Interventions following routine hemoglobin assessment after vaginal delivery

To assess the utility of routine postpartum hemoglobin (Hgb) testing after vaginal delivery with normal blood loss by evaluating the frequency of blood transfusion and intravenous (IV) iron administration.

This retrospective cohort study included vaginal deliveries with blood loss <500 mL at a tertiary hospital between January 2020 and May 2025. Patients with missing blood loss data, preeclampsia/eclampsia, or a hemorrhage diagnosis were excluded. Predelivery and postpartum Hgb values, as well as blood transfusion and IV iron administration, were collected. The primary outcomes were postpartum blood transfusion and IV iron administration. Univariate logistic regression was used to identify variables associated with blood transfusion and IV iron administration. Multivariable logistic regression was then performed to evaluate independent predictors of each outcome. Manual chart review was performed for those who received a blood transfusion or IV iron to identify signs of anemia and relevant comorbidities.

Of 21,719 vaginal deliveries, 11,180 were included. Of these, 10,075 (90.1%) underwent postpartum Hgb testing with a mean Hgb decrease of 1.3 g/dL (SD, 0.9) pre- to postdelivery. Among the 11,180 deliveries, 19 (0.2%) received blood transfusion, and 82 (0.7%) received IV iron. Higher predelivery Hgb was associated with lower odds of blood transfusion (odds ratio [OR], 0.27; 95% confidence interval [CI], 0.19-0.38) and IV iron administration (OR, 0.25; 95% CI, 0.20-0.30). Among the 10,954 deliveries with predelivery Hgb ≥9 g/dL, six (0.05%) received blood transfusion. Of these six patients, five had anemia symptoms (n = 1) or comorbidities, including sepsis (n = 2) and vaginal hematoma (n = 2). Thirty-nine patients with a predelivery Hgb ≥9 g/dL received IV iron, of whom 13 (33.3%) had anemia symptoms and/or comorbidities. Among patients with predelivery Hgb ≥9 g/dL, normal blood loss, and no symptoms or comorbidities, the probability of receiving a blood transfusion or IV iron was 0.23% (one blood transfusion and 26 IV iron infusions). Applying a predelivery Hgb threshold of ≥9 g/dL to guide selective postpartum testing would have avoided 98% of routine assessments while maintaining 99.8% sensitivity for identifying patients who received a blood transfusion or IV iron.

In this large cohort of vaginal deliveries with normal blood loss, blood transfusion and IV iron administration were rare. Selective postpartum Hgb testing based on predelivery Hgb and symptoms or comorbidities can be considered.