Breech presentation during pregnancy means that the buttocks of the fetus are presenting first at the bottom of the uterus, and the head is in the upper part or fundus of the uterus. The uterus is shaped rather like an upside-down pear, so the baby's head fits in the lower part, with more room at the top for movement of the extremities. As the baby grows, the uterus gets more crowded and it is most common for it to assume the head -down presentation. Generally, the placenta is attached at the side of the uterus, which seems to encourage the head-down presentation, too. There are a number of variations of the breech presentation, determined by the position of the baby's body parts, like arms and legs, in relation to his or her head and trunk. They are -

Frank breech (50-70%) - Hips flexed, knees extended with the feet near the face (pike position)
Complete breech (5-10%) - Hips flexed, knees flexed (cannonball position)
Footling or incomplete (10-30%) - One or both hips extended, foot presenting
Kneeling breech - the baby is in a kneeling position, with one or both legs extended at the hips and flexed at the knees. This is extremely rare.