# Risk factors for postpartum hemorrhage according to the Robson classification in a low-risk maternity hospital

## TL;DR

This study identifies risk factors for postpartum hemorrhage in a low-risk maternity hospital using the Robson classification.

## Contribution

The study provides insights into PPH risk factors specific to Robson classifications 1, 3, 2a, and 4a.

## Key findings

- Robson Classification 2a and 4a had higher PPH rates compared to 1 and 3.
- Labor induction increased PPH risk by 18.8%.
- Forceps delivery and birth weight were the best predictors for PPH in the studied classifications.

## Abstract

To evaluate the risk factors for postpartum hemorrhage (PPH) according to
the Robson Classification in a low-risk maternity hospital.

We conducted retrospective cohort study by analyzing the medical records of
pregnant women attended in a low-risk maternity hospital, during from
November 2019 to November 2021. Variables analyzed were: maternal age, type
of delivery, birth weight, parity, Robson Classification, and causes of PPH.
We compared the occurrence of PPH between pregnant women with spontaneous
(Groups 1 and 3) and with induction of labor (2a and 4a). Chi-square and
Student t-tests were performed. Variables were compared using binary
logistic regression.

There were 11,935 deliveries during the study period. According to Robson’s
Classification, 48.2% were classified as 1 and 3 (Group I: 5,750/11,935) and
26.1% as 2a and 4a (Group II: 3,124/11,935). Group II had higher prevalence
of PPH than Group I (3.5 vs. 2.7%, p=0.028). Labor induction increased the
occurrence of PPH by 18.8% (RR: 1.188, 95% CI: 1.02-1.36, p=0.030). Model
including forceps delivery [x2(3)=10.6, OR: 7.26, 95%CI:
3.32-15.84, R2 Nagelkerke: 0.011, p<0.001] and birth weight
[x2(4)=59.0, OR: 1.001, 95%CI:1.001-1.001, R2
Nagelkerke: 0.033, p<0.001] was the best for predicting PPH in patients
classified as Robson 1, 3, 2a, and 4a. Birth weight was poor predictor of
PPH (area under ROC curve: 0.612, p<0.001, 95%CI: 0.572-0.653).

Robson Classification 2a and 4a showed the highest rates of postpartum
hemorrhage. The model including forceps delivery and birth weight was the
best predictor for postpartum hemorrhage in Robson Classification 1, 3, 2a,
and 4a.