Prolonged labour attributed to large fetus.

The aim of this study is to assess the interactive dynamics of power, passenger and passage in relation to an adverse course of labour. The design was a community-based follow-up of all women with singleton pregnancies experiencing spontaneous term labour. Median of first stage was 2.6 h for multiparas and 3.7 h for primiparas. Median of second stage was 20 min for multiparas and 91 min for primiparas. Heavy birth weight significantly influenced a prolonged late first stage OR 6.6 (CI 2.1-21) and second stage of labour OR 4. 5 (CI 1.5-14) among primiparas. The attributable proportions of heavy birth weight for prolonged labour were 19-21%. Large paediatric head circumference showed a positive correlation to prolonged late first stage OR 3.2 (CI 1.2-9) and intervention OR 7.2 (CI 1.8-35), with an attributable proportion of 22%. For multiparas no significant association were found. To conclude, this study indicates that heavy birth weight and large head circumference contribute to 1/5th of the prolongation of labour and interventions among primiparas. Copyright 2000 S. Karger AG, Basel