Obstacles to reducing cesarean rates in a low-cesarean setting: the effect of maternal age, height, and weight

OBJECTIVE: To examine risk factors for elective and nonelective cesarean delivery in a population with a low cesarean rate. METHODS: Nulliparous women delivering singleton births in Sweden during 1992-93 were included (n=92,623). Logistic regression analyses were performed to calculate adjusted odds ratios (ORs) and rates of cesarean delivery. RESULTS: The overall cesarean rate was 11.9%. Risks for cesarean increased consistently with increasing maternal age, decreasing maternal height, and increasing prepregnancy body mass index (BMI). Compared with teenagers, the OR of cesarean was 2.6 among women 30-34 years and 4.4 among women 35 years of age or older. Compared with tall women (greater than 174 cm), the OR of cesarean for women 155-164 cm was 2.0, and 4.5 for short women (less than 155 cm). Compared with lean women (BMI less than 20.0), the ORs of cesarean for overweight (BMI 25.0-29.9) and obese women (BMI of at least 30.0) were 1.8 and 2.4, respectively. Similar risks also were obtained when the analyses were restricted to elective or nonelective cesarean deliveries. The effect of prepregnancy BMI on cesarean rate was influenced by maternal height: among tall women, rates of cesarean increased from 5% among lean women to 11% among obese women, whereas corresponding rates among short women were 19% and 36%, respectively. The influence of mother's education, type of hospital, and other factors was considerably less. CONCLUSION: The increase in maternal age at first birth and the weight among young women present obstacles to the reduction of cesarean rates in developed countries.