The aims of the current study are to build an equation to predict gestational age (GA) and to compare ultrasound parameters indicative of delivery in healthy English Bulldog bitches subjected to elective cesarean section. Sixteen pregnant female dogs were included in the study. Inner chorionic cavity (ICCDD) and biparietal (BPD) diameters were measured at 30 and 50 days after artificial insemination, respectively, to estimate GA at embryonic and fetal stages. BPD, heart rate (HR), and intestinal peristalsis were measured at 48 h, 24 h, and 6 hours before delivery to compare fetal development. ICCD and BPD values were subjected to linear regression and parameters predictive of elective cesarean section were compared through Student’s t-test before delivery. The number of conceptuses did not influence pregnancy duration. Both ICCD and BPD were significantly correlated to GA; their formulas presented accuracy of ± 1 and ± 2 days, respectively, in comparison to that of progesterone dosage. Based on the comparative ultrasound assessment, BPD has significantly increased from 48 h to 6 h before delivery (≥3 cm), regardless of the number of pups, whereas HR has significantly decreased within 6 h before delivery (HR <200 bpm). There was not statistically significant difference in parameter “intestinal peristalsis” among measurement times. The current study is pioneer in highlighting that measuring ICCD and BPD in the formula is a useful tool to predict GA in the herein investigated breed and that fetal parameters such as BPD and HR are fetal maturity predictors.