Simian Neonatology: I. Gestational Maturity and Extrauterine Viability

Abstract

Abstract. In a 21-month period, 225 simians were born at the New England Regional Primate Research Center. Of these, 141 (63%) survived the neonatal period, and 84 (37%) were either born dead or died during the first 30 days of life. Sixty-two of the 84 neonatal deaths occurred during the perinatal period (0-7 days of life). In four macaque species studied, groups of infants that were high and low survival risks were established by examining weight-specific death rates. Criteria for establishing immaturity by birth weight were suggested in Suguinrrs oedipus and Suimiri sciuresrs.The newborn passes through a critical time, the neonatal period. The ability to adapt to its new environment depends on various factors, among which the length of in utero life plays a decisive role. Gestational age, birth weight, tissue maturity, and neonatal survival data are used to evaluate extrauterine viability in a newborn simian population. Materials and MethodsRecords of all births at the New England Regional Primate Research Center during a 21-month period from January 1969 through September 1970 were reviewed. Birth weights, gestational ages and numbers of stillborn, liveborn, neonatal deaths and survivors were evaluated. Six species of monkeys were studied (table 1). All infants from the four species of macaques were separated from their dams during the first 24 h of life and reared in a nursery. Squirrel monkey and marmoset infants were left with their dams. Each macaque species was divided into birth-weight groups of 50-g increments. Each group within the species was then analyzed for survivors and neonatal deaths. Weight-specific death rates were calculated for each group. Birth weight and degree of tissue maturity were used to evaluate immediate extrauterine viability in Suirniri sciureus and Suguinus oedipus.The neonatal period in this study included birth and the first 30 days of life. The perinatal period included events surrounding parturition and the first 7 days of life.

Mortality in premature mice at birth and during neonatal development

“…Even when additional factors affecting morbidity are present, mortality data related to both birth weight and gestation age are essential for determining the chances of survival of the premature infant (Lubchenco et al, 1972 ;Papiernik, 1977). These results are comparable to those obtained in premature monkey (Digiacomo and Shaughnessy, 1972 ;Price et al, 1972 ;Hird et al, 1975 ;Shaughnessy et al, 1978) and premature piglet (Aumaitre et al, 1979 (Dalle et al, 1978 (Loctin, 1980). al., 1980).…”

Congenital Encephalitozoonosis in a Squirrel Monkey (Saimiri sciureus)

“…The infant was premature by birth weight (70 g) [7] and had a crown-rump measurement of 13.5 cm. The lungs were dark red and uninflated.…”

Simian Neonatology: II. Neonatal Pathology

“…Specimens of tongue, lung, spleen, salivary gland, liver, kidney, and brain (cerebrum) were collected for virological examination from some of the monkeys. The criteria for grouping the newborns according to gestational maturity were birth weight and gestational age [15], and tissue maturity. Table I lists the final diagnoses and major pathological findings in the 82 infants in the study.…”

“…The ability to reduce neonatal mortality improves as our understanding of the physiology of the neonate expands and our knowledge of the prevalent disease of this period increases. Definitions of prematurity and maturity and the association of birthweight with survival in several simian species were the subjects of a previous report [15].Great demands have forced the establishment of nonhuman primate breeding programs. These stem from the fact that certain simian and ape species are endangered, that wild-caught animals are far from optimal experimental animals, and that newborn animals are required for certain studies.…”

“…The ability to reduce neonatal mortality improves as our understanding of the physiology of the neonate expands and our knowledge of the prevalent disease of this period increases. Definitions of prematurity and maturity and the association of birthweight with survival in several simian species were the subjects of a previous report [15].…”