Hi,
I had the same question re: my pregnancy and aortic insufficiency. If the leak is severe, you'll need to see your cardiologist as well as a high risk OB and neonatal specialist to monitor you and your developing baby. My leak was not severe, but progressed during the pregnancy and I became symptomatic.
I had to wear lovely maternity support hose and take baby aspirin after developing phlebitis, (blood clots are a higher risk for us). I kept my legs elevated for most of the pregnancy.
Regarding Labor, I cannot emphacize how important it is to trust your instincts. Be assertive with your attending nurses and physicians, telling them exactly how you're feeling. Everyone's different; tolerance varies. To my cardiologist's surprise, my heart did not tolerate the stress of Labor, despite my fitness level and low weight.
Here's some good advice I got from Web MD:
"Anyone diagnosed with valvular regurgitation (insufficiency, a leaking valve or valves, can remain stable or progress at different rates, case by case dependent, drugs can treat the symptoms but they don't cure the cause) should be under the care and close monitoring of a good (competent and compassionate) interventional cardiologist.
Valvular regurgitation levels go from trace or physiologic (minimal or trivial, often seen in otherwise heart-healthy individuals) to mild to moderate to severe. Echocardiography grading scale is 0-4+."
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You'll need a strong support system if you become symptomatic. I spent most of the time in bed, save my walks which were an important component of my physical, spiritual and psychological well-being.
Check out these links for more info:
http://www.americanheart.org/presenter.jhtml?identifier=9601
http://www.heartcenteronline.com/myheartdr/common/articles.cfm?ARTID=187
http://www.postgradmed.com/issues/2001/08_01/prasad.html
God bless,