How We Do It

The evolution and future of human reproduction

Deliver Unto Caesar: A Surgical Epidemic

Where will runaway rates of Caesarian section lead us?

Veterinarians Katy Evans and Vicki Adams recently reported that birth by Caesarean section is now common for pedigree dogs. Indeed, it is almost obligatory for wide-headed breeds, with rates of 81% for French bulldogs, 86% for British bulldogs and a stunning 92% for Boston terriers. Tending in the same direction, rates of C-section for human births are escalating worldwide, now exceeding 70% in extreme cases. Understandably, when complications occur, babies are routinely delivered by C-section if facilities are available. But many women now choose Caesareans for personal reasons.

Rising Rates of Caesareans in the USA

Caesarean birth rates have steadily risen in the USA, from less than 5% in 1965 to around 20% in 1996 and over 30% by 2006. The rise continues, with around one-and-a-half million Caesarean births in the USA last year. C-section is now the commonest surgical procedure in US hospitals. But major regional differences in frequency exist. With almost 40%, Lousiana is currently the Caesarean champion of the USA, followed closely by New Jersey and Florida.

The high frequency of C-sections in the USA reflects changes in medical practice rather than any shift in real risks. Some might see this as a triumph of medical technology, offering mothers the option of avoiding the pain of vaginal birth, but the implications are serious. A 1985 report by the World Health Organization noted that countries with some of the lowest perinatal mortality rates in the world had C-section rates below 10%. WHO concluded that there is no justification for any region to have a rate exceeding 10-15%, and two recent studies have shown that a rise in frequency of C-sections above 15% has adverse health consequences.

Rates Rising Worldwide

The Ceasarean epidemic is by no means confined to the USA; rates are climbing rapidly worldwide. On average, every fourth European baby is now delivered by C-section. This is the rate in the UK, already double the 1990 level. Rates are somewhat higher in Germany and Portugal and nearing 40% in Italy. Only the Netherlands, where health policy emphasizes natural birth, is just below WHO’s upper limit of 15%. Beyond Europe, the C-section rate is close to 30% in Australia, around 35% in South Korea and over 45% in China.

It might be thought that high rates of C-section occur only in wealthy industrialized countries, but that is not so. Data from a WHO global survey of nine Asian countries revealed an overall average of 27%. Both Thailand and Vietnam outpaced the USA with rates close to 35%. In Asia, propitious birthdays are a special factor driving higher rates of elective C-section. More recently, a surprisingly high rate of Caesarean births was reported for a university hospital in Dar es Salaam, Tanzania, rising from 19% to 49% between 2000 and 2011. Over the same period, maternal mortality increased significantly from 4.6 to 6.5 per thousand live births. Yet C-section rates over 70% in some private clinics in South Africa eclipse the latest level recorded for that Tanzanian hospital.

Risks of C-Sections

Increased use of Caesarean section without medical necessity might be defensible if the procedure were risk-free. But major surgery under anesthesia increases mortality risks for both mother and child, so this should be an intervention of last resort. Rates of maternal infection following Caesarean surgery are high, reaching almost 10% in one study. Infection may spread to the womb, possibly causing scars reducing a woman’s future chances of conception. A prospective study in Norway, published in 2004, revealed that 21% of women had at least one complication after C-section, the most frequent being blood loss, often requiring transfusion.

There are also more subtle side-effects. For instance, babies born by C-section have an aberrant population of gut bacteria. Insidiously, infection diminishes a mother’s ability to care for her baby. Postpartum depression is also more likely following Caesarean birth. A study using functional MRI about three weeks after delivery showed that brains of mothers who gave birth naturally were significantly more responsive to their own baby’s cries than those of mothers who underwent C-section. Quite generally, any surgical intervention disrupts the natural mechanism of childbirth and obstructs the normal process of mother-infant bonding.

Why the Upward Trend?

