Causes of Death and Associated Conditions (Codac) - A Utilitarian Approach to the Classification of Perinatal Deaths

J Frederik Frøen; Halit Pinar; Vicki Flenady; Safiah Bahrin; Adrian Charles; Lawrence Chauke; Katie Day; Charles W Duke; Fabio Facchinetti; Ruth C Fretts; Glenn Gardener; Kristen Gilshenan; Sanne J Gordijn; Adrienne Gordon; Grace Guyon; Catherine Harrison; Rachel Koshy; Robert C Pattinson; Karin Petersson; Laurie Russell; Eli Saastad; Gordon CS Smith; Rozbeh Torabi

Disclosures

BMC Womens Health

Abstract

A carefully classified dataset of perinatal mortality will retain the most significant information on the causes of death. Such information is needed for health care policy development, surveillance and international comparisons, clinical services and research. For comparability purposes, we propose a classification system that could serve all these needs, and be applicable in both developing and developed countries. It is developed to adhere to basic concepts of underlying cause in the International Classification of Diseases (ICD), although gaps in ICD prevent classification of perinatal deaths solely on existing ICD codes.
We tested the Causes of Death and Associated Conditions (Codac) classification for perinatal deaths in seven populations, including two developing country settings. We identified areas of potential improvements in the ability to retain existing information, ease of use and inter-rater agreement. After revisions to address these issues we propose Version II of Codac with detailed coding instructions.
The ten main categories of Codac consist of three key contributors to global perinatal mortality (intrapartum events, infections and congenital anomalies), two crucial aspects of perinatal mortality (unknown causes of death and termination of pregnancy), a clear distinction of conditions relevant only to the neonatal period and the remaining conditions are arranged in the four anatomical compartments (fetal, cord, placental and maternal).
For more detail there are 94 subcategories, further specified in 577 categories in the full version. Codac is designed to accommodate both the main cause of death as well as two associated conditions. We suggest reporting not only the main cause of death, but also the associated relevant conditions so that scenarios of combined conditions and events are captured.
The appropriately applied Codac system promises to better manage information on causes of perinatal deaths, the conditions associated with them, and the most common clinical scenarios for future study and comparisons.

Background

A Classification and Its Purpose

Classification is described as a passive construct systematically arranging similar entities with established criteria or differing characteristics.^[1,2] The purpose of classification, however, is information management: including information capture, storage, and retrieval. Classification of perinatal deaths is thus primarily the systematic arrangement of deaths in categories based on information known about them to aid in the process of information management.

This information is vital for many purposes, including health care policy development, surveillance and international comparisons, clinical services and research, and it is crucial that a classification is useful for all these aims. Incompatible classifications for pathologists, obstetricians and researchers, hinder the efforts to improve the value and quality of perinatal pathology services, obstetric health care and research. All need answers as to why deaths occur, but the level of detail required differs. While 98% of perinatal deaths occur in developing countries,^[3,4] most research on prevention takes place in developed countries. To avoid widening the knowledge gap, a classification should be useful for all populations. In a global setting with almost 50 million unregistered live newborns and even less reporting of stillbirths, there is currently insufficient data collected on causes of death either to guide stillbirth prevention programs or to provide accountability and evidence of effect of such programs.^[5] There is a need to scale up efforts to collect data on causes of death in stillbirths in developing countries. No classification system compensates for missing data and misclassifications biased towards the most easily observable conditions that may not be related to the cause of death.

A viable classification system of perinatal deaths that can be applied to existing health information systems should incorporate, or at least relate conceptually, to the International Classification of Diseases (ICD) system, serving as an information management tool for registered conditions. Identifying the underlying cause is the key concept in the cause of death (COD) in ICD,^[6] and a classification system must accomplish this goal as well as retain information on non-lethal conditions representing significant associated conditions. Yet, in classifying perinatal deaths, in particular stillbirths, the ICD has shortcomings. By not consistently identifying the fetus (with its cord, placenta and membranes) as an individual entity to assign codes to, there are many missing codes e.g. for the many significant placental lesions. Thus, a comprehensive classification system cannot be based on converting ICD codes alone, but must supplement ICD and serve to inform steps towards the expected revision of ICD in 2013.

