Page 15, Later Development, Develop. Physiol., Dr. D. Penney

Neonatal Circulation:

An adult circulatory pattern does not result instantaneously from the birth changes just described (Figure 3.08). Instead, a "transitional" or "neonatal" circulation exists, which has some characteristics of both the fetal and the adult circulations. Some shunting continues, right to left through the foramen ovale, and left to right through the ductus arteriosus. Thus the outputs of the right and left hearts are not yet identical as they will become in the adult circulation.

(Table 3.10) shows data for normal human infants 10 hours after birth. The outputs of the left ventricle and right ventricle are clearly different, 348 and 233 ml/kg/min, respectively. This means that left to right shunt, presumably through the ductus arteriosus, is 38%, while right to left shunt, presumably through the foramen ovale, is 20%.

(Table 3.12) shows the pressures at various sites in the circulation of a newborn lamb.

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