Pregnancy involves some structural and physiological adjustments to achieve an optimal outcome for the fetus and its mother. The magnitude of these changes is influenced by number of fetuses in utero. This research was designed to compare serum biochemical and ovarian morphometric changes associated with singleton and twin pregnancies in Maradi goats. Using Richardson formula, 2.1 × [CRL (cm) + 17], twelve (12) ovarian and blood samples (7 single and 5 twin) from mid gestation (≈70-100 dGA) pregnant goats were purposively selected. Ovarian weights, ovarian diameters, serum biochemistry and levels of ovarian sex hormones were determined and analyzed using standard procedures. Twin pregnant goats had higher (p < 0.05) left ovarian weights, average ovarian weight, left ovarian diameters, average ovarian diameter, serum calcium and inorganic phosphorus levels compared with singleton pregnant goats. There was no significant variation (p > 0.05) in the mean crown-rump length, mean gestational age, mean fetal weight, right ovarian weights, right ovarian diameters, serum concentrations of sodium, potassium, chloride, urea, creatinine, AST, ALT, total protein, estrogen and progesterone between sinlgeton and twin pregnant Red Maradi goats. Ovarian sections from the twin bearing mid gestation goats had more growing follicles and fewer primordial follicles compared with the singleton bearing goats. Findings from this study indicate that twin pregnancy, which could be genetically programmed, has the tendency to affect ovarian follicles development, ovarian morphometrics and calcium metabolism in mid gestation in Red Maradi goats.