A bicornuate uterus is congenital, meaning you were born with it. The fetal uterus develops while in it's still in the uterus — sometime between 10 and 20 weeks of pregnancy. During development, two ducts (called the Mullerian ducts) normally fuse together to form one uterine cavity. In the case of a bicornuate uterus, two uterine cavities exist because the ducts did not merge together completely. A bicornuate uterus can have a deep heart shape or it can be minor and never cause a problem. A heart-shaped uterus is not hereditary — meaning you won’t pass it on to your children.