during 1 St pregnancy, head may engage at a later stage, during labour process, though it's considered good to have head as engaged.
check for pelvic bone parameters through ultrasound, feto pelvic disproportion, means the pelvic bone is narrow to house the head
your doctor will either induce pains at 40 weeks or you will get natural labour pains or the bag will rupture
the process and medicines for augment labour will be decided according to the above factors
good luck