**8. Conclusion**

For a full-term newborn, vaginal delivery means to deliver the baby at a gestational age of 37–42 weeks, from the mother's first day of the last menstrual period. This is determined by an accurate history taking from the mother or by ultrasonographic dating and evaluation. Some mothers, for one reason or another, may not adequately know their first day of the last normal menstrual period. In this case, reliance on history from the mother may be misleading. However, the Naegel rule is the use of a commonly known formula to predict the expected date of devilery. The formula is based on the date of the first day of the last normal menstrual period of the mother. The rule assumes a menstrual cycle of 28 days and mid-cycle ovulation, at 14 day from the first normal menstrual day. This means that the formula may not be applicable for women whose cycles are either less than 28 days or more than 28 days and whose ovulation may occur before or after day 14. In this case, however, ultrasonographic dating can be much more accurate, especially if it is done in early pregnancy, before 12 weeks of gestation. Ultrasonographic dating done earlier than 12 weeks are more accurate than those done at 12 weeks or above 12 weeks. Again, this might depend on the level of experience and knowledge of the user of the ultrasound

machine. Vaginally, approximately 11% of singleton pregnancies are delivered preterm whereas 10% of all deliveries are post-term. Good knowledge of normal vaginal deliveries thus, forms the basis for management of complicated deliveries.
