Diurnal Influence to the Onset of Preterm Delivery

Objective: To analyse the onset of uterine contractions and preterm delivery in order to document any diurnal influence. Methodology: Hospital records of the patients admitted with the diagnosis of preterm labor were retrieved from January 2003 to February 2007 from Sobhraj Maternity Hospital, Karachi. Time of onset of uterine contractions establishment of preterm labor parity and gender of the baby was noted. Data was analyzed by SPSS version 10 for descriptive and inferential statistics. Results: During the study period, 632 preterm deliveries were recorded. Precise timing of onset of uterine contractions was available in 340 (38.33%) deliveries. Uterine contraction leading to labor started from 2:00AM to 5:00AM and 397 babies delivered during the night / early morning (8:00 PM to 8:00 AM) and 235 babies were delivered during day (8:00AM to 8:00PM) [chi2 = 7.908; p= 0.004]. Among all babies delivered during night / early morning 311 (49.2%) were born between 2:00AM to 8:00AM. Conclusion: Preterm labours demonstrate diurnal rhythm. In most of the women, contractions started between 2:00AM 5:00AM and most of the deliveries occurred from 2:00AM 8:00AM.