I have this too, hope this helps!
Almost everyone has palpitations from time to time, though many women experience them more frequently during pregnancy for a variety of reasons.
Increased Blood Volume
A pregnant woman's body contains far more blood---up to 50 percent more---than that of a non-pregnant woman, explain Heidi Murkoff and Sharon Mazel, in their book "What To Expect When You're Expecting." This provides for the needs of the growing baby by ensuring that there's plenty of blood for both mother and fetus. Unfortunately, a pregnant woman must move that significantly enhanced blood volume around her body with the very same heart she relies upon while not pregnant, meaning that the heart has to work much harder during pregnancy than during other times. The increased workload forces the heart to beat with greater force and more frequently in order to keep blood pressure adequate; this results in more frequent "errors" in heartbeat---moments during which the beat becomes a bit asynchronous---and these errors are felt as palpitations. Typically, they last only a few seconds, and are generally not accompanied by any other symptoms.
Read more: https://www.livestrong.com/article/...-palpitations-during-pregnancy/#ixzz1jfPr0vA3