According to the Office on Women's Health, unborn babies usually turn into a head-down position by the end of week 36 of the pregnancy. Some babies do not turn until the end of week 37.
As a woman nears the end of her pregnancy term, the fetus turns head down to prepare for the birthing process. Around this same time, lightening will occur. Lightening is when the baby drops into the lower part of the uterus in the mother's pelvic area. According to American Pregnancy, approximately one in 25 births have breech presentations, which means the baby's back, buttocks, feet or any part of the body other than the head presents first. If a baby is in the breech position, the physician can attempt to turn the baby to the head-down position to prevent complications.