Intraventricular hemorrhage in preterm infants: declining incidence in the 1980s.

Ultrasound has been routinely used since late 1979 to diagnose periventricular-intraventricular hemorrhage in infants whose gestational age was 34 weeks or less. During the years 1980 to 1987 the ultrasound scans were interpreted by one person, and a steady decline in incidence of periventricular-intraventricular hemorrhage was observed. Both for infants of 34 weeks or less and for very low birth weight (less than 1500 g) infants, periventricular-intraventricular hemorrhage incidence decreased, respectively, from 34% and 39% in 1980 to 1981 to 19% and 25% in 1986 to 1987. This decrease was confined to true intraventricular hemorrhages, which decreased from 22% in 1980 to 1981 to 7% in 1986 to 1987 for infants of less than or equal to 34 weeks' gestation. These results were not influenced by a change in the distribution of birth weights or gestational ages of the infants evaluated nor by a change in the inborn to outborn ratio. The incidence of periventricular-intraventricular hemorrhage was lower in infants born by cesarean section than those delivered vaginally, but the decrease could not be attributed to an increased number of deliveries by cesarean section. Although there were undoubtedly changes in neonatal care during this time period, no planned intervention occurred. It was concluded that pharmacologic intervention studies must be interpreted with caution.

The Yucatan minature pig as a laboratory animal.

Parent stock for a minature pig herd was obtained from the progeny of pigs imported from the Yucatan Peninsula of Mexico. The Yucatan miniature pig is slate-gray, essentially hairless, and has a docile temperament. The tractable nature of this pig minimized risks for animal handlers as well as researchers. With regular human contact, these pigs became amenable to handling and tolerated restraint well. The mean birth weight was 0.74 kg, and the mean weaning weight at 60 days was 6.47 kg. The mean weight of mature nonobese boars was 83 kg while mature sows averaged 70 kg. The height and length for mature pigs of both sexes averaged 57 cm and 76 cm, respectively. The mean range of plasma glucose was 86-117 mg/dl during the first 8 weeks of life. The Yucatan miniature pig is native to tropical regions. The Colorado cold winter weather caused life-threatening stress to animals housed outside; therefore, intensive management procedures were required during the winter months.