy for a vaginal birth 19.2% v 7.0% and three times more likely to have an epidural 31.3% v 9.2%. See Table 4 in the reference study.

Figures 2a and 2b are a diagrammatic representation of the cascade effect of obstetric interventions found in Tables 3. and 5. of the published paper (Roberts et al 2000) http://bmj.com/cgi/content/full/321/7254/137

Figure 2a The effect of a cascade of interventions in labour for 'low risk' primiparous women showing the added effect of private obstetric care in private hospital (Private/private), private obstetric care in public hospital (Public/private) and routine public hospital care (Public/public). Probabilities are based on age- standardised rates from the published study.

Source: Roberts C, Tracy S, Peat B. Rates for obstetric intervention among private and public patients in Australia: population based descriptive study. BMJ 2000; 321:137-41

Figure 2b. The effect of a cascade of interventions in labour for 'low risk' multiparous women showing the added effect of private obstetric care in private hospital (Private/private), private obstetric care in public hospital (Public/private) and routine public hospital care (Public/public). Probabilities are based on age-standardised rates from the published study.

Source: Roberts C, Tracy S, Peat B. Rates for obstetric intervention among private and public patients in Australia: population based descriptive study. BMJ 2000; 321:137-4

The study found there was an increasing level of intervention in the birth as interventions in labour (epidural, induction/augmentation) accumulated. This is demonstrated by an increasing gradient of intervention down the columns of each table for all patient/hospital groups.

However, there is also a gradient across the rows of the table with lower instrumental birth rates among public patients. This demonstrates how women cared for by a private obstetrician were more likely to begin interventions during labour and were also more likely to have operative intervention at the time of birth. These patterns of increased intervention at birth associated with intervention during labour were seen for both first time mothers and multiparas.

We found that among private women who had engaged a private obstetrician in a private hospital and had an epidural the most likely birth outcome was an instrumental birth with an episiotomy. Among similar women who gave birth in the public hospital system the most likely outcome was a non-instrumental vaginal birth without episiotomy.

Conclusions

Most midwives will be familiar with the inevitable cascade that happens once women are started on the intervention path. Our observation that epidurals begin a cascade of obstetric interventions leading to a poor chance of having a birth without any need for surgical intervention has been observed in the Cochrane Collaboration, Epidural versus non- epidural for pain relief in labour (Howell 1999). Our study doesn't have details on birth outcomes, such as duration of labour, nor the reasons for intervention, but its strength lies in the size and validity of the population database used. It can't demonstrate cause and effect although a lot of these relationships have been examined in randomised controlled trials. We also can't generalise our results to other populations who don't have the same sort of maternity system.

The most important reason for doing this research was to make this information available to women so that when they choose their obstetric care based on a perceived access to pain relief they might be completely aware of all the possible implications and consequences of that choice. Hopefully this information will be useful for women and their doctors and midwives to be better informed of the possible consequences of such a choice and the chances of a "normal" birth.

References

1. AIHW (2000) Australia's Health. www.aihw.gov.au/publications/health/ah00/index.html

2. Brown S. Lumley J. (1994) Satisfaction with care in labor and birth: a survey of 790 Australian women. Birth: Issues in Perinatal Care & Education, 21(1):4-13

3. Cary A. (1990) Intervention rates in spontaneous term labour in low risk nulliparous women. Aust & NZ J Obstet and Gynaecol 30: 46-51

4. Commonwealth of Australia (1999) Senate Community Affairs References Committee. Rocking the Cradle: A Report into Childbirth Procedures Canberra. Commonwealth of Australia 1999- 8 December 1999 www.aph.gov.au/senate/committee/history/index.htm#Community

5. Editorial, BMJ, 2000,321(7254) by Professor James King bmj.com/cgi/content/abstract/321/7254/137

6. Howell CJ. Epidural versus non-epidural analgesia for pain relief in labour (Cochrane review). In: The Cochrane Library, Issue 3, 1999. Oxford: Update Software.

7. Middle C, MacFarlane A (1995) Labour and delivery of 'normal' primiparous women: analysis of routinely collected data. British J of Obstetrics and Gynaecology 102:970-977

8. Roberts CL, Tracy S, Peat B. Rates for obstetric intervention among private and public patients in Australia: population based descriptive study. BMJ 2000; 321(7254): 137-141. bmj.com/cgi/content/full/321/7254/137

9. Shorten A, Shorten B (1999) Episiotomy in NSW hospitals 1993-1996: Towards understanding variations between public and private hospitals Australian Health Review. 22(1): 19-32.