1) Prolonged labor is defined as labor exceeding 18 hours for the first and second stages combined. It can be caused by cephalopelvic disproportion (CPD) where the fetal head is too large for the maternal pelvis.
2) CPD can be absolute due to a permanently contracted pelvis or relative due to fetal malpositions or malpresentations. Management depends on the degree of disproportion and may include a trial of labor or cesarean section.
3) Careful monitoring during labor is important when there is suspected CPD to detect complications early and intervene if needed to deliver the baby safely.