In vitro fertilization and risk for hypertensive disorders of pregnancy: associations with treatment parameters

With an increasing proportion of pregnancies being conceived using assisted-reproductive technology, important changes to in vitro fertilization (IVF) such as the use of cryopreserved oocytes or embryos have been made. It is now established that adverse maternal and infant perinatal outcomes are associated with both assisted reproductive technologies and subfertility

Estimating the prevalence of malformation of the heart in the first year of life using capture-recapture methods

The authors estimated the prevalence of heart malformation during the first year of life, using five data sets with varying degrees of completeness from two English regional health authorities. These areas covered a total population of 6, 872, 000. Analysis was carried out using capture-recapture methods, including log-linear modeling, on data collected between June 1993 and August 1994. A large number of cases in the community were unrecorded by any of the current sources of information. In South East Thames, where an antenatal training screening program for detecting heart malformations had been implemented in the late 1980s, the estimated prevalence rate varied from 5.5 per 1, 000 births (95% confidence interval (Cl): 3.5, 10.8) to 9.0 per 1, 000 births (95% Cl: 6.4, 14.2), depending on the assumptions in the model and the number of sources used in the analysis. In the Wessex region, which did not have a formal training program, prevalence was lower and varied little, from 4.3 per 1, 000 (95% Cl: 3.4, 6.0) to 5.1 per 1, 000 (95% Cl: 4.0, 7.2), according to assumptions. These two estimates were reasonable rates in comparison with reports in the literature. This analysis was helpful in demonstrating that the training program designed to identify servere heart malformations during the antenatal period in one of these regions had no lasting impact on prevalence

Probing fission time scales with neutrons and GDR gamma rays

The time scales for nuclear fission have been explored using both pre- and postfission neutrons and GDR gamma rays. Four systems were investigated: 133-MeV /sup 16/O+/sup 176/Yb and /sup 208/Pb and 104-MeV /sup 4/He+/sup 188/Os and /sup 209/Bi. Fission fragments were measured in coincidence with PPACs. The neutrons were detected using eight detectors from the DEMON array, while gamma rays were measured using the US BaF/sub 2/ array. The pre- and postfission gamma rays were determined using moving source fits parallel and perpendicular to the fission fragment emission directions. The time scales for fission for the neutrons were determined using the neutron clock technique. The gamma-ray data were fitted using a statistical model calculation based on the code CASCADE. The results of the fits from both data types were used to extract nuclear friction coefficients, gamma , and fission time scales. The gamma values ranged from 7 to 20, while the fission times were (31-105)*10/sup -21/s