Prospective Estimation of Duration of Pregnancy in Women Attending Antenatal Care at the University of Nigeria Teaching Hospital, Enugu, Nigeria

Background: Accurate estimation of gestational age is of paramount importance in obstetric care. The most commonly used principle for determining gestational age and duration of pregnancy is Naegele’s rule, which is supplemented by ultrasound estimation of gestational age.
Aim: This study was to assess the accuracy of Naegele’s rule in pregnancy and comparison with ultrasound biometry.
Study Design: Hospital based prospective study.
Place and Duration of Study: Department of Obstetrics and Gynaecology University of Nigeria Teaching Hospital (UNTH), Enugu, Nigeria: a 2-year study.
Methods: This was a prospective study of pregnant women selected at random with normal 28day cycle, who knew their last menstrual period (LMP) and were delivered in the labour ward of the UNTH Enugu, Nigeria between January 1, 2007 and December 31, 2008. The total number of respondents studied was 326 women. The respondents were divided into 2 groups: 163 for each group. Group A were those whose estimated date of delivery was based on Naegele’s rule and group B were those whose expected date of delivery (EDD) was based on ultrasound (USS). Data was analyzed with SPSS Version 15.0 (SPSS Inc. Chicago, IL, USA), using Chi-square and T-test. The significant level was taken if P < 0.05 at 95% Confidence level.
Results: The mean age of the population was 29.8years. The mean duration of pregnancy for the two groups was 280 days. There was no statistical difference between the two groups in the age of the respondents p=0.832. There was no statistical difference also between the two groups in the parity of the respondents p=0.894.
The gestational age (GA) at delivery for DLMP was 280 days with (standard deviation [SD] 8.3 days) while the GA at delivery for DUSS was 280 days with SD 7.9 days.
Conclusion: The duration of 280days instead of 282days appears more applicable in our environment.