Sonographic determination of fetal gender in the second and third trimesters in a private hospital in Enugu, southeast Nigeria

Background: Pregnant Nigeria women are usually anxious about the gender of their fetuses for social reasons. Objective: The purpose of this study was to determine the accuracy of ultrasound in the determination of fetal gender in women who wished to know the gender of their fetuses and in those whom the gender of their fetuses were requested for on clinical grounds in the second and third trimesters. Methods: A prospective longitudinal study was performed on 1480 singleton pregnancies who met the inclusion criteria between February 2004 and January 2008. Ultrasound examination was performed on GE ALOKA 500 machine, transabdominally between 14 and 40 weeks gestational age (GA). Both transverse and mid-sagittal planes of a section of the fetal genital tubercle were performed to identify the gender. The subsequent gender at birth was obtained from the hospital birth records. Results: During the study, 1211 (81.8%) women requested gender information while the gender information from 269 (18.2%) women was requested for on clinical grounds. The mean GA at which the fetuses were scanned was 29+2 ± 3+6 weeks (range 14-40 weeks). Fetal gender assignment was possible in 1350 (91.2%) out of 1480 fetuses; 680 assigned male and 670 female. Of these, the fetal gender corroborated birth sex in 1325 (89.5%) and disagreed in 25 (1.7%) cases. The overall estimated sensitivity of the scan is 98.1%, while the estimated specificity for identification of the male sex (100%) was higher than the female (78.3%). Of the 130 cases where no identification of gender was possible, 50 were in the second trimester and 80 were in the third trimester. Conclusion: This study demonstrated that the accuracy of fetal gender determination increased with gestational age, from 97.1% in the second trimester to 98.5% in the third trimester. The overall fetal gender accuracy rate for male fetus was better than female and was statistically significant (P < 0.05).