Mean Duration of Pregnancy in Spontaneous Deliveries in Ahwaz University Affiliated Hospitals in ۲۰۰۷

Background & Aims: Accurate knowledge about gestational age is very important in taking decision for pregnancy management and termination. According to Naegele’s rule the length of pregnancy is ۲۸۰ days after LMP and according to studies performed in Harvard University, duration of pregnancy in nullipare and multipare women has been respectively ۲۸۸ and ۲۸۳ days and according to a study performed in Oxford University it is influenced by factors such as age, parity, some illnesses and personal habits. Materials and methods: In this retrospective study, all laboring women admitted in Ahwaz Medical University Hospitals in ۲۰۰۷ including ۶۸۹ nulliparas and ۷۷۴ multiparas with true labor pain and reliable LMP were studied for pregnancy duration. Data were analyzed by SPSS software. Results: Mean duration of pregnancy was ۲۷۳.۱۷, ۲۷۴.۳۱and ۲۷۳.۷۷ days in nulliparas, multiparas and overall respectively. Parity has no significant association with pregnancy duration. According to the sonography below ۲۶ weeks duration of pregnancy is calculated ۲۷۰.۰۷ days which had no significant relationship with LMP. Conclusion: According to this study parity has no effect on pregnancy duration. Mean pregnancy duration was shorter comapared to Naegele’s rule and Harvard University studies.