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Advisor(s)
Abstract(s)
Background High caesarean rates are a matter of concern and the
influence of hospital functioning in such rates has been debated.
Objectives To understand the hourly pattern of deliveries after
spontaneous labour onset, and to compare the trajectories of the mean
number of deliveries on working days with those on weekends,
according to the mode of delivery.
Methods Between April/2005 and August/2006, women (n = 8,495)
delivering a live birth in public hospitals (level III) were consecutively
recruited during the procedure of assembling a birth-cohort in
the North of Portugal. For this purpose we selected those with a
singleton pregnancy and admitted with spontaneous labour
(n = 4,087). For eligible subjects, date, hour and mode of delivery
were collected from medical records. Statistical modeling used unidimensional
cubic splines with hour, ranging from 0 to 23, as
predictor and the mean number of vaginal and caesarean deliveries as
dependent variables. These splines are functions defined on the
domain of the independent variable and that consist of a finite junction
of local cubic polynomial regressions. Fitting and selection of the
models was assessed through the percentage of explained deviance,
generalized cross-validation score and residuals inspection. Comparison
of curves was based on the 95 % pointwise prediction confidence
intervals.
Results The percentage of explained deviance in the models was 85
and 68 % for vaginal and 90 and 51 % for caesarean deliveries, on
working days and weekends, respectively. On working days, a pattern
of relative deficit of nocturnal deliveries with a minimum between 5
a.m. and 6 a.m. was observed for both vaginal and caesarean deliveries.
The hourly variation in diurnal births was different according to
the mode of delivery. Vaginal deliveries steadily increased from 6 a.m. onwards, reaching a peak at 6 p.m. Caesarean deliveries presented two
diurnal peaks; the first at 11 a.m. and the second in the late afternoon,
between 6 p.m. and 7 p.m. The hourly pattern of vaginal deliveries on
weekends and working days was quite similar, but a significant difference
in the mean number of vaginal deliveries was observed
between 10 p.m. and 11 p.m., which is lower on weekends. The peaks
for caesarean deliveries on working days disappeared on weekends,
the only pattern similarity being the decrease observed overnight.
Conclusion There was no evidence of the weekend effect in the mean
number of caesarean deliveries. Nonetheless, the differences observed
in the hourly pattern of vaginal and caesarean deliveries on working
days suggest the influence of hospital functioning in the time when
caesarean is performed.
Description
Keywords
Mode of delivery Hour of birth
Citation
Teixeira, Cristina; Gaio, Rita; Costa, Joaquim; Barros, Henrique (2012). Timing of birth and mode of delivery after spontaneous labour onset. In The IEA-EEF European Congress of Epidemiology 2012: Epidemiology for a Fair and Healthy Society. Porto. ISSN 0393-2990. p. s52-s52
Publisher
Springer - European Journal of Epidemiology