Physiological Adjustment of Arterial Blood Gases and Bicarbonate ION During Pregnancy in Human

In the present study the partial pressure of oxygen (PaO 2 ), carbon dioxide (PaCO 2 ) and bicarbonate ion (HCO 3 - ) in arterial blood were estimated in 32 women in Dhaka city. For this purpose a total of 32 women subjects with age ranged from 25 years to 35 years without any recent history of respiratory diseases were selected. Of those, 8 healthy non-pregnant women were included as control and 24 normal pregnant women as experimental group. The PaO 2 , PaCO 2 and HCO 3 - were estimated during the first, second and third trimester by using 'easy blood gas auto analyzer'. The PaO 2 was significantly higher during entire pregnancy period. However, the PaCO 2 and HCO 3 - were significantly lower in first, second and third trimester of pregnant women than that of non-pregnant women. There were no statistically significant difference of PaO 2 , PaCO 2 and HCO 3 - ion among first trimester, second trimester and third trimester. The progressively increased PaO 2 , decreased PaCO 2 and HCO 3 - ion throughout the pregnancy is possibly due to the effect of progesterone causing hyperventilation. DOI: 10.3329/bjpp.v23i1.5724 Bangladesh J Physiol Pharmacol 2007; 23(1&2) : 10-12