Single embryo transfer reduces the risk of perinatal mortality, a population study.

STUDY QUESTION: Do births following single embryo transfers (SET) have a reduced risk of perinatal mortality compared with those following double embryo transfers (DET)? SUMMARY ANSWER: SET is associated with reduced risk of perinatal mortality compared with DET. WHAT IS KNOWN ALREADY: Fetal, neonatal and perinatal mortality are important indicators for monitoring pregnancy and childbirth, particularly for births following assisted reproductive technology (ART) treatments. Following the introduction of SET, there has been a decline in the perinatal mortality rate (PMR) among babies born after ART in Australia and New Zealand. STUDY DESIGN, SIZE, DURATION: This population study (census) included 50,258 births of ≥ 20 weeks gestation and/or ≥ 400 g of birthweight following embryos transfer cycles in Australia and New Zealand during the period 2004-2008. PARTICIPANTS/MATERIALS, SETTING, METHODS: The PMR was calculated according to the number of embryos transferred and other demographic and treatment-related factors. Perinatal deaths were defined as the number of fetal deaths (stillbirths) plus the number of neonatal deaths (deaths that occur before 28 days after birth). MAIN RESULTS AND THE ROLE OF CHANCE: The PMR was 16.2 per 1000 births (n= 813). Of the 813 perinatal deaths, 630 were fetal deaths and 183 neonatal deaths. Twins had a significantly higher PMR (27.8 per 1000 births) than singletons (12.4 per 1000 births). The risk of perinatal mortality for all births following DET was 53% higher than for all births following SET (adjusted risk ratio 1.53, 95% confidence interval (95% CI): 1.29-1.80). Births following fresh DET had a 58% increased risk of perinatal mortality compared with births following fresh SET (risk ratio 1.58, 95% CI: 1.32-1.90). LIMITATIONS, REASONS FOR CAUTION: Information on outcomes was missing from <1% of clinical pregnancies recorded in Australian and New Zealand Assisted Reproduction Database for the study period. There are no data on the timing of fetal death, the cause of perinatal death or on late termination of pregnancy at ≥ 20 weeks' gestation. WIDER IMPLICATIONS OF THE FINDINGS: Double and higher order embryo transfer is associated with a higher risk of perinatal mortality when compared with SET. The number of embryos transferred is determined by the clinician with consent of the patient and is a modifiable treatment factor. SET should be advocated as the first-line management in ART as it is the single most effective public health intervention for preventing excess perinatal mortality among ART pregnancies. STUDY FUNDING/COMPETING INTEREST(S): Nil.

Investigating maternal risk factors as potential targets of intervention to reduce socioeconomic inequality in small for gestational age: a population-based study.

BACKGROUND: The major aim of this study was to investigate whether maternal risk factors associated with socioeconomic status and small for gestational age (SGA) might be viable targets of interventions to reduce differential risk of SGA by socioeconomic status (socioeconomic SGA inequality) in the metropolitan area of Vancouver, Canada. METHODS: This study included 59,039 live, singleton births in the Vancouver Census Metropolitan Area (Vancouver) from January 1, 2006 to September 17, 2009. To identify an indicator of socioeconomic SGA inequality, we used hierarchical logistic regression to model SGA by area-level variables from the Canadian census. We then modelled SGA by area-level average income plus established maternal risk factors for SGA and calculated population attributable SGA risk percentages (PAR%) for each variable. Associations of maternal risk factors for SGA with average income were investigated to identify those that might contribute to SGA inequality. Finally, we estimated crude reductions in the percentage and absolute differences in SGA risks between highest and lowest average income quintiles that would result if interventions on maternal risk factors successfully equalized them across income levels or eliminated them altogether. RESULTS: Average income produced the most linear and statistically significant indicator of socioeconomic SGA inequality with 8.9% prevalence of SGA in the lowest income quintile compared to 5.6% in the highest. The adjusted PAR% of SGA for variables were: bottom four quintiles of height (51%), first birth (32%), bottom four quintiles of average income (14%), oligohydramnios (7%), underweight or hypertension, (6% each), smoking (3%) and placental disorder (1%). Shorter height, underweight and smoking during pregnancy had higher prevalence in lower income groups. Crude models assuming equalization of risk factors across income levels or elimination altogether indicated little potential change in relative socioeconomic SGA inequality and reduction in absolute SGA inequality for shorter height only. CONCLUSIONS: Our findings regarding maternal height may indicate trans-generational aetiology for socioeconomic SGA inequalities and/or that adult height influences social mobility. Conditions affecting foetal and childhood growth might be viable targets to reduce absolute socioeconomic SGA inequality in future generations, but more research is needed to determine whether such an approach is appropriate.

Rectovaginal fascia: An important structure in pelvic visceral surgery? About its development, structure, and function.

BACKGROUND: The existence, development, and function of the rectovaginal fascia has been discussed in literature. In women, a defect in the fascia leads to rectoceles and severe constipation. In pediatric textbooks for anorectal or urogenital surgery, however, it is not mentioned. Does the fascia exist in children? METHODS: The pelvises of 31 female and, as controls, 31 male fetuses (age from 9 weeks of gestation to newborn) were plastinated. Sections (transversal, sagittal, and frontal) were stained with azure II/ methylenblue/ basic fuchsin and viewed at a magnification of 6.5x to 80x. In addition, the authors investigated macroscopically and microscopically the rectovaginal fascia in 1 fetal and 1 adult cadaver. RESULTS: At the beginning of the fetal period the authors recognized the anlage of the rectovaginal fascia caudal from the rectouterine excavation. Later, a fascia of connective tissue develops. It is connected directly to areolar connective tissue at the dorsal wall of the vagina. Neurovascular bundles are situated ventrolaterally of the rectal wall. At the level of the anorectal flexure this fascia separates the rectum and the vagina. CONCLUSIONS: Our investigations indicate that the rectovaginal fascia is completely developed in newborns, through differentiation of mesenchyme, which develops into a fascia. It protects different compartments and serves as an abutment to the rectal wall. Thus, it is important for adequate bowel emptying. For the surgeon it is a leading structure for preventing nerve damage of the autonomic nerve supply of the pelvic organs. It should be known, protected, and, if necessary, reconstructed.