title: Spontaneous pregnancy reaches viability after low first trimester serum progesterone: a case report.
abstract: BACKGROUND
  Progesterone is produced by the corpus luteum until completion of the luteal-placental shift at approximately 6-10 weeks following last menstruation. Studies have shown that first trimester progesterone levels are predictive of pregnancy viability, and some authors support a level of 5 ng/mL as an absolute threshold to indicate viability.
  
  
  METHODS
  A 47-year-old woman with recurrent pregnancy loss was noted to have a very low first trimester progesterone level (1.2 ng/mL), but the pregnancy progressed to viability. She unfortunately delivered an intrauterine fetal demise at 27 weeks and 3 days' gestation.
  
  
  CONCLUSIONS
  A single serum progesterone level of < 5 ng/mL is suggestive, but not diagnostic, of a nonviable pregnancy. Routine uterine curettage during the evaluation of a pregnancy of unknown location using this level as an absolute cutoff may result in the interruption of a desired, viable pregnancy.
authors.affiliation: Division of Reproductive Endocrinology and Fertility, Duke University Hospital, Durham, North Carolina, USA. john.crochet@duke.edu
authors.forename: John R
authors.initials: JR
authors.lastname: Crochet
authors.forename: Mary C
authors.initials: MC
authors.lastname: Peavey
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Price
authors.forename: Millie A
authors.initials: MA
authors.lastname: Behera
mesh_terms: D005260:Female; D005328:Fetal Viability; D006801:Humans; D008875:Middle Aged; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011296:Prenatal Diagnosis; D011374:Progesterone / Q000097:blood*
chemical_list: D011374:Progesterone