But why have C-sections become so common? Firstly, since 1998 it has been common to stick with Caesareans once a mother has had one baby born this way: “Once a Caesarean, always a Caesarean”. Yet the 1985 WHO report explicitly concluded that there is no evidence that successive C-sections are essential. The rate of C-section in the US also increases with age, from roughly a quarter of births for mothers less than 20 years old to about half for those aged 40-50. In addition, most breech babies born in America are now delivered by C-section, although manipulation (version) was used to correct the baby’s position for vaginal birth until the 1950s in the USA, as is still the case in several other countries. Another factor is that one in ten expectant mothers suffer from fear of childbirth (tokophobia). In combination, these factors have all contributed to the worldwide rise in Caesarean births.

So should we be concerned about ending up like pedigree dogs? Not yet, but it should not be forgotten that our bodies are products of a long evolutionary history  —  and the bearers, one hopes, of a long evolutionary future. By proliferating unnecessary C-sections we may be embarking on a trajectory that will inexorably lead to increased problems with natural birth. C-sections will become obligatory, not optional.

 

References

Azad, M.B., Konya, T., Maughan, H., Guttman, D.S., Field, C.J., Chari, R.S., Sears, M.R., Becker, A.B., Scott, J.A. & Kozyrskyj, A.L. (2013) Gut microbiota of healthy Canadian infants: profiles by mode of delivery and infant diet at 4 months. Canad. Med. Ass. J. 185:385-394.

Belizán, J.M., Cafferata, M.L., Althabe, F. & Buekens, P. (2006) Risks of patient choice cesarean. Birth 33:167-169.

Evans, K.M. & Adams, V.J. (2010) Proportion of litters of purebred dogs born by caesarean section. J. Small Anim. Pract. 51:113-118.

Gibbons, L., Belizán, J.M., Lauer, J.A., Betrán, A.P., Merialdi, M. & Althabe, F. (2010) The Global Numbers and Costs of Additionally Needed and Unnecessary Caesarean Sections Performed per Year: Overuse as a Barrier to Universal Coverage (Background Paper 30). Geneva, Switzerland: WHO Press.

Häger, R.M., Daltveit, A.K., Hofoss, D., Nilsen, S.T., Kolaas, T., Oian, P. & Henriksen, T. (2004) Complications of cesarean deliveries: rates and risk factors. Am. J. Obstet. Gynecol. 190:428-434.

Litorp, H., Kidanto, H.L., Nystrom, L., Darj, E. & Essén, B. (2013) Increasing caesarean section rates among low-risk groups: a panel study classifying deliveries according to Robson at a university hospital in Tanzania. BMC Pregn. Childb. 13:107:1-10.

MacDorman, M.F., Menacker, F. & Declercq, E. (2008) Cesarean birth in the United States: Epidemiology, trends, and outcomes. Clin. Perinatol. 35:293-307

Swain, J.E., Tasgin, E., Mayes, L.C., Feldman, R., Constable, R.T. & Leckman, J.F. (2008) Cesarean delivery affects maternal brain responses to own baby cry. J. Child Psychol. Psychiatr. 49:1042-1052.

Wloch, C., Lamagni, T., Harrington, P., Charlett, A. & Sheridan, E. (2012). Risk factors for surgical site infection following caesarean section in England: results from a multicentre cohort study. BJOG Int. J. Obstet. Gynaecol. 119:1324-1333.

World Health Organisation (1985) Appropriate technology for birth. Lancet 326:436-437.

 

An on-stage interview for the Chicago Humanities Festival in October 2013 exploring my book How We Do It (subsequently included in NPR's "Best Reads for 2013") has been posted on YouTube, notching up almost 5000 hits to date:

https://www.youtube.com/watch?v=-of-AmezPXk&list=UUM2nSBiVH_QQkaHfOmwkdtQ&index=26

 

Robert Martin, Ph.D., is the A. Watson Armour III Curator of Biological Anthropology at the Field Museum in Chicago.

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