Risk factors for spontaneous preterm birth in two urban areas of Ukraine.

The economic, social and health problems faced by former eastern bloc countries after the demise of the Soviet Union are unique in the recent history of Europe. We conducted a study in two urban areas of Ukraine, asking if the traditional predictors of preterm delivery continue to be associated with risk under these conditions. Subjects were pregnant women with last menstrual period (LMP) between 25 December 1992 and 23 July 1994. Self-completed questionnaires and the medical record provided data. We compared 137 spontaneous preterm deliveries with 2,886 full-term births, using all established risk factors for which we had data. Maternal age was the variable most strongly related to preterm birth. Being 18 or less had an odds ratio (OR) of 3.7; being 30+ had an OR of 2.5 relative to the reference group of age 25-29. Placental complications and pre-existing hypertension had ORs of 2.7 and 2.3, respectively, but the confidence interval included 1.0. Low net pregnancy weight gain (less than 10 kg) was significantly associated with preterm birth, but the rate of net weight gain was not. Marital status and educational category were only weakly related. We conclude that although Ukraine faced serious difficulties during its transition to a market economy, these problems did not generally alter the outcome of pregnancy in our sample when the classic risk factors for preterm delivery were present.

Semen analysis and fertility assessment in rabbits: statistical power and design considerations for toxicology studies.

Semen analysis is commonly used in evaluating human response to reproductive toxicants. Serial semen samples can be collected from rabbits and fertility assessed by artificial insemination, hence this species is potentially well suited for male reproductive toxicity studies that might be extrapolated to humans. However, the size and cost of rabbits often restricts the number of animals used, reducing the sensitivity of such studies. Therefore, it was of interest to optimize study design for semen analysis and fertility assessment in rabbits. Semen samples were collected weekly from sexually mature New Zealand white rabbits and a range of parameters was analyzed (Semen--pH, volume, osmolality; Sperm--number and concentration, morphology, viability, percentage motility, motion characteristics; Seminal plasma--fructose, citric acid, carnitine and protein concentrations, acid phosphatase activity). Male fertility was assessed by inseminating female rabbits with the minimum number of motile sperm required for normal fertility, determined to be one million. The within- and between-buck variabilities were determined for all parameters and used to calculate the statistical power of different study designs. The variability of sperm number and concentration was decreased when measured in four ejaculates collected within a short period of time rather than in a single ejaculate; this was not true of other endpoints measured. In addition, use of preexposure observations further increased the statistical power for all of the parameters. These data can be used to determine the optimum design for studies of male reproductive toxicity using rabbits, with particular regard to cost and the number of animals used.