What is progesterone? Progesterone is a steroid hormone that plays an important role in the initiation and development of pregnancy. However, it is important not only during pregnancy, but also outside of it, to maintain the function of the sexual organs. During pregnancy, it is produced by the placenta – from the second month, when it takes over the functions of the corpus luteum. The rest of the time, progesterone is produced by the ovaries. During pregnancy, progesterone allows the migration of the fertilized egg to the uterus, then facilitates its implantation, among other things. The level of progesterone in the blood varies during the menstrual cycle. It is low during the follicular phase, rises sharply during the luteal phase, and reaches a maximum 5 to 10 days after the peak of LH, the luteinizing hormone that triggers ovulation. Progesterone levels then decline unless pregnancy has occurred. In the blood, progesterone circulates bound to various proteins – transcortin, albumin and orosomucoid. Why test progesterone levels? Blood progesterone levels can be measured in the following cases: Between the 20th and 23rd days of the menstrual cycle, to ensure that the corpus luteum is producing normal amounts of progesterone necessary for implantation of the fertilized egg; In case of doubt in case of recurrent miscarriages; During the first weeks of pregnancy to ensure that it goes well; To check the effectiveness of ovulation induction in assisted reproduction; To diagnose an ectopic pregnancy, in combination with an analysis of hCG levels, when progesterone is abnormally low; In the case of assisted reproduction – for in vitro fertilization, embryo transfer and for planning intrauterine inseminations. Interpretation of results Sample analysis is performed from venous blood. No specific preparation for the examination is required, but the date of the last menstruation or the beginning of pregnancy must be indicated. Normal blood progesterone levels Follicular phase -0.6-4.7 nmol/L; Ovulation – 2.4 – 9.4 nmol/L; Luteal phase – 5.3 – 86 nmol/L; Menopause – 0.3 – 2.5 nmol/L Changes in Progesterone Levels Progesterone levels decrease during menopause. Progesterone levels during pregnancy: 1st trimester – 35 – 141 nmol/L; 2 trimester – 80 – 264 nmol/L; 3 trimester – 187 – 681 nmol/L; When abnormally low progesterone levels are found, especially in women trying to conceive, supplementation may be considered during the second part of the menstrual cycle. Progesterone can be elevated in several diseases, particularly certain ovarian or adrenal tumors. Low progesterone levels Luteal failure responsible for recurrent abortions or sterility; Low levels found during several consecutive menstrual cycles – anovulatory cycle, luteal phase abnormality with decreased LH and FSH,short cycles with reduced levels of estradiol and FSH; Insufficient secretion of FSH; Ovarian failure; Menopause; Hyperandrogenism; Hyperprolactinemia; Deficiency of enzymes of steroid hormone metabolism – rare hereditary diseases -17a-hydroxylase, 20-22 desmolase High levels of progesterone Pregnancy; Induction of ovulation; Some ovarian tumors that secrete hormones; Some adrenal tumors; Some congenital diseases References: https://www.doctissimo.fr/html/sante/analyses/sa_375_erone.htm https://www.passeportsante.net/fr/Maux/analyses-medicales/Fiche.aspx?doc=analyse- progesterone-sang