A comprehensive review of all previous pregnancies
is an important step in the evaluation of women at risk of
preterm birth because the most important historical risk
factor for recurrent preterm birth is a prior spontaneous
preterm birth, including births in the mid-to-late second
trimester (54). It can be difficult to differentiate spontaneous
preterm birth from indicated preterm birth, but an
effort to establish this distinction should be an integral
part of history taking.