The value of a classification system is not based solely on its simplicity, stringently defined and segregated categories, or inter-rater agreement and reproducibility alone. This would favor classifications that include as little information as possible. A utilitarian approach to classification would identify most clinically distinct categories of deaths, providing simplicity and reproducibility in its basic categories yet retaining important detail by extensive subcategorization or layers.

Selecting the Right Information

A classification system will most consistently provide the results it was designed for, and most systems are designed to identify a few specific groups of interest. Accordingly, information managed by typical perinatal mortality classifications is often very restricted. As reviewed elsewhere,^[7] classifications broadly manage information in two partly overlapping groups: Some include categories best suited for epidemiology and health care planning purposes, including risk factors such as small for gestational age (SGA)^[8] and twin pregnancy,^[9] without (or with questionable) claims to represent COD. Others aspire to manage information on COD, often focusing on specific clinical groups or categories related to biomedical research questions.^[10,11,12] There is also diversity in the preferred source of information; encompassing to various degrees clinical obstetric diagnoses, pathology reports, full medical charts, or simply routinely provided ICD-codes. In testing contemporary classifications of stillbirths, Flenady et al found inconsistent approaches to the main categories of stillbirth, making datasets and classifications difficult to compare.^[7] These problems are especially noteworthy regarding the classification of placental causes of death.^[13] But despite apparently conflicting priorities, all categories are easily combined into one utilitarian system managing the most significant information irrespective of source or intended use.

In most clinical and research settings, in ICD, in death certificates and cause of death registries the COD is the main focus, based on the concept of underlying causal conditions. Associated conditions as, for example, SGA and twin pregnancy may be less valued. When relevant, these can often be deduced from the specified COD, but not vice versa. E.g. SGA engulfs just about every lethal chronic condition in fetal life, and when twinning is truly part of the causation, it will be captured by COD as entangled cords, twin-to-twin transfusion, etc.

The best understanding of COD is provided by the well educated health care micro-system surrounding the woman, which may include her clinical care providers, microbiologist, geneticist and perinatal pathologist. A multidisciplinary audit group reviewing deaths at her birthing institution remains the "Gold Standard" for classification of perinatal deaths, and the backbone for improvement of care through feedback.^[14] They collect all relevant information for classification and establish diagnoses, and have the narrative - the sequence and relative significance of events - to understanding why the death occurred. A classification should preserve and manage information on both individual conditions and their relative importance from the narrative.

Availability and appropriateness of care is sometimes an essential part of the narrative, and this information is needed to guide health care policies for the prevention of deaths. To preserve information about an intrapartum death, "unavailable obstetric care" may be more important than "malpresentation" in developing countries, but sub-optimal care is also frequently reported in perinatal deaths in developed countries,^[15] and this must be understood and such deaths prevented.

The Continuum of Perinatal Loss

The numerator in perinatal mortality classification is the number of individual fetuses entering the perinatal period alive, and dying before it ends. The perinatal period is defined (see Table 4 ) by the WHO as being ≥ 500 grams, and only secondarily ≥ 22 weeks,^[6] as gestational age is often unknown in developing countries. Yet, in practice, gestational age has been used interchangeably with birthweight in many settings, and most legal implications are linked to gestational age.^[16,17,18] Gestation at birth is commonly used, but should be corrected if time of intrauterine death is known. Valid arguments can be made for other limits of gestation, but for uniform reporting the limit at 500 grams/22 weeks is internationally established, and the WHO also recommend reporting data for international comparisons with the limits 1000 grams/28 weeks/35 cm. Nonetheless, communities who use lower limits should register and classify all their cases and causes of death accordingly, and many would favor also registering late neonatal deaths until the 28th postnatal day (rather than the 7th postnatal day) to capture more deaths with origins in perinatal events.

