Nomenclature for pregnancy outcomes: time for a change.

Traditionally, obstetricians have grouped together all pregnancy losses before the mid-second trimester as spontaneous abortions. However, this nomenclature is arbitrary, outdated, and not clinically useful. Using this system, miscarriages due to genetic abnormalities, fetal deaths associated with abnormal placental growth and development, and spontaneous preterm births of liveborn fetuses at previable gestations are lumped together in a single category. In addition, the term abortion is fraught with emotional connotations for families suffering the loss of a pregnancy. Thus, whereas the existing classification for pregnancy loss has served a somewhat pragmatic role, it ignores precepts of developmental biology and the clinical realities of these adverse pregnancy outcomes. In this article, we propose a more useful nomenclature for pregnancy loss and preterm births that is informative and is based on developmental periods in gestation and shared pathophysiology.