Category: Clinical Obstetrics
Poster Session I
In recent years, thresholds for duration during first stage of labor have been up for debate. New evidence indicates that labor can last longer than previously considered safe and still result in healthy infants. A prolonged second stage of labor increases the risk of postpartum hemorrhage (PPH). However, recent studies suggest that second stage duration should be modelled as an intermediate on the pathway between first stage labor duration and adverse outcomes. We therefore set out to investigate the relationship between first stage duration, second stage duration and PPH.
Study Design:
A population-based cohort study including 44,151 nulliparous, singleton, term, vertex deliveries with spontaneous labor onset in Stockholm/Gotland (2008-2020). Deliveries with missing data on the onset or end of first stage or total blood loss were excluded. First stage duration was defined as the time interval (h) from 5 to 10 cm cervical dilation and second stage as the time from 10 cm to birth. The outcome was total blood loss (ml) and blood loss > 1000 ml (Swedish definition of PPH). Quantile regression and restricted cubic splines were used to estimate associations between first stage duration and blood loss. Modified Poisson regression was used to calculate risk ratios for the association between first stage duration and PPH.
Results:
The median blood loss volume increased with duration of first stage, in a linear fashion, after 10 hours (Fig 1). The proportion of PPH was highest (31.5%) among women with a long first stage (≥ 12 h) and a long second stage of labor (≥ 5 h) while the proportion was lowest (7.3%) for women with a short first ( < 8 h) and a short second stage of labor ( < 3 h; Fig 2). The adjusted risk ratio for PPH in deliveries with first stage ≥ 12 hours compared to first stage < 8 hours was 1.6 (95% CI:1.5-1.8).
Conclusion:
The risk of PPH was increased with longer first stage of labor duration. There was a linear association between duration of first stage and total blood loss after 10 hours of labor. Proportions of PPH were highest among women with a long first and second stage of labor.
Linnea V. Ladfors, MD (she/her/hers)
PhD student
Clinical Epidemiology Division, Department of Medicine, Solna, Karolinska Institutet
Stockholm, Sweden, Sweden
Xingrong Liu, PhD
Clinical Epidemiology Division, Department of Medicine, Solna, Karolinska Institutet
Stockholm, Sweden, Sweden
Anna Sandström, MD, PhD
Clinical Epidemiology Division, Department of Medicine, Solna, Karolinska Institutet
Stockholm, Sweden, Sweden
Louise Lundborg, CNM, PhD
Clinical Epidemiology Division, Department of Medicine, Solna, Karolinska Institutet
Stockholm, Sweden, Sweden
Jonathan M. Snowden, PhD
Oregon Health and Science University
Portland, Oregon, United States
Mia Ahlberg, CNM, PhD
Clinical Epidemiology Division, Department of Medicine, Solna, Karolinska Institutet
Stockholm, Sweden, Sweden
Olof Stephansson, MD, PhD
Department of Medicine Solna Clinical Epidemiology Division Karolinska Institute
Stockholm, Sweden, Sweden