It should be noted that mean birthweight of stillbirths is significantly below 500 g at 22 completed weeks. Communities using the birthweight criterion will underestimate their stillbirth rate compared with regions using gestational age. In a population-based material with close to universal ultrasound-dating,^[19] 10.4% of stillbirths (> 22 weeks) would be unreported if the birthweight criterion was used.

In addition to variations in definitions, incomplete registrations, and differences in registration preferences and cultures, two classification issues hamper comparisons of stillbirth rates: "truncated" data due to terminations of pregnancy, and the "transfers" from stillbirths to neonatal deaths due to medical interventions (e.g. early delivery for hypertensive disorders). To enable interpretation of cause-specific perinatal death rates, information on both terminations and neonatal deaths must be managed together with stillbirths.

Neonatal deaths are often reported at any gestation as long as signs of life are seen. Yet, for consistency, the numerator should remain the same, and neonatal deaths only reported for the cases who have entered the perinatal period alive (500 g/22 weeks corrected post-natal age or weight/length at time of death) and thus qualifying as perinatal deaths.

No criteria can capture terminations with equal consistency. They will cause variations in perinatal mortality reports, some jurisdictions having mandatory registration of terminations among perinatal deaths.^[20] When using the same criteria to register both terminations and spontaneous deaths, higher termination rates yields lower anomaly mortality rates^[20] (many terminations prior to 22 weeks, not registered, would die perinatally if continued), while extending registrations to include lower gestational age criteria for terminations than for spontaneous deaths add the opposite effect (anomalies may cause death prior to perinatal life, and should not be included). With no perfect solution, the inevitable compromise should reflect the purpose of classification; capturing information on causal contributors to perinatal mortality.

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Abstract and Background
Methods
Results
Discussion
Conclusion
References

