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Günther Heller a Institute of Medical Sociology and Social
Medicine, Medical Centre of Methodology and Health Research,
Philipps-University of Marburg, Medical School, D 35033 Marburg,
Germany, b Department of Obstetrics, Centre of Gynaecology and
Obstetrics, Philipps-University of Marburg, c Institute of
Quality Assurance Hesse, D 65760 Eschborn, Germany
Correspondence
to: G Heller hellerg{at}mailer.uni-marburg.de
A higher neonatal mortality related to intrapartum events
during the night has been reported in Great Britain.
1 2
We investigated whether the time of birth affects early neonatal mortality or deaths related to asphyxia in low risk births.
Data from the perinatal birth register of the federal state of
Hesse, Germany, 1990-8, were used (www.med-qs-hessen.de). The register
comprises detailed information about all infants born in birth clinics
(more than 95% of all births in Hesse); about the mother, including
the pregnancy; and about the delivery, as documented by the
obstetrician in charge of the birth, using an evaluated standardised
questionnaire comprising 67 items.3 Detailed information
is available about the child's morbidity and reasons for death coded
in 40 predefined categories adapted from ICD-9 (international
classification of diseases, 9th revision).
Outcome events were deaths during labour or within the first seven days
of life (early neonatal deaths) and asphyxia related deaths during the
same period. Completeness of the record of all early neonatal deaths
was validated by comparison with corresponding death rates as reported
by the statistical office of Hesse.4
To control for the effects of planned births with respect to the time
of birth we excluded antepartum deaths, caesarean sections, infants
born before the 37th week of gestation, and infants with congenital
malformations or hereditary metabolic diseases. Those births occurring
between 9 pm and 6 59 am were defined as night time births. Otherwise
births were assumed to have taken place during the day.
Relative risks and 95% confidence intervals were calculated to assess
the effect of night and day on death rates. A total of 380 930 births
met the criteria for inclusion. Fifty seven early neonatal deaths were
observed, reflecting the low mortality risk of these selected births.
Babies born at night were almost twice as likely to die as babies born
during the day (relative risk=1.86; 95% confidence interval 1.10 to
3.13). For deaths related to asphyxia an even more pronounced relation
was observed (3.89; 1.51 to 10.03; table).
Our results confirm a higher early neonatal mortality in low risk
babies born at night. This may be a result of staff's increased physical and mental fatigue during the night, when doctors in charge,
at least in Germany, have usually worked through a complete day shift.
Overreliance on less experienced staff may be another important reason
for the higher risk of early neonatal death during the night. These
phenomena are not specific to the NHS or the British population. Better
designed shifts, resulting in shorter working hours or decreased
workload with greater supervision by experienced staff at night, should
be considered to reduce early neonatal mortality during the night.
Although our analyses are consistent with previously reported British
results, some differences should be considered.
1 2
We
used slightly different definitions of night and day because the hours
of day shifts are different in Germany. Applying the time
categorisation of the British studies yielded almost identical results.
Because of the nature of our database only deaths occurring during
labour or in the first seven days of life could be traced. There was
some concern that babies born during the day are more likely to be
preterm or high risk babies who have had induced births. We therefore
restricted our study population rigorously. The assumption that a death
was related to asphyxia relied solely on the obstetrician's
documentation of morbidity and reasons for death, which could be prone
to error. Nevertheless, a higher early neonatal mortality in general
and a higher mortality related to asphyxia were seen. Additionally, for
each deceased child each author reviewed all the information available
from the register's database for other potential confounding factors.
No alternative explanations for the reported relationship were found.
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Acknowledgments |
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We thank Christiane Gasse for revising the manuscript and helpful comments.
Contributors: GH had the idea for the paper, performed statistical analysis, wrote the paper, and is the study guarantor. BM gave access to data, participated in performing statistical analysis, and commented on the draft. SS helped to write the paper. All authors reviewed the database for each deceased child.
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Footnotes |
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Funding: None.
Competing interests: None declared.
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References |
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| 1. |
Stewart JH, Andrews J, Cartlidge PHT.
Numbers of deaths related to intrapartum asphyxia and timing of birth in all Wales perinatal survey, 1993-5.
BMJ
1998;
316:
657-660 |
| 2. |
Chalmers JWT, Shanks E, Paterson S, McInneny K, Baird D, Penney G.
Scottish data on intrapartum related deaths are in same direction as Welsh data.
BMJ
1998;
317:
539 |
| 3. |
Künzel W.
The birth survey in Germany education and quality control in perinatology.
Eur J Obstet Gynecol Reprod Biol
1994;
54:
13-20[CrossRef][Medline].
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| 4. | Hofacker G. Säuglingssterblichkeit 1998. Staat und Wirtschaft in Hessen 1999; 11: 326-329. |
(Accepted 17 April 2000)
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