Preventable obstetrical interventions: how many caesarean sections can be prevented in Canada?

Public health authorities have been alarmed by the progressive rise in rates of Caesarean section in Canada, approaching one birth in three in several provinces. We aimed therefore to consider what were preventable obstetrical interventions in women with a low-risk pregnancy and to propose an analytic framework for the reduction of the rate of CS. We obtained statistical variations of CS rates over time, across regions, and within professional practices from MED-ÉCHO, the Quebec hospitalization database, from 1969 to 2009. Data were extracted from a recent systematic review of the cascade of obstetrical interventions to calculate the population-attributable fractions for each intervention associated with an increased probability of CS. We thereby identified expectant management (as an alternative to labour induction) and planned vaginal birth after CS as the leading strategies for potentially reducing rates of CS in women at low risk. For vaginal birth after CS, an increase to its 1995 level could lower the current CS rate of 23.2% (2009 to 2010) to 21.0%. Other alternatives to obstetrical interventions with a potential for lowering CS rates included non-pharmacological pain control methods (such as continuous support during childbirth) in addition to usual care, intermittent auscultation of the fetal heart (instead of electronic fetal monitoring), and multidisciplinary internal quality assessment audits. We believe, therefore, that the concept of preventable CS is supported by empirical evidence, and we identified realistic strategies to maintain a CS rate in Quebec near 20%.

Les autorités en matière de santé publique ont été alarmées par la hausse graduelle des taux de césarienne (CS) au Canada (près d'une naissance sur trois dans plusieurs provinces). Nous avons donc cherché à identifier les interventions obstétricales qui pouvaient être évitées chez les femmes qui connaissent une grossesse les exposant à de faibles risques, ainsi qu'à proposer un cadre analytique pour la réduction du taux de CS. Les variations statistiques, entre 1969 et 2009, des taux de CS avec le temps, d'une région à l'autre et en fonction des pratiques professionnelles ont été tirées de MED-ÉCHO (la base de données sur l'hospitalisation au Québec). Des données ont été tirées d'une récente analyse systématique de la cascade d'interventions obstétricales en vue de calculer les fractions étiologiques du risque pour chacune des interventions associées à une probabilité accrue de CS. Nous avons ainsi identifié la prise en charge non interventionniste (à titre de solution de rechange au déclenchement du travail) et l'accouchement vaginal planifié après CS comme étant les principales stratégies pouvant permettre la réduction des taux de CS chez les femmes exposées à de faibles risques. Pour ce qui est de l'accouchement vaginal après CS, une hausse jusqu'à son niveau de 1995 pourrait faire passer le taux actuel de CS de 23,2 % (de 2009 à 2010) à 21,0 %. Parmi les solutions de rechange aux interventions obstétricales qui présentent le potentiel d'abaisser les taux de CS, on trouvait les méthodes non pharmacologiques de maîtrise de la douleur (comme l'offre d'un soutien continu pendant l'accouchement) s'ajoutant aux soins habituels, l'auscultation intermittente du cœur fœtal (plutôt que le monitorage électronique du fœtus) et les audits internes multidisciplinaires de la qualité. Nous estimons donc que le concept de la CS évitable est soutenu par des données empiriques et nous avons identifié des stratégies réalistes permettant d'assurer le maintien, au Québec, d'un taux de CS se situant près de 20 %.

Nickel remediation by AM-colonized sunflower.

This greenhouse study aimed to examine the contribution of arbuscular mycorrhizal (AM) colonization on the uptake of and tolerance to nickel (Ni) in sunflower (Helianthus annuus L.). We hypothesized that AM colonization increases Ni content and tolerance in sunflower grown under varying soil Ni concentrations. The combined effect of AM colonization and soil Ni input on the assimilation of nitrogen, in particular the activity of glutamine synthetase (GS), in sunflower plants was also investigated. A factorial experimental design was performed with sunflower cv. Lemon Queen, with or without the AM fungus, Glomus intraradices Schenck & Smith, and treated with 0, 100, 200, or 400 mg Ni kg(-1) dry soil (DS). The AM colonization significantly enhanced plant growth and Ni content, especially at the lower soil Ni treatments. Furthermore, the AM plants exposed to the highest soil Ni level of 400 mg Ni kg(-1) DS had a significantly higher shoot Ni extracted percentage than non-AM plants, suggesting that the AM symbiosis contributed to Ni uptake, then its translocation from roots to shoots. The AM colonization also significantly increased the GS activity in roots, this being likely an indicator of an enhanced Ni tolerance. These findings support the hypothesis that AM symbiosis contributes to an enhanced Ni plant uptake and tolerance and should be considered as part of phytoremediation strategies.

Effects of AM colonization on "wild tobacco" plants grown in zinc-contaminated soil.

This greenhouse study aimed to determine the effect of colonization by the arbuscular mycorrhizal (AM) fungus (Glomus intraradices Schenck & Smith) on the "wild" tobacco (Nicotiana rustica L. var. Azteca), under soil-zinc (Zn) conditions. Plants of N. rustica were grown in AM or non-AM inoculated substrate and subjected to four soil-[Zn] concentrations (0, 50, 100, and 250 mg Zn kg(-1) dry soil). The AM root colonization increased markedly from 14 to 81% with the increasing soil-[Zn] and the mycorrhizal structures were significantly more abundant at the highest soil-[Zn], suggesting that Zn may be involved directly or indirectly in AM root colonization. In addition, total Zn content or Zn concentrations in shoots and roots were shown to increase as soil-[Zn] increased in both AM and non-AM plants. As for the growth parameters studied, there were no significant differences between treatments despite the increase in Zn content or concentration. The AM roots subjected to the highest soil-[Zn] had a significant reduction by about 50% of total Zn content and Zn concentration compared to non-AM roots. Still, the relative extracted Zn percentage decreased dramatically as soil-[Zn] increased. Soil pH was significantly lower in non-AM than AM treatments at the highest soil-[Zn]. In summary, AM plants (particularly roots) showed lower Zn content and concentration than non-AM plants. In this regard, the AM fungi have a protective role for the host plant, thus playing an important role in soil-contaminant immobilization processes; and, therefore, are of value in phytoremediation, especially when heavy metals approach toxic levels in the soil.