The effect of mode of delivery on neonatal mortality in very low birthweight infants born in Victoria, Australia: Caesarean section is associated with increased survival in breech-presenting, but not vertex-presenting, infants

To determine whether the improved survival of very low birthweight (VLBW) infants (< 1500 g) born in Australia can be attributed to currently high rates of Caesarean section, we examined the associations between neonatal mortality and Caesarean section in singleton liveborn VLBW infants (500–1499 g) born during 1986–93 in Victoria, Australia, using data from the Victorian Perinatal Collection Unit. The infants included in this study had completed > 23 weeks of gestation, had no life-threatening malformations and had not been delivered by a repeat Caesarean without a trial of labour (n = 2763). For infants weighing 500–749 g, 750–999 g, 1000–1249 g and 1250–1499 g, the neonatal mortality rates were 56.1%, 25.7%, 13.0% and 4.3% respectively, and the Caesarean section rates were 33.1%, 42.3%, 54.8% and 55.8%. Nearly half of these births (n = 1269) were associated with one or more obstetric indications for Caesarean section (non-breech malpresentaion, fetal distress, prolapsed cord, placenta praevia, pre-eclampsia and hypertension). Overall, the odds ratio (OR) for neonatal death associated with Caesarean section was 0.92 [95% confidence interval 0.60–1.41], after adjustment for gestational age, birthweight, year of birth, type of hospital, presence or absence of labour, presentation and obstetric indications for Caesarean section. However, when the vertex-presenting (n = 1702) and breech-presenting (n = 746) infants were considered separately, the adjusted ORs for neonatal death were 1.98 [0.96–4.10] and 0.52 [0.29–0.96] respectively. For those infants without obstetric indications for Caesarean section, the adjusted ORs for neonatal death in vertex-presenting (n = 950) and breech-presenting (n = 446) infants were 3.80 [1.11–13.0] and 0.47 [0.23–0.6]. These recent population - based data support the view that Caesarean section does not enhance the neonatal survival of VLBW babies when obstetric complications are absent.     

Effects of diflubenzuron on limb regeneration and molting in the fiddler crab, Uca pugilator

Fiddler crabs, Uca pugilator, were exposed to the insect growth regulator diflubenzuron (Dimilin^®) at 0.5, 5, and 50 μg/l after multiple autotomy of one chela and five walking legs. Regeneration of the first walking leg was monitored, and time to ecdysis, mortality, and morphology of the regenerated limbs observed. Continuous exposure to the chemical produced a dose-dependent retardation of regeneration. Animals molting in the higher concentrations exhibited significant mortality at ecdysis. Exposure to the pesticide for a single week produced similar but less severe effects. However, if crabs molted while in the pesticide, significant mortality was observed. The presence of sediment in the container with the crab moderated the effects of the pesticide, but did not eliminate them.

The regenerated limbs of the crabs that survived ecdysis were found to have lesions in the form of black areas in which the cuticle was improperly developed. These lesions were seen in crabs that had been in the pesticide for only one week (week 2 or week 3) as well as those that had had continuous exposure. They were also seen in crabs that regenerated in Dimilin with sediment. In addition, the number of setae on limbs was reduced compared to the number on limbs that had regenerated in clean sea water.     

Invited commentary

World Journal of Surgery -     

Sample size considerations when groups are the appropriate unit of analysis.

This article discusses issues to be considered by nurse researchers when groups should be used as the unit of randomization. Advantages and disadvantages are presented, with statistical calculations needed to determine the effective sample size. Examples of these concepts are presented using data from the Black Cosmetologists Promoting Health Program. Different hypothetical scenarios and their impact on sample size are also presented. Given the complexity of calculating the sample size when using groups as the unit of randomization, it is advantageous for researchers to work closely with statisticians when designing and implementing studies that anticipate the use of groups as the unit of randomization.     

Survival Strategies for Nurse-Midwifery Students

Nurse-midwifery students face multiple stressors in their educational experience. Strategies to resolve stress and promote adaptation to the new role are examined and measures used to promote students' adaptation to the educational experience are described.