amount of progesterone is produced by the corpus luteum to maintain the early pregnancy. Assessment of this situation was traditionally carried out by an endometrial biopsy, however recent studies have not confirmed that such assessment is valid. Studies about the value of progesterone supplementation remain deficient, however, such supplementation is commonly carried out on an empirical basis. Infection Infections are estimated to be responsible for between 0.5 and 5% of cases with recurrent miscarriage. The main suspected pathogens are mycoplasma, ureaplasma, Chlamydia trachomatis, Listeria monocytogenes, and herpes simplex virus. An infectious evaluation may be warranted in people with immunodeficiency, or with signs of chronic endometritis/cervicitis on examination. Otherwise, there is no evidence that routine infectious evaluation is appropriate or productive. Chronic endometritis (CE) due to common bacteria has been found to be prevalent in some women with a history of recurrent miscarriage. One study found that 71 percent of women who tested positive for this condition were successfully treated by an antibiogram-based antibiotic treatment. 78.4 percent of these women subsequently became pregnant in the year following treatment. The study concludes that "CE is frequent in women with recurrent miscarriages," and that "antibiotic treatment seems to be associated with an improved reproductive outcome." The authors also conclude, "that hysteroscopy should be a part of the diagnostic workup of infertile women complaining of unexplained recurrent miscarriage." Despite challenges in diagnosing chronic endometritis, often done by identifying plasma cells within the lining of the womb, a recent study identified women with chronic endometritis were more likely to have a miscarriage than women without. Assessment Transvaginal ultrasonography has become the primary method of assessment of the health of an early pregnancy. In non-pregnant patients who are evaluated for recurrent pregnancy loss the following tests are usually performed. Parental chromosome testing (karyogram) is generally recommended after 2 or 3 pregnancy losses. Blood tests for thrombophilia, ovarian function, thyroid function and diabetes are performed. Treatment If the likely cause of recurrent pregnancy loss can be determined treatment is to be directed accordingly. In pregnant women with a history of recurrent miscarriage, anticoagulants seem to increase the live birth rate among those with antiphospholipid syndrome and perhaps those with congenital thrombophilia but not in those with unexplained recurrent miscarriage. One study found that in many women with chronic endometritis, "fertility was restored after appropriate antibiotic treatment." There are currently no treatments for women with unexplained recurrent pregnancy