Improving the Accuracy of Pregnancy Detection in Balb/C Mice: Innovation in Animal Model Pregnancy Research Application

Accurate detection of pregnancy in BALB/c mice is crucial for ensuring efficiency and reproducibility in biomedical research. Standard methods, such as vaginal plug examination, ultrasonography, and weight monitoring, often exhibit limited sensitivity and specificity. This study aimed to evaluate and compare various methods for detecting pregnancy to establish a more reliable and precise strategy for determining pregnancy status in mice. The study involved 40 BALB/c mice (30 females and 10 males) with a mating ratio of 3:1. The mice were mated and monitored for signs of pregnancy using vaginal swabs, ultrasound, and weight gain assessments. The examinations were repeated from the first day to the 20th day of pregnancy. Data were analyzed using descriptive statistical tests, the Shapiro-Wilk normality test, and Spearman and Kendall correlation tests to assess the relationship between variables. The results indicated that the vaginal swab method had an Area Under Curve (AUC) of 0.87, suggesting a reasonably good ability to differentiate between pregnant and non-pregnant mice. In contrast, weight gain and ultrasound methods demonstrated higher accuracy, with AUC values exceeding 0.95. A significant correlation was found between weight gain and the number of fetuses (r = 0.44), while premarital weight showed a negative correlation with the number of fetuses (r = -0.34). Overall, weight gain, ultrasound, and vaginal swabs are effective methods for detecting pregnancy in BALB/c mice. Combining these techniques could enhance the accuracy of pregnancy detection and reduce error rates in biomedical research. Further studies are recommended to develop more efficient and accessible techniques for pregnancy detection in research settings.