Changes occur constantly throughout the body during pregnancy. At this point some doctors will perform an internal exam to check for early cervical changes. A small tear or rip can indicate an early delivery.
At 33weeks of Pregnancy,normal contractions are usually irregular or open the cervix. If these contractions become regular ,they may be preterm labor contractions, which cause the cervix to change.
At 33 weeks of pregnancy your cervix should be a hard as ever and long, a short or thinning cervix would be a sign of preterm labor and a reason for alarm.