Factors influencing Caesarean Rates

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CHAPTER 2. BACKGROUND AND LITERATURE REVIEW

Pregnancy, Labour and Birth

The human gestation period is thirty eight weeks, but pregnancy is typically calculated from the last menstrual period and so is commonly regarded as having a duration of forty weeks. During this time, the cluster of cells formed after fertilisation will, on average, develop into a 55 centimetre long, 3.5 kilogram baby that somehow has to find its way into the world (Kitzinger, 1997). Globally 133-135 million births are predicted to occur annually for the next 25 years (United States (U.S.) Department of Commerce, 1996). In New Zealand (NZ) in 2003, 54,581 women gave birth to 55,289 babies (NZ Health Information Service [NZHIS], 2006). Two thirds of these women (67.4%) gave birth by „normal vaginal delivery‟.
Vaginal delivery typically includes three stages of labour: the first stage of labour involves a period of regular contractions that accomplish the effacement (dilation) of the cervix to 10 centimetres which is sufficient for the passage of the foetal head; the second stage begins when the cervix is fully effaced and ends when the baby is born; the third stage begins after the baby is born and ends when the placenta and foetal membranes are expelled (Cunningham et al., 2005). Of women giving birth in NZ in 2003, 9.5% experienced operative vaginal births, which is a “vaginal birth that includes assistance using operative procedures” (NZHIS, 2006, p. 107), such as the use of forceps or vacuum (vontouse) extraction. The focus of this study was on caesarean section, which can occur either before or after the commencement of labour. In NZ in 2003 almost a quarter of birthing women (23.1%) gave birth by caesarean section (NZHIS, 2006).

Definition, history and procedure.

