الفهرس 
صفحة العنوانOnly 14 pages are availabe for public view
 |  | from | 131 |  |  |
| | | from | 131 | | |
Abstract
Introduction
Labor is a physiological process, but it is often associated with morbidity and mortality, with the most common cause being blood loss (Roy et al., 2016). The majorities of these mortalities are caused by complications during the third stage of labor, and most commonly are from uterine atony and postpartum hemorrhage (Westhoff et al., 2013).
During third stage of labor that lasts for 10 to 45 minutes after birth of the baby, the uterus continues to contract to a smaller and smaller size, which causes a shearing effect between the walls of the uterus and the placenta, thus separating the placenta from its implantation site. Separation of the placenta opens the placental sinuses and causes bleeding.
The amount of bleeding is limited to an average of 350 milliliters by the following mechanism: The smooth muscle fibers of the uterine musculature are arranged in figures of eight around the blood vessels as the vessels pass through the uterine wall. Therefore, contraction of the uterus after delivery of the baby constricts the vessels that had previously supplied blood to the placenta. In addition, it is believed that