You will hear many expectant mothers claim that their hearts are full. Of course, we assume these women are referring to the love they have for their anticipated baby. And, in almost every case, we assume correctly.
But, mother's hearts are even more amazing than we can ever imagine. An expectant mother's heart (or cardiac) function changes greatly while she carries her child. These changes include heart rate, cardiac output and blood volume. According to information found at www.merckmanuals.com, a woman's heart must work harder during pregnancy because the heart must pump more blood to the uterus while the fetus grows. In fact, by the end of a pregnancy, the uterus is receiving one fifth of the woman's pre-pregnancy blood supply!
The normal heart rate in a non-pregnant woman is between 60 and 100 beats per minute. But, during pregnancy, the heart rate increases an average of 15 to 20 beats per minute. Most of this increase comes at the beginning of the last trimester and remains throughout the pregnancy.
Additionally, the amount of blood pumped by the heart (the cardiac output) increases by 30 to 50%! Not surprisingly, when a pregnant woman engages in exercise, cardiac output and heart rate increase more than when the same woman is not pregnant. Then, at about 30 weeks into the pregnancy, cardiac output declines slightly. But, during actual labor, cardiac output increases by an additional 30%! After delivery, cardiac output decreases (rapidly at first and then more slowly). Generally, cardiac output returns to pre-pregnancy level about six weeks after delivery.
And, a pregnant woman's blood volume increases by almost 50% during pregnancy! The amount of fluid in the blood increases more than the number of red blood cells (which carry oxygen). So, even though there are more red blood cells, blood tests may indicate mild anemia due to the higher fluid level. This is normal and is not usually a reason for alarm.
Learning about a growing baby's development is always amazing. But, equally amazing is the ability of a mother's body (and heart!) to accommodate to and provide for the ever-changing needs of her child.
Washington Irving once said, "There is , in every true woman's heart, a spark of heavenly fire." In the case of the pregnant woman we now know there is that and SO much more!
photo courtesy of pixabay.com