Women with congenital heart disease who become pregnant or discover heart disease during pregnancy are at increased risk for life-threatening complications for themselves and their unborn baby. Pre-pregnancy cardiology is the best way to prevent possible risks.

During normal pregnancy, hormonal changes in the female body cause an increase in both plasma volume (due to water and salt retention) and blood cell volume (due to increased red blood cell count). The disproportionate increase in these two factors in the blood causes physiological anemia in pregnant women.