Blood volume in newborn piglets: effects of time of natural cord rupture, intra-uterine growth retardation, asphyxia, and prostaglandin-induced prematurity.

Blood volume (BV), red cell mass (RCM; Cr-51) and plasma volume (125I-labeled albumin) were measured in 205 piglets from 28 litters shortly after birth. Spontaneous cord rupture in healthy piglets occurred during delivery (n = 25) or within 190 sec of birth (n = 82). Spontaneous and induced delay of cord rupture resulted in a time-dependent increase in BV and RCM. BV (x +/- S.D.) at birth was 72.5 +/- 10.5 ml/kg (RCM, 23.6 +/- 4.6 ml/kg) in the 25 piglets with prenatal cord rupture and 110.5 +/- 12.9 ml/kg (RCM, 38.4 +/- 7.0 ml/kg) in 17 piglets with late spontaneous cord rupture. The mean blood volume of all the 107 healthy piglets with spontaneous cord rupture was 90.2 +/- 12.7 ml/kg (RCM, 30.1 +/- 4.8 ml/kg). RCM was significantly (P less than 0.05) increased in nine piglets with intra-uterine growth retardation (RCM, 35.8 +/- 11.2 ml/kg) and in 13 with metabolic acidosis but without signs of asphyxia (RCM, 35.8 +/- 6.7 ml/kg). In five piglets with cord wrapping, prenatal cord rupture, and acute asphyxia, BV (57.8 +/- 7.3 ml/kg) was significantly decreased. In five other piglets with prenatal cord rupture and acute asphyxia, BV (67.9 +/- 10.0 ml/kg) corresponded to that of the normal piglets with prenatal cord rupture. However, delay of cord rupture to 60 sec after birth did not increase BV (66.0 +/- 11.8 ml/kg) in four piglets with acute asphyxia. Forty-one premature piglets delivered 6 days before normal term had their cords ruptured prenatally or within 5 sec of birth. Their hematocrit at birth (0.337 +/- 0.028 liters/liter) was significantly decreased compared to the normal full-term piglets with corresponding time of cord rupture (0.384 +/- 0.033 liters/liter). RCM in 18 piglets with prostaglandin-induced prematurity (18.9 +/- 3.4 ml/kg) was significantly lower than in 23 piglets whose births had been induced by ovarectomy of their mother (RCM, 22.1 +/- 3.2 ml/kg).