Table 1. Level I Categories of Codac
Categories of the primary causes of death (COD) and associated conditions (AC)
0	Infectious causes of death (abbrev: Infection)
	Deaths caused by infections affecting the mother, neonate or intrauterine structures and compartments directly are coded here by the causative agents as the primary COD. This includes lethal effects of infection by leading to congenital anomalies, by causing direct failure of the placenta or vital fetal/neonatal/maternal organs, or by initiating pre-viable preterm labor. The locus of the infection may be coded in subsequent positions.
1	Conditions, diseases and events specific to neonatal life (abbrev: Neonatal)
	Neonatal deaths caused by conditions or events specific to neonatal life are coded in this category as primary COD. Other COD and AC for neonatal deaths may be coded in any other relevant category.
2	Mechanics and events of parturition or its complications (abbrev: Intrapartum)
	Deaths occurring after onset of labor (intrapartum or neonatal) and where the most significant causal mechanisms were initiated by the onset, progress or complication of labor, are coded in this category as primary COD. Cases in which pre-existing conditions had reduced fetal survival potential to such an extent that mortality in normal and otherwise uncomplicated labor is significant (proportion > 0.05) if undelivered, should be coded with that condition as the primary COD with Intrapartum in a subsequent position.
3	Congenital anomalies, chromosomal anomalies and structural malformations (abbrev: Congenital anomaly)
	Deaths caused by congenital and chromosomal anomalies and structural fetal malformations, including effects of amniotic banding, are coded here as primary COD. Malformations of the placenta and cord are coded in those categories, with the exception of amniotic banding which are all coded here, irrespective of structures affected. Disruptions/deformations due to maternal uterine malformations are coded in Maternal. Congenital neoplasia is coded in Fetal.
4	Fetal conditions, diseases and events (abbrev: Fetal)
	Deaths caused by any fetal condition, disease or event (except Congenital anomaly) are coded here as primary COD. This includes those caused by placental transfer of toxins, or maternal antibodies against fetal tissues (as in alloimmunization) that does not constitute a maternal disease. The effects of maternal antibodies against her own tissues (as in anti-cardiolipin syndrome causing placental thrombosis or SS-A/SS-B antibodies causing fetal arrhythmias), should however be coded in Maternal.
5	Cord conditions, diseases and events (abbrev: Cord)
	Deaths caused by any condition, disease or event affecting the umbilical cord and its insertion are coded here as primary COD. If the same process has been shown to be present and equally significant in the fetal compartment, the primary COD should be coded there, if applicable.
6	Conditions, diseases and events of the placenta and membranes (abbrev: Placenta)
	Deaths caused by any condition, disease or event affecting the placenta and membranes are coded here as main COD. If the same process has been shown to be present and equally significant in the fetal or cord compartment, the primary COD should be coded there, if applicable.
7	Maternal conditions, diseases and events (abbrev: Maternal)
	Deaths caused by any maternal condition, disease or event, of a sufficient degree to significantly increase the risk of perinatal death are coded here as primary COD. If the same process has been shown to be present and equally significant in the fetal, cord or placental compartment, the primary COD should be coded there, if applicable.
	This category includes conditions that was unrelated to of pregnancy (as in maternal cancer), was incompatible with a viable pregnancy (as in Ehler-Danlos syndrome), was exacerbated by the normal physiology of pregnancy (as in anti-phospholipid syndrome), or was caused by uncertain mechanisms of pregnancy, and yet poses serious threats to maternal and fetal health (as in acute fatty liver of pregnancy). In exceptional cases, the category may include maternal pathology provoked by non-lethal pathophysiology of pregnancy (as in acute onset pregnancy-induced hypertensive crisis with apparently minimal placental pathology). Symptoms (as hypertension) caused by intrauterine pathologies (as placental insufficiencies) should not be coded as a COD, but may be coded in subsequent positions.
8	Unknown, unexplained and unclassifiable causes of death (abbrev: Unknown)
	Neonatal, antepartum, and deaths with unknown timing, in which no definite or probable COD has been found are coded in this category as the primary COD. Otherwise unclassifiable cases are also coded here. This category only exists for causes of death, and is replaced by Associated perinatal for AC.
9	Terminations of pregnancy (abbrev: Termination).
	All deaths caused by termination of pregnancy are coded in this category as the primary COD. This is irrespective of the indication, timing of death, or whether termination was performed by health professionals or not. It includes augmentations of labor in cases of expected unavoidable death, and also cases in which death did not occur before the completion of delivery. This category only exists for causes of death, and is replaced by Associated maternal for AC.
Categories specific to associated conditions
8	Associated conditions and complications in the perinatal period (abbrev: Associated perinatal)
	AC and complications of pregnancy are coded here in the secondary or third position.
9	Associated maternal conditions and identified risk (abbrev: Associated maternal)
	AC and identified risk of the mother are coded here in the secondary or third position.

Table 2. Coding Rules in Codac
1.	To be a COD, the condition(s combined) should have significant lethality (≥ 0.05) in the clinical setting it was observed.
2.	If no COD was found, code antepartum stillbirths and neonatal deaths as 8xx and intrapartum deaths as 29x.
3.	If two (or more) conditions could be COD, select the most significant contributor to death.
4.	If two equally significant conditions could be COD, code the first to occur if this can cause the latter (related conditions)
5.	If two equally significant conditions could be COD, code the last to occur if this cannot cause the first (unrelated conditions)
6.	If two equally significant conditions of unknown timing could be COD, code the first among codes 0 to 7 (hierarchically).
7.	If COD was infectious, code as 0xx (000 if unknown agent) and report the locus as AC in 19x, 49x, 59x, 69x or 79x.
8.	If any act to advance death was performed (termination), code as 9xx, and conditions leading to termination as AC.
9.	To be an AC, the condition(s combined) should contribute significantly in explaining the circumstances of death.
10.	Do not code any condition(s) unrelated to the causes or circumstances of death.

