24 hour rhythm to the onset of preterm labour

Abstract

OBJECTIVE To describe the time of onset of contractions which result in preterm delivery to investigate if there is a diurnal influence.

Design: The admission register for the neonatal unit was used to identify admissions for prematurity over a three-year period. Obstetric case records were then reviewed to obtain the recorded time of onset of contractions when delivery was preceded by spontaneous labour.

Setting: A maternity hospital in the United Kingdom.

Main outcome measures: The time of onset of spontaneous contractions which result in preterm labour and delivery.

Results: Four hundred and twenty-five women in preterm labour were studied. A significant diurnal rhythm in the timing of onset of contractions was noted with 42% of deliveries occurring in labour which commenced between midnight and 0600 hours. Subgroup analysis indicated that there was a significant rhythm in second trimester preterm labours, male and female babies and that this rhythm was present during both the winter and summer months.

Conclusion: The periodicity of preterm labour onset demonstrates a rhythm which is similar to the rhythm in the onset of labour at term. Preterm labour most commonly begins between midnight and 0600 hours.