A woman comes with postdated pregnancy at 42 weeks. The initial evaluation would be:
Induction of labour
Review of previous menstrual history
Cesarean section
USG
A pregnancy continuing beyond two weeks of the expected date of delivery (> 42 weeks or >294 days) is called postmaturity or post-term pregnancy. Pregnancy between 41-42 weeks is called prolonged pregnancy.
Most common cause of post term pregnancy is wrong dates so, a careful review of menstrual history is important in all
such cases –
“If the patient is sure about her date with previous history of regular cycles, it is a fairly reliable diagnostic aid in the calculation of the period of gestation. But in cases of mistaken maturity or pregnancy occurring during lactational amenorrhoea or soon following withdrawal of the pill’, confusion arises. In such cases, the previous well documented antenatal records of first visit in first trimester if available, are useful guides.”
Dutta Obs. 6/e, p 319
Once the menstrual history is confirmed, investigations like USG and amniocentesis are done:

To confirm fetal maturity
To detect any evidence of placental insufficiency