threatened abortion: a risk factor for poor pregnancy outcome

the scientific literature regarding threatened abortion is relatively limited on the subject of outcomes and viability at term. to investigate prospectively the risk of adverse pregnancy outcome in women presenting with first-trimester threatened miscarriage, a prospective case control study was performed on 600 subjects, 150 women presenting with bleeding in the first trimester and 450 asymptomatic age-matched controls. main outcome measures included gestational age and weight at delivery as well as incidence of adverse pregnancy outcome such as preterm labor, preterm prelabor rupture of membranes (pprom), placental abruption, and low birth weight (lbw). the first-trimester miscarriage rate in the threatened miscarriage group was 42.7%. compared with controls, women presenting with threatened miscarriage were more likely to deliver prematurely, 14.7% compared with 52.9%, respectively (relative risk 3.6, 95% confidence interval [ci] 2.4-4.8). they were also more likely to have pprom, 6.4% compared with 27.5%, respectively (relative risk 4.2, 95% ci 2.6-6.9) and placental abruption, 5.7% compared with 1.5% respectively (relative risk 3.6, 95% ci 1.2-11.3), and lbw, 14.9% compared with 7.1% respectively (relative risk 2.1, 95% ci 1.1-3.8), low lying placenta 1.1% compared with 18.2% respectively, birth weight 2866 ± 523.3 g compared with 312.45± 591.4 respectively, gestational age 35.71 ± 4.3 compared with 38.07 ± 3.2 respectively. first-trimester vaginal bleeding is an independent risk factor for adverse obstetric outcome and this risk factor should be taken into consideration when deciding upon antenatal surveillance and management of their pregnancies.