Mommy Mondays: Pregnancy and your Respiratory/Cardiovascular Systems

Respiratory System

Oxygen enables us to live. All our cells need oxygen. With every breath you take, it flows through your system to the fetus through the placenta and umbilical cord, helping the cells of the developing fetus multiply and grow.

Because of the growing uterus, your lung space is diminished causing you to breathe more often to compensate. But your lung function improves during your pregnancy by 40 to 50% which helps when you are breathing that much more. There will be times when you feel flushed or short of breath, as if you just ran a flight of stairs, even if you didn’t. Relaxation and breathing techniques are great ways to help offset this problem.

If you feel short of breath during exercise, SLOW DOWN, CATCH YOUR BREATH, and DO NOT RESUME until breathing is back to normal. It is not a reason for you to STOP working out altogether as you lungs have the ability to increase their capacity, especially during exercise or severe stress.

As the uterus continues to grow, it will begin to push up into your diaphragm (the muscle that stretches downwards when you inhale to allow lungs to fill up with oxygen and then rises back up when you exhale to expel the carbon dioxide) reducing the room it has to stretch downwards. But your pregnant body has an incredible adaptive mechanism-it can flare your rib cage out sideways and backward to make room for your lungs to expand. The pregnancy hormone relaxin helps out by softening the muscles between the ribs (the same way it helps with your hip joints). Practice expanding your rib cage by lifting your arms out to the side or over your head. After your baby “drops” and settles head down toward the end of your pregnancy, the breathing will become easier again.

Cardiovascular System

With your body going through so many changes, its demand for more oxygen and nutrients increases. Your heart and blood vessels also go through a dramatic change to transport more oxygen, not jus to the fetus, but also to all of the involved organs that are working a lot harder. Your cardiac output (the amount of blood pumped by your heart) increases by 40 to 50 %, so that there is always enough blood to carry nutrients and oxygen to the fetus. Expect your resting heart rate to go up by up to 20 beats per minute higher than normal (this will throw your training heart rate off-however, your maximum training heart rate will not change, but you will reach it quicker with less work). Heart rate can also vary depending on the time of day, eating habits, stress levels, sleep patterns, and age. (a 40 year olds training heart rate can be 10 to 20 beats slower than a 20 year old’s) Drinking a lot of water of can help keep your heart rate down.

To make sure its getting all this done, the heart will grow a little bigger as well. Blood pressure can be expected to be lower and heart rates faster. With extra blood and relaxed arteries during pregnancy, your heart pumps more often but does not need to work quite as hard with each beat. The end result is usually lower blood pressure.

Check your blood pressure regularly (every month is good). If it goes up, exercises should be chosen with care and workouts monitored by a professional. Depending on the severity of the condition, you may even have to stop working out altogether. Gestationally induced high blood pressure could cause growth retardation and other complications for the fetus.

The cardiovascular output can be altered by your body position. Standing still for long periods of time can cause blood pooling in your legs, so it is best to keep moving! Avoid lying still on your back after the 16th week. In a supine position (on your back), the uterus falls back and places pressure on your vena cava (the main blood returning vein), reducing blood flow. This will cause dizziness and may put your baby’s health in jeopardy. Lie on your left side instead. Exercising in general will promote proper circulation and venous return.

Next week, we will look at how pregnancy affects your disposal and endocrine systems.

Until next time Mommys, try to balance your breathing and relaxation time with movement and exercise!


Health respect & happiness,

Beki