The Williams Obstetrics Guide defines caesarean delivery as “the birth of a foetus through incisions in the abdominal wall (laparotomy) and the uterine wall (hysterotomy)” (Cunningham et al., 2005, p. 588). The origin of the procedure is debatable, although it is popularly suggested that the name arises from the abdominal surgical delivery of Julius Caesar. This view has generally been discounted as it is recorded that his mother was still alive during his lifetime, and at that time the procedure was unfailingly fatal to the mother (Cunningham et al., 2005; Lawrence, 1997; Lurie, 2005).
Although there is considerable dispute within the literature, one of the first documented successful caesarean sections, resulting in a live mother as well as baby, was performed in Ireland in 1738 (Helen Churchill, 1995). Prior to this, the operation was typically conducted to save the life of the infant when it had been determined that the mother’s life could not be saved (Lawrence, 1997). Within the Christian world this was encouraged by the added incentive of extracting the baby for baptism in order to ensure its soul would be saved (Frazer, 1987). It was not until the twentieth century that caesarean deliveries consistently had positive outcomes for both mother and child. Maternal outcomes following the surgery have continued to improve with advances in anaesthesia (such as chloroform), sterilisation techniques that reduced infections, and changes to surgical techniques such as suturing (Cunningham et al., 2005).
Modern mortality rates associated with caesarean delivery are low, and although perhaps higher than mortality rates for vaginal delivery, depending on whether conducted under emergency or elective conditions, the absolute risk is low (Lang & King, 2008). Despite these low mortality rates, research reports higher risks of other complications with caesarean deliveries compared with vaginal delivery (Cunningham et al., 2005). For example, maternal morbidity research has found the risk of endometritis (infection) up to 21 times higher following a caesarean delivery when compared to a vaginal delivery, with even higher risk when the caesarean follows a trial of labour (Burrows, Meyn, & Weber, 2004).
Modern day caesarean sections are performed after a regional or general anaesthesia has been administered and a catheter has been inserted (Kitzinger, 1997). Two types of regional anaesthesia are typically used: a spinal block is “the introduction of a local anaesthetic into the subarachnoid space” (Cunningham et al., 2005, p. 480), also used frequently during operative vaginal deliveries; or epidural analgesia which is achieved “by injecting a local anaesthetic into the epidural or peridural space” (Cunningham et al., 2005, p. 483). This form of anaesthetic is also commonly used during vaginal births for pain relief. The term „epidural‟ is frequently used as an umbrella term to refer to all regional anaesthetics, including lumbar, spinal and epidural anaesthetics (NZHIS, 2006). These regional anaesthesias numb the patient while allowing her to remain awake during the delivery, as compared to general anaesthetic where the patient is rendered unconscious.
General anaesthetic is the most expedient to administer and involves the intravenous administration of an analgesia, inserting a breathing tube via the oesophagus (intubation), and administering a gas anaesthetic to keep the patient unconscious (Cunningham et al., 2005). Due to its rapid effect a general anaesthetic is most commonly used in urgent cases, but is usually the least preferred option from the patient’s perspective, as the mother is unconscious when the baby is born (Kitzinger, 1997). Furthermore, the American College of Obstetricians and Gynecologists (ACOG) has recommended that, unless contraindicated, regional anaesthesia is preferable to general anaesthesic due to the higher risks associated with general anaesthesia (ACOG, 2004).
A review of the research into the effects of anaesthesia reveals relatively consistent findings, with general anaesthesia associated with more negative outcomes following caesarean delivery than epidural anaesthesia, regarding both physical and emotional reactions to the birth (Clement, 2001;
Fisher, Stanley, & Burrows, 1990; Garel, Lelong, & Kaminski, 1987; Reichert, Baron, & Fawcett, 1993). However, research has been mixed regarding emotional detachment between mother and infant following caesarean delivery, with Herishanu-Gilutz, Shahar, Schattner, Kofman, & Holcberg (2009) finding emotional detachment following emergency caesarean, particularly after general anaesthetic, while Figueiredo, Costa, Pacheco, & Pais (2009) found no association between emotional detachment and any anaesthesia, epidural or general.
Caesarean deliveries are typically performed via a horizontal incision low on the abdomen (commonly referred to as the „bikini line‟), as this leads to less risk of the scar reopening during subsequent pregnancies than the historically preferred vertical incision (Cunningham et al., 2005). The incision is made through the abdominal wall to reveal the lower uterine segment, and then through this to reach the bag of amniotic fluid which is then pierced. The baby is then manoeuvred through this opening, often with some pressure on the upper side of the uterus to encourage the baby through the opening, and an injection may be given to encourage the placenta to detach from the uterine wall so it can also be removed through the abdomen (Kitzinger, 1997). Caesareans are typically completed in less than fifteen minutes, while the procedure of stitching the layers of the uterus and abdominal wall afterwards may take up to an hour (Kitzinger, 1997).
Until the mid 1970s, fathers were excluded from the operating theatre during caesarean births. At that time caesareans were treated solely as surgical procedures and it was viewed as unsafe, for hygiene and practical reasons, to have the fathers attend (Cohen, 1977; DiMatteo et al., 1996; Hedahl, 1980). Fathers now attend the majority of caesarean births, but are still excluded from the surgery if general anaesthesia is used (Kitzinger, 1997).

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Prevalence Rates.

