Vaginal Bleeding during Pregnancy and Preterm Birth

Abstract

This study investigated the relation between self-reported vaginal bleeding during pregnancy and preterm birth in a prospective cohort of 2,829 pregnant women enrolled from prenatal clinics between 1995 and 2000 in central North Carolina. The overall association between vaginal bleeding and preterm birth was modest (risk ratio (RR) = 1.3, 95% confidence interval (CI): 1.1, 1.6). Bleeding in the first trimester only was associated with earlier preterm birth (< or =34 weeks' gestation) (RR = 1.6, 95% CI: 1.1, 2.4) and preterm birth due to preterm premature rupture of the membranes (PPROM) (RR = 1.9, 95% CI: 1.1, 3.3). Bleeding in both trimesters was associated with preterm birth due to preterm labor (RR = 3.6, 95% CI: 1.9, 6.8). Bleeding of multiple episodes, on multiple days, and with more total blood loss was associated with an approximate twofold increased risk of earlier preterm birth, PPROM, and preterm labor. In contrast, bleeding in the second trimester only, of a single episode, on a single day, and with less total blood loss was not associated with any category of preterm birth. Vaginal bleeding was not associated with preterm birth among African Amercians (RR = 1.2, 95% CI: 0.9, 1.7). This study indicates that more intense but not less intense bleeding is associated with earlier preterm birth and spontaneous preterm birth presenting as PPROM or preterm labor, and it suggests that bleeding is less predictive of preterm birth among African-American compared with White women.

Indications for, Timing of, and Modes of Delivery in a National Cohort of Women Admitted With Antepartum Hemorrhage at 22+0 to 28+6 Weeks’ Gestation

“…Yang et al found that of 683 women enrolled in a prospective study who reported vaginal bleeding in the first or second trimester, half delivered at less than 36 weeks. 13 Women experiencing bleeding had a 17.3% rate of prior preterm birth, similar to our 21% rate, but the authors did not report causes of bleeding or hospitalization rate, and they excluded multiple gestations. 13 Bleeding was documented by telephone interview only.…”

“…13 Women experiencing bleeding had a 17.3% rate of prior preterm birth, similar to our 21% rate, but the authors did not report causes of bleeding or hospitalization rate, and they excluded multiple gestations. 13 Bleeding was documented by telephone interview only. 13 In another cohort of women in the United States, only 10 of 92 women with second trimester bleeding delivered between 34 and 36 weeks, and four delivered at less than 34 weeks.…”

“…10 Many studies report increased rates of preterm birth in women with vaginal bleeding during pregnancy (OR 1.3 to 3.17). 2,5,9,13,28 In the CPN cohort, the rate of preterm birth at less than 37 weeks was75%, much higher than the 8% overall rate for Canadian births. 29 This reflects the high risks associated with pregnancies requiring admission to tertiary care centres with APH in the second trimester.…”

“…13 Bleeding was documented by telephone interview only. 13 In another cohort of women in the United States, only 10 of 92 women with second trimester bleeding delivered between 34 and 36 weeks, and four delivered at less than 34 weeks. 2 This study used an outpatient population base and excluded stillbirths at less than 28 weeks and multiple pregnancies.…”

“…1 Increased risks for infants born to women with vaginal bleeding in pregnancy include preterm delivery, growth restriction and low birth weight, congenital malformations, and stillbirth and perinatal mortality. 4,5,7,[9][10][11][12][13][14] Although maternal mortality is rare, morbidity may include hemorrhage and a need for blood transfusion, surgery, hospitalization, or intensive care. 10,12,15,16 Despite this, maternal outcomes are infrequently reported.…”