What should be the size of ovum for pregnancy?

For pregnancy to successfully, the size of the ovum is crucial. The ideal size of the ovum for pregnancy should be around 20-25 mm in diameter. This size is considered optimal as it allows for the ovum to be successfully fertilized by the sperm and subsequently develop into a healthy embryo. The precise measurement can slightly vary among different women, but the range of 20-25 mm is generally considered optimal for successful pregnancy.