As noted previously, in 2003 in NZ 55,289 babies were born, and of these 23.1% were born via caesarean section (NZHIS, 2006). NZ‟s rate of caesarean deliveries has steadily increased over the last two decades, with the current figure in sharp contrast to the 11.7% reported in 1988 (NZHIS, 2004). This increase reflects an international trend, with most countries now having a caesarean rate well over the 10-15% still recommended by the World Health Organisation (WHO, 1985).
Published caesarean rates for a number of countries are presented in Table 1 which shows the trend of rising rates for the United Kingdom (UK), United States (US), Australia and NZ.  Within NZ the highest rates are reported in the most populous areas.
The WHO recommended caesarean rate was published following a finding that perinatal mortality rates did not necessarily improve with increasing caesarean rates (WHO, 1985). The 9 difference between this recommendation and current actual rates is clear, but the reasons behind this difference are not immediately evident. There remains contention regarding the ideal rate of caesarean deliveries, with a number of articles, letters and commentaries continuing to debate this issue (Anonymous, 1997; Ash, 1997; Groom & Brown, 2000; Matthews et al., 2003; O’Connell & Lindow, 2000; Resnik, 2006; Sachs, Kobelin, Castro, & Frigoletto, 1999).
There are numerous reasons for caesarean delivery, with some more common than others. Currently in the US 85% of caesareans are performed due to previous caesarean, dystocia, foetal distress, or breech presentation (Cunningham et al., 2005). Dystocia is a heterogeneous term that includes most elements of ineffective labour including cases when the foetus is too big or the pelvis too small (cephalopelvic disproportion), the foetus is in an awkward position, or where there is failure to progress (i.e., a lack of cervical dilation or baby not descending) (Cunningham et al., 2005). In 2003 in Western Australia the most common reasons recorded for caesarean sections included: “previous caesarean section or other uterine surgery (26.7%); foetal distress (11.4%); placental disorders and/or haemorrhage (11.0%); obstruction or delayed labour (9.9%); breech and other malpresentation (9.2%); and cephalopelvic disproportion (7.3%)” (Health Department of Western Australia (HDWA), 2004, p. 21)

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Factors Influencing Caesarean Rates.

The increase in caesarean rates over recent decades cannot be fully explained by any single factor. Instead, there are multiple factors contributing to the burgeoning number of surgical deliveries, including the finding that caesarean rates rise with maternal age, and the average maternal age is rising (Cunningham et al., 2005). The average age of mothers giving birth in NZ in 2003 was 30.2 years, with nearly one third of mothers aged between 30-34 years (NZHIS, 2006). This represents the continuation of a two-decade trend of increasing maternal age (NZHIS, 2004). As can be seen in Table 2, in NZ in 2003, 35.8% of women over the age of forty had a caesarean delivery, compared with only 15.3% of women aged between 20-24 (NZHIS, 2006).  The association between rising maternal age and caesarean section rates can also be seen in data from the US.  Women aged under twenty who gave birth in the US in 2003 had a caesarean rate of 19.1% compared to: 26.4% for women aged between 25-29; 36.8% for women aged between 35-39; and 42.5% for women giving birth who were aged over forty years old (Martin et al., 2005).
Induction of labour is also associated with increased rates of caesarean delivery (Cunningham et al., 2005). Induction of labour can be defined as “an intervention undertaken to stimulate the onset of labour by pharmacological or other means” (NZHIS, 2006, p. 106). Induction of labour may be initiated by pharmacological means (e.g., Prostaglandin or Oxytocin) or mechanical/surgical techniques such as artificially rupturing the membranes (Government Statistical Service for the Department of Health [GSSDH], 2005). The frequency of induction is increasing, with the numbers in the US almost doubling from 20% in 1989 to 38% in 2002 (Cunningham et al., 2005). In NZ in 2003, 19.7% of labours were induced (NZHIS, 2006).

Chapter 1. Overview and Rationale 
The Researcher’s Perspective
Rationale
Thesis Organisation
Chapter 2. Background and Literature Review 
Pregnancy, Labour and Birth
Caesarean Section
Definition, history and procedure
Prevalence Rates
Factors influencing Caesarean Rates
Caesarean Classification (Emergency or Elective)
Impact of Caesarean Section
Medical Outcomes
Repeat Caesareans
Psychological outcomes
Reactions to Caesarean
Mother-Infant Relationship
Breastfeeding
Chapter 3. Method 
Participants
Measures
Semi-structured Interview
Demographic and Medical Questionnaire
Procedure
Data analysis
Chapter 4. Results 
The Experience of Pregnancy
Preferences and Expectations during pregnancy
Unplanned Caesareans
Planned Caesareans
Summary
Chapter 5. Discussion 
Clinical Implications of Findings
Strengths and Limitations of the Research
Implications for Future Research
Conclusion
References
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