Main findings
This systematic review demonstrated a wide variation in reported outcomes and outcome measures in most studies investigating planned mode of birth. 63 prospective studies including data from 6,397,310 women were include. 79% of the studies reported a primary outcome. Among the reported outcomes, maternal outcomes were the most reported ones (47%), followed by childhood long-term outcomes (20%), neonatal short-term outcomes (16.4%), maternal long-term outcomes (14.6%) and subsequent pregnancy outcomes (1.8%) (Table 2). This variation in outcome reporting could be due to differences in ease of data collection for long-term outcomes compared to short-term outcomes for maternal health, whereas for neonatal outcome, immediate outcomes may be more easily collected than to follow-up with children’s long-term health. Only one subsequent pregnancy outcome was recorded but this could be due to the nature of this systematic review that only studies comparing planned CS versus planned VD were included rather than studies comparing first and second pregnancy. The variation in outcome reporting and outcome measures means that individual studies cannot be compared and combined in a meta-analysis of outcomes of planned mode of birth, thereby limiting its usefulness to inform clinical practice.