The heart is an amazing organ, synchronizing the entrance and then ejection through two different systems, depending on whether the blood is oxygen-rich or oxygen-depleted. It has four chambers, and the blood in each chamber is separated from the other chambers by a trap door effect of valves that slam shut then open repeatedly with each stroke of the heart. If there's damage to the valves, then blood can leak forward or be forced backwards.
The mitral valve sits between the left atrium and the left ventricle. Oxygenated blood from the lungs flows into the left atrium, and then passes via the mitral valve gatekeeper to the left ventricle in preparation for the burst of propulsion to the aorta. In MVP, the valve is weakened by causes unknown, and flaps backwards into the left atrium during the ejection of blood from the left ventricle. Although MVP can be associated with many serious heart defects, it is usually a benign condition that merely provokes disturbingly weird symptoms.
Palpitations, then anxiety (either because of the palpitations or along with them), shortness of breath, unusual chest pains, and panic attacks are famously associated with MVP. It is difficult to separate the anxiety with as opposed to the anxiety because of the palpitations and chest pain, but the cluster is certainly a legitimately recognized symptom complex attributed to MVP. It's no fun to suffer from symptomatic MVP. In addition to the above discomforts, there are also the psychodynamics of not being taken seriously at the doctor's office. Anger, embarrassment, and the added expense of rotating doctors only make life worse.
It might be expected to be worse in pregnancy, since the increase in blood and plasma and the changes in cardiac activity that are normal in pregnancy should challenge the valvular system more than usual. But actually MVP improves in pregnancy in most women, because the physical changes in the heart tend to realign the mitral valve components into a more normal position.
With most pregnant women who have MVP being symptom-free, the biggest concern is whether to treat them with antibiotics at delivery as would be done with patients with other valve damage. Dentists often treat MVP patients with antibiotics before dental procedures, so patients may expect them at the time of delivery. But the current thinking is to forego any antibiotics unless there are abnormalities of heart function along with the MVP or complicated deliveries. Uncomplicated vaginal or Cesarean deliveries don't necessarily need the antibiotics for just the MVP.
In summary, mitral valve prolapse for the most part poses no challenge in pregnancy, and its symptoms are even seen to improve. In fact, if there are troubling symptoms one should suspect another cardiac condition that may have not been challenged enough to be obvious before pregnancy.