Short- and Long-term Outcomes after Cesarean Section

Rosalie M Grivell; Jodie M Dodd

Disclosures

Expert Rev of Obstet Gynecol. 2011;6(2):205-215. 

In This Article

Factors Contributing to the Increased Rate of Cesarean Birth

A number of reasons have been proposed for the observed increase in cesarean birth. Proposed contributing factors include advanced maternal age, particularly with first birth, multiple pregnancy, breech presentation, suspected low infant birthweight, private hospital status[7] and increasing maternal BMI.[8]

Other contributing factors include organizational factors, women's choices regarding childbirth and preferences for care, in addition to obstetrician's characteristics and care practices.[9] The contribution of each of these factors is complex, and many are inter-related. While much of this discussion is outside the scope of this articles's topic, we have attempted to summarize the key contributors.

A woman's risk of CS does not seem to differ by type of primary carer. The Cochrane systematic review concluded that there was no difference in the risk of CS if the midwife was the primary caregiver compared with another professional.[10]

In Australia in 2007, two thirds of all twins were born by CS,[1] compared with 47% in 1998.[7] Over this same time period, there was an increasing proportion of multiple births.[1] Similarly, singleton term breech infants were also more likely to be delivered by CS, the proportion increasing from 81% in 1998 to 96% in 2007.[1,7] Australian national birth data collection consistently report a difference in CS rates between public and private hospitals.[1] In 2007, the national CS rate in Australia was 31.8%. However, women with private health insurance experienced a rate of 41.5% compared with women who birthed in public hospitals, with a cesarean rate of 27.8%.[1]

Being overweight or obese during pregnancy is increasingly common, with an estimated 35% of Australian pregnant women having a BMI over 25 kg/m2.[11] We recently reported that 50% of pregnant women in South Australia are overweight or obese.[12] Being overweight or obese is a significant risk factor for a number of adverse health outcomes. For women with a BMI over 25 kg/m2, the risk of both emergency and elective cesarean birth is increased, the risk increasing with increasing BMI.[12] The risk of cesarean birth has been estimated to increase by 7% for every one unit increase in maternal BMI,[13] with up to one in seven procedures directly attributable to obesity.[14]

Smith et al. examined the effect of increasing maternal age in 1.5 million births in Scotland, UK, over a 25-year period, from 1980.[15] For every 5-year increase in maternal age at the time of birth, the risk of CS increased by 50%, with 38% of the additional surgical procedures being attributable to increasing maternal age.[15]

Increased use of interventions in pregnancy and childbirth, such as intrapartum fetal heart rate monitoring and induction of labor (IOL), may also play a role in the rising CS rate. The Cochrane systematic review by Alfirevic et al. evaluated the use of continuous cardiotocography in labor and subsequent birth outcomes.[16] When compared with intermittent auscultation, continuous cardiotocography in labor did not reduce perinatal death or cerebral palsy, but increased the chance of women undergoing both cesarean (relative risk [RR]: 1.66; 95% CI: 1.30–2.13) and instrumental birth (RR: 1.16; 95% CI: 1.01–1.32).[16]

The proportion of women experiencing IOL has increased over the past several decades,[17,18] and while there are well-recognized maternal and obstetric indications for IOL, over half of induction procedures are performed for reasons other than recognized indications.[17,18] It has been reported that the liberal use of IOL at term in an otherwise uncomplicated pregnancy is a significant contributor to rising CS rates, in addition to increasing a woman's risk of a number of other adverse birth outcomes.[19,20] Grivell and colleagues evaluated the association between labor onset and the risk of emergency CS for women with a singleton pregnancy at term, in a prospective cohort study.[21] In a population of over 28,000 women, IOL for other than recognized medical or obstetric indications was associated with a 67% increased risk of emergency CS when compared with the spontaneous onset of labor.[21] This finding is consistent with that of other observational studies, where IOL at term in women with an otherwise uncomplicated pregnancy increases the risk of a cesarean birth by two- to threefold, even after adjusting for parity.[19,20,22]

Variations in intrapartum management, particularly in relation to management of labor arrest, may also play a role in increasing CS rates, with reports suggesting a high proportion of intrapartum procedures being performed early in labor before the active phase of labor has been reached, or without the use of oxytocin.[9]

With more women experiencing CS at the time of their first birth, there is a large proportion of women with a second or subsequent pregnancy occurring after previous cesarean. This, in the context of decreasing rates of attempted vaginal birth after cesarean (VBAC), further contributed to an increase in CS rates.[23]

Some propose that the risks to the fetus associated with vaginal birth may be less acceptable to women and their caregivers, with cesarean birth perceived as an increasingly safe and acceptable alternative mode of birth. Walker and colleagues asked women in late pregnancy, and their caregivers, the level of additional fetal risk considered acceptable to avoid CS and achieve a vaginal birth.[24] The median level of acceptable risk for both women and staff was low, at 10 out of 1000 for women and 13 out of 1000 for staff.[24] These findings highlight the high expectations held by women, obstetricians and midwives for favorable pregnancy outcomes, an issue which may contribute to the increasing CS rate. With increasing rates of elective CS in the absence of medical indications,[25] a prospective RCT of vaginal birth compared with CS of considerable size would be required to evaluate the risks of maternal and infant morbidity associated with each mode of birth. However, it is unlikely that such a trial would be feasible, with low willingness of women and their caregivers to participate, as reported in a recent Australian survey.[26]

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