391: Duration of labor and maternal and neonatal morbidity

Abstract

To characterize the relationship between duration of active phase labor (APL) and second stage labor (SSL) and maternal and neonatal morbidity. Secondary analysis of Consortium on Safe Labor. From 66,940 non-anomalous, NTSV live births, we excluded deliveries where APL (≥5cm dilation) or SSL durations could not be calculated or were >90th percentile (12h, 4h respectively), and from sites with missing determinants of morbidity. Maternal composite morbidity (MCM: death, hysterectomy, severe lacerations, hemorrhage, fever) and neonatal composite morbidity (NCM: death, HIE, PVH/IVH, ICH, ventilator, seizure, pneumonia, 5m Apgar <4, birth injury, sepsis) were calculated. Adjusted odds ratios for MCM and NCM were estimated by logistic regression for APL and SSL durations when compared to both durations <1h total and durations 1h shorter. 52,923 deliveries remained after exclusions, with median APL and SSL durations of 3h and 1h respectively. In adjusted models, compared to labor durations <1h total, MCM was significantly different across APL (p<0.001) and SSL (p<0.001), and NCM significantly different across SSL (p<0.001), although not APL (p=0.07) (Fig 1A-B, 2A-B, closed circles). These relationships were roughly linear with no apparent inflection point where morbidity increased more rapidly. When compared to labor durations 1 hour shorter, significant differences were also seen in MCM and NCM for SSL (through 4 and 3 hours respectively), although without a linear relationship (Fig 1B, 2B, open circles). Increase in morbidity during APL was not significant when compared to durations 1h shorter (Fig 1A, 2A, open circles). MCM and NCM are higher with longer durations of APL and SSL. No apparent inflection point where morbidity increases more rapidly was identified. Some incremental increases in morbidity noted versus durations < 1h were obscured when comparison was made to labors 1h shorter. Focusing on short increases in duration of labor may miss important underlying trends.View Large Image Figure ViewerDownload Hi-res image Download (PPT)