Table 3. Agreement Among Coders
	Coder 6	Coder 5	Coder 7	Coder 3	Coder 2	Coder 4
Coder 1	0.82	0.71	0.73	0.70	0.70	0.53
Coder 6		0.71	0.68	0.63	0.74	0.57
Coder 5			0.67	0.61	0.69	0.51
Coder 7				0.61	0.56	0.52
Coder 3					0.63	0.54
Coder 2						0.59

Kappa values for the agreement in coding of the main cause of death category among coders. Coders are listed (left to right and top to bottom) by their falling adherence to the coding instructions of Codac. Mean adherence of coders 1 & 6 (top left) was 78% and of coders 2 & 4 (bottom right) was 30%.

Table 4. Definitions
Perinatal period The perinatal period commences as the birth weight passes 500 grams, or 22 completed weeks of gestation if weight is unknown, or 25 cm crown-heel length if weight and age is unknown, and it ends with the early neonatal period at 7 postnatal days.
Fetal death Fetal death is death prior to the complete expulsion or extraction from its mother of a fetus, irrespective of the duration of pregnancy; the death is indicated by the fact that after such separation the fetus does not breathe or show any other evidence of life, such as beating of the heart, pulsation of the umbilical cord, or definite movement of voluntary muscles.
Stillbirth A stillbirth is the birth after fetal death in the perinatal period.
Perinatal death A perinatal death is death during the perinatal period, and includes stillbirths and early neonatal deaths.
Cause of death A cause of death in stillbirth is an event, disease or condition of sufficient severity, magnitude and duration for death to be expected in a significant proportion of such cases in a continued pregnancy in the clinical situation it was observed. COD in the neonate is defined likewise by deleting the insert "... in a continued pregnancy ..."
Associated condition An associated condition of stillbirth is an event, disease or condition of sufficient severity, magnitude and duration to contribute in explaining the circumstances of death in a significant proportion of such cases in a continued pregnancy in the clinical situation it was observed. AC in the neonate is defined likewise by deleting the insert "... in a continued pregnancy ..."
Mechanism of death Mechanisms are biological pathways or chains of events that are initiated by an underlying cause, and consistently and irreversibly result in the same ultimate outcome when triggered by the same event.

Table 5. Simplified Codac
0) INFECTION	02 MALARIA
	04 SYPHILIS
	05 GROUP B STREPTOCOCCUS (GBS)
	06 COMMON BACTERIA OF MATERNAL FLORA (NON-GBS)
1) NEONATAL	11 EXTREME PREMATURITY
	13 CARDIO-RESPIRATORY
	19 INFECTION
2) INTRAPARTUM	23 MALPRESENTATION
	25 PROLONGED/OBSTRUCTED OR INCOMPLETE LABOR
	26 EXTREME PREMATURITY
	29 UNKNOWN (FETAL RESPIRATORY FAILURE/ASPHYXIA)
3) CONGENITAL ANOMALY	31 CENTRAL NERVOUS SYSTEM
	32 CARDIOVASCULAR AND LYMPHATIC VESSELS
	37 TRISOMIES
4) FETAL	43 ALLOIMMUNIZATION
4) FETAL	47 HYDROPS OF UNKNOWN ORIGIN
5) CORD	51 KNOTS
	52 LOOPS
	53 ABNORMAL INSERTION
6) PLACENTA	63 ABRUPTION
6) PLACENTA	64 INFARCTIONS AND THROMBI
7) MATERNAL	71 HYPERTENSIVE DISORDER
	73 DIABETES
	79 INFECTION
8) UNKNOWN	81 UNKNOWN	8) ASSOCIATED PERINATAL	81 SMALL FOR GESTATIONAL AGE
	85 UNEXPLAINED		83 MULTIPLES
	86 UNCLASSIFIABLE		89 SUBOPTIMAL CARE
9) TERMINATION	91 FOR CONG. ANOMALY	9) ASSOCIATED MATERNAL	91 OBSTETRIC HISTORY
	94 FOