Erythrocyte filterability and adenosine triphosphate levels in normal pregnancy and puerperium

The filterability of erythrocytes was determined by a filtration method using erythrocytes suspended either in phosphate-buffered saline or in native plasma. Erythrocytes from pregnant women in the second and third trimester were significantly less filterable than those from non-pregnant women. On 0 to 1 day after delivery, erythrocyte filterability was further reduced, being significantly lower than that in the third trimester of pregnancy. Erythrocyte adenosine triphosphate (ATP) levels during pregnancy were not significantly different but in early puerperal period it was significantly lower than that in non-pregnant women. One month after delivery the filterability and ATP content of erythrocytes returned to the non-pregnant levels. The size and hemoglobin concentration of erythrocytes were unchanged during pregnancy and puerperium.