Saturday, January 31, 2009

Cesarean complications rise in line with changes in mothers

A number of studies have been published recently, which, if read in the context and knowledge of other applicable studies, would inform women more accurately than many media reports have managed to do.

Take for example this week's highly publicized U.S. report, 'Severe Obstetric Morbidity in the United States: 1998-2005', by EV Kuklina et al. They found that the "prevalence of delivery hospitalizations (per 1,000) complicated by at least one severe obstetric complication increased from 0.64% (n=48,645) in 1998-1999 to 0.81% (n=68,433) in 2004-2005." And that

Perception of risk - actual increase versus percentage increase
Clearly, these numbers in real terms - especially when you consider that they take into account ALL delivery complications (including emergency cesareans) - are relatively small (less than 1%), but what many media reports concentrated on was the '% increase' number, which of course looks a lot higher - and riskier - when reported without the 'per 1000' figures.

For example, renal failure increased "by 21% (from 0.23 to 0.28), pulmonary embolism by 52% (0.12 to 0.18), adult respiratory distress syndrome by 26% (0.36 to 0.45), shock by 24% (0.15 to 0.19), blood transfusion by 92% (2.38 to 4.58), and ventilation by 21 % (0.47 to 0.57).

The authors conclude that: "Rates of severe obstetric complications increased from 1998-1999 to 2004-2005. For many of these complications, these increases were associated with the increasing rate of cesarean delivery.

But is cesarean surgery the reason for greater severe morbidity - or are other factors to blame?
Adding to a growing body of evidence on this subject, a Scottish review this month by A Poobalan et al, 'Obesity as an independent risk factor for elective and emergency caesarean delivery in nulliparous women - systematic review and meta-analysis of cohort studies' tells us that cesarean delivery "risk is increased by 50% in overweight women and is more than double for obese women compared with women with normal BMI."

And in 2003, KS Joseph et al's Canadian study, 'Changes in maternal characteristics and obstetric practice and recent increases in primary cesarean delivery', which set out to "estimate the contribution of changes in maternal characteristics (namely, age, parity, prepregnancy weight, weight gain in pregnancy, smoking status) and obstetric practice (namely, labor induction, epidural anesthesia, delivery by an obstetrician, midpelvic forceps delivery) to recent increases in primary cesarean delivery rates", concluded that "Recent increases in primary cesarean delivery rates are a consequence of changes in maternal characteristics. Obstetric practice, which has altered due to changes in maternal characteristics and concerns related to fetal and maternal safety, has also contributed to increases in primary cesarean delivery."

Specifically, the researchers noted a 14% increase in cesarean deliveries for dystocia, 24% for breech, 21% for suspected fetal distress, 47% for hypertension, and 73% for miscellaneous indications between 1988 and 2000. Importantly: "Adjustment for maternal characteristics reduced the temporal increase" in cesarean rates from 21% to 2% [and] Additional adjustment for obstetric practice factors further reduced period effects."

The future of cesarean rates
A review by Rebecca Simmons, MD., 'Perinatal Programming of Obesity', published in the U.S. in October 2008, reminds us that the prevalence of obesity "has risen dramatically over the last decade [and a] number of epidemiological studies have shown that there is a direct relationship between birth weight and BMI in childhood and in adult life." I would suggest that with no sign of a decline in obesity rates (in fact, quite the opposite) and with women continuing to have their babies later and later in life, we are not going to see any significant reduction in primary cesarean rates at all, and we need to be very careful about implementing strategies to drastically reduce them since this will result in greater morbidity and mortality for these women and their babies.

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