title: Miscarriage risk for asymptomatic women after a normal first-trimester prenatal visit.
abstract: OBJECTIVE
  To estimate the risk of miscarriage among asymptomatic women after a prenatal visit between 6 and 11 weeks of gestation where proof of fetal viability of a singleton was obtained by office ultrasonography at the same visit.
  
  
  METHODS
  This was a prospective cohort study performed over 2 years (March 2004-2006) at an antenatal clinic at a large tertiary hospital in Victoria, Australia. Those recruited were 697 asymptomatic women who attended their first antenatal visit between 6 (+2 days) and 11(+6 days) weeks of gestation, where evidence of fetal cardiac activity of a singleton was obtained by office ultrasonography. The main outcome measure was rates of miscarriage, stratified by gestation at presentation.
  
  
  RESULTS
  One case was lost to follow-up. The risk of miscarriage among the entire cohort was 11 of 696 (1.6%). The risk fell rapidly with advancing gestation; 9.4% at 6 (completed) weeks of gestation, 4.2% at 7 weeks, 1.5% at 8 weeks, 0.5% at 9 weeks and 0.7% at 10 weeks (chi(2); test for trend P=.001). Most who miscarried received their ultrasound diagnoses many weeks after their visit; five (45%) were diagnosed in the second trimester, and all but one received their ultrasound diagnoses after 10 weeks of gestation.
  
  
  CONCLUSIONS
  For women without symptoms, the risk of miscarriage after attending a first antenatal visit between 6 and 11 weeks is low (1.6% or less), especially if they present at 8 weeks of gestation and beyond. Our data could be used to reassure such women that the probability of progressing to later than 20 weeks of gestation is very good.
authors.affiliation: University Department of Obstetrics and Gynaecology, Mercy Hospital for Women, Victoria, Australia. stephentong1@gmail.com
authors.forename: Stephen
authors.initials: S
authors.lastname: Tong
authors.forename: Anupinder
authors.initials: A
authors.lastname: Kaur
authors.forename: Susan P
authors.initials: SP
authors.lastname: Walker
authors.forename: Valerie
authors.initials: V
authors.lastname: Bryant
authors.forename: Joseph L
authors.initials: JL
authors.lastname: Onwude
authors.forename: Michael
authors.initials: M
authors.lastname: Permezel
mesh_terms: D000022:Abortion, Spontaneous; D000328:Adult; D005260:Female; D005865:Gestational Age; D006801:Humans; D010298:Parity; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011295:Prenatal Care; D012306:Risk