All of the following changes are seen in pregnancy except :
CARDIAC OUTPUT: Increases from 5th week of pregnancy, reaches its peak 40-50% at about 30-34 weeks. Thereafter the CO remains static till term. CO is lowest in the sitting or supine position and highest in the right or left lateral or knee chest position. Cardiac output increases fuher during labor (+50%) and immediately following delivery (+70%) over the pre-labor values. MAP also rises. There is squeezing out of blood from the uterus into the maternal circulation (auto transfusion) during labor and in the immediate postpaum. CO returns to pre-labor values by one hour following delivery and to the pre-pregnant level by another 4 weeks time. The increase in CO is caused by: (1) Increased blood volume (2) To meet the additional O2 required due to increased metabolic activity during pregnancy. The increase in CO is chiefly affected by increase in stroke volume and increase in pulse rate to about 15 per minute. BLOOD PRESSURE: Systemic vascular resistance(SVR) decreases (-21%) due to the smooth muscle relaxing effect of progesterone, NO, prostaglandins or ANP. Reference: Dutta's Textbook of Obstetrics 7th edition page 53
Increased stroke volume
Increased cardiac output
Increased Intravascular volume
Increased peripheral vascular resistance
General obstetrics