The Influence of Threatened Miscarriage on Pregnancy Outcomes: A Retrospective Cohort Study in a Nigerian Tertiary Hospital

Background: Pregnancies complicated by threatened miscarriage (TM) may be associated with adverse pregnancy outcomes. The objective of this study was to compare the differences in pregnancy outcomes between the women who experienced TM and asymptomatic controls. Methods: This was a 10-year retrospective review. Case records of 117 women who were managed for TM from January 1, 2010, to December 31, 2019, were retrieved and studied. The control group was developed from an equal number of asymptomatic clients matched for age, parity, and BMI who were receiving antenatal care (ANC) during the same period. Data on demography, clinical and ultrasound findings, treatment, and pregnancy outcomes were retrieved and analyzed. Results: Spontaneous abortion rate of 13.7% was recorded among the study group compared with 3.4% in the control (P-value [p] = 0.005, odds ratio [OR]: 4.475; 95% confidence interval [CI]: 1.445 - 13.827). Women with TM had higher odds for placenta previa (p = 0.049, OR: 4.77, 95% CI: 2.19 - 23.04), premature rupture of membranes (PROM) (p = 0.028, OR: 1.918, 95% CI: 1.419 - 2.592), postpartum hemorrhage (PPH) (p = 0.001, OR: 2.66, 95% CI: 20.8 - 8.94), and preterm birth (OR: 2.5, 95% CI: 1.75 - 3.65). They were also more likely to undergo cesarean section (p = 0.020, OR: 1.70, 95% CI: 1.053 - 2.964). There was no statistically significant difference in their infants’ mean birth weight (3.113 ± 0.585kg for the TM group and 3.285± 0.536kg for the control, P=0.074). Other maternal and perinatal complications were similar. Admission for bed rest significantly improved fetal survival. Women who were not admitted for bed rest had higher odds of pregnancy loss (OR: 3.443, 95% CI: 1.701-7.99). Other treatment plans did not significantly contribute to a positive outcome. Conclusion: Threatened miscarriage is a significant threat to fetal survival and may increase the risk for operative delivery. Bed rest improves the live birth rate.