Attributable factors for the rising cesarean delivery rate over 3 decades: an observational cohort study.

BACKGROUND: Cesarean delivery rates continue to rise globally, the reasons for which are incompletely understood. OBJECTIVE: We aimed to characterize the attributable factors for the increasing cesarean delivery rates over a 30-year period within our health network. STUDY DESIGN: This was a planned observational cohort study across 2 hospitals (a large tertiary referral hospital and a metropolitan hospital) in Sydney, Australia using data from a previously published study. The following 2 time periods were compared: 1989-99 and 2009-16, between which the cesarean delivery rate increased from 19% to 30%. The participants were all women who had a cesarean delivery after 24 weeks' gestational age. The data were analyzed using multiple imputation and robust Poisson regression to calculate the differences in the adjusted and unadjusted relative risk of cesarean delivery and estimate the changes in the cesarean delivery rate attributable to maternal and clinical factors. The primary outcome was cesarean delivery. RESULTS: After 576 exclusions, 102,589 births were included in the analysis. Fifty-six percent of the increase in the rate of cesarean delivery was attributed to changes in the distribution of the maternal age, body mass index, and parity and to a history of previous cesarean delivery. An additional 10% of the increase was attributed to changes in the obstetrical management of the following high-risk pregnancies: multiple gestation, malpresentation (mainly breech), and preterm singleton birth. When prelabor cesarean deliveries for maternal choice, suspected fetal compromise, previous pregnancy issues, and suspected large fetus were excluded, 78% of the increase was attributed to either maternal factors or changes in the obstetrical management of these high-risk pregnancies. CONCLUSION: Most of the steep rise in the cesarean delivery rate from 19% to 30% was attributed to changes in the maternal demographic and clinical factors. This observation is relevant to developing preventative strategies that account for nulliparity, age, body mass index, and management of high-risk pregnancies.

Sexually transmitted infections and preterm birth among Indigenous women of the Northern Territory, Australia: A case-control study.

BACKGROUND: The incidence of both sexually transmitted infection (STI) and preterm birth is high among Indigenous women in the Northern Territory, Australia. It was hypothesised that these factors are linked. AIMS: To analyse whether antenatal STI is associated with preterm birth among Northern Territory Indigenous women. MATERIALS AND METHODS: A retrospective case-control study was conducted at a tertiary maternity hospital in the Northern Territory. Rates of STI among pregnant Indigenous women were compared between cases (singleton births at <37 weeks gestation) and controls (singleton births at 37 or greater weeks gestation). The association between the composite of any STI (chlamydia, gonorrhoea, trichomonas or syphilis) and preterm birth was evaluated by logistic regression analysis, adjusting for confounders. Secondary endpoints were the associations between each of these infections and preterm birth. RESULTS: There were 380 cases and 380 controls. Diagnosis of any sexually transmitted infection (composite) in pregnancy was not associated with preterm birth (adjusted odds ratio (aOR) 0.9, 95%CI 0.58-1.39). Women were at increased risk of preterm birth if they had gonorrhoea in pregnancy (aOR 2.92, 95%CI 1.07-7.97); there was no association with chlamydia (aOR 1.38, 95%CI 0.63-3.04) or trichomonas (aOR 0.66, 95%CI 0.39-1.12). There were three syphilis diagnoses among controls and none among cases. CONCLUSIONS: Sexually transmitted infection (considered overall) in pregnancy did not affect preterm birth risk among Northern Territory Indigenous women. An association with preterm birth was observed for gonorrhoea in pregnancy but not with chlamydia, trichomonas or syphilis.