Changes in renal function following delivery of the lamb by caesarean section.

Six lambs were delivered by caesarean section at 139 to 145 days of gestation. Birth was associated with a rise in glomerular filtration rate from 4.81 +/- 0.62 to 5.90 +/- 0.74 ml/min and a transient natriuresis secondary to a fall in fractional sodium reabsorption from 93.1 +/- 3.94 to 88.3 +/- 2.29%. This study indicates that in the immediate postnatal period, glomerulotubular balance is disturbed.