Third Trimester
The
period of maximum cardiac output occurs between week 28 and 35 of the
third trimester. By the end of pregnancy, at about 40 weeks, your
circulating blood volume will have increased to 40 percent to 90
percent above pre-pregnancy levels. The heart depends on an ample blood
supply to ensure adequate delivery of oxygen and nutrients to both
mother and baby. In the third trimester, these changes are critical to
meet the increasing demands of a rapidly growing fetus and also for
preparation for labor. During labor, the heart rate elevates during
contractions and in response to pain.
Warning Signs
Normally,
the healthy heart can withstand the cardiovascular changes that occur
over the course of pregnancy. However, previously unknown heart problems
might become apparent as the pregnancy progresses and the workload
demands on the heart increase. Some common warning signs can include a
racing or pounding pulse, shortness of breath even when at rest,
lightheadedness, fainting spells, a persistent productive cough and
palpitations, or skipped heartbeats.This is why it is so important to
keep all scheduled prenatal appointments with your health care provider.