Discrimination by parity is a prerequisite for assessing induction of labour outcome - cross-sectional study.

Background: To demonstrate that studies on induction of labour should be analyzed by parity as there is a significant difference in the labour outcome among induced nulliparous and multiparous women.

Methods: Obstetric outcome, specifically caesarean section rates, among induced term nulliparous and multiparous women without a previous caesarean section were analyzed in this cross-sectional study using the Robson 10 group classification for the year 2016.

Results: In the total number of 8851 women delivered in 2016, the caesarean section rates among nulliparous women in spontaneous and induced labour, Robson groups 1 and 2A, were 7.84% (151/1925) and 32.63% (437/1339) respectively and among multiparous (excluding those women with a previous caesarean section), Robson group 3 and 4A were 1%(24/2389) and 4.37% (44/1005), respectively. Pre labour caesarean rates for nulliparous and multiparous women, Robson groups 2B and 4B (Robson M, Fetal Matern Med Rev, 12; 23-39, 2001) were 3.91% (133/3397) and 2.86% (100/3494), of the respective single cephalic cohort at term.

Conclusions: The data suggests that studies on induction of labour should be analyzed by parity as there is a significant difference between nulliparous and multiparous women.