<p>Progesterone is a hormone that occurs naturally in females, and is essential for endometrial receptivity, embryo implantation, and the successful establishment of pregnancy. A low progesterone concentration or an insufficient response to progesterone can cause infertility and pregnancy loss <sup class="text-reference-group"><a class="reference-popover-link" data-content="Young SL, Lessey BA: Progesterone function in human endometrium: clinical perspectives. Semin Reprod Med. 2010 Jan;28(1):5-16. doi: 10.1055/s-0029-1242988. Epub 2010 Jan 26. (PubMed ID 20104424)" href="#reference-A175609">7</a></sup>. Progesterone is used in various contraceptive preparations to prevent ovulation and fertilization <sup class="text-reference-group"><a class="reference-popover-link" data-content="Danielle B. Cooper; Rotimi Adigun (2018). Oral contraceptives. StatPearls Publishing." href="#reference-T481">15</a></sup>, <sup class="text-reference-group"><a class="reference-popover-link" data-content="Lopez LM, Ramesh S, Chen M, Edelman A, Otterness C, Trussell J, Helmerhorst FM: Progestin-only contraceptives: effects on weight. Cochrane Database Syst Rev. 2016 Aug 28;(8):CD008815. doi: 10.1002/14651858.CD008815.pub4. (PubMed ID 27567593)" href="#reference-A175612">8</a></sup> as well as in other formulations to promote and support pregnancy. Please see <a href="https://go.drugbank.com/drugs/DB00603">Medroxyprogesterone acetate</a>, <a href="https://go.drugbank.com/drugs/DB00351">Megestrol acetate</a>, <a href="https://go.drugbank.com/drugs/DB00378">Dydrogesterone</a> and <a href="https://go.drugbank.com/drugs/DB14570">Hydroxyprogesterone</a> entries for information on various other forms of progesterone.</p><p>Pharmaceutical progesterone is made from a plant source as a starting material and is chemically identical to progesterone of human ovarian origin <sup class="text-reference-group"><a class="reference-popover-link" data-content="Official drug label" href="#label-reference">Label</a></sup>. Progesterone is available in gelatinized capsule form, vaginal gel form, tablet form, vaginal insert form, and injection form, all used for various purposes <sup class="text-reference-group"><a class="reference-popover-link" data-content="Official drug label" href="#label-reference">Label</a>,<a class="reference-popover-link" data-content="Progesterone gel: Crinone® 4% and Crinone® 8%" href="#reference-F3898">20</a>,<a class="reference-popover-link" data-content="Norethindrone FDA label" href="#reference-F3904">22</a>,<a class="reference-popover-link" data-content="Endometrin FDA label, vaginal insert" href="#reference-F3901">21</a>,<a class="reference-popover-link" data-content="Progesterone injection, FDA label" href="#reference-F3907">23</a></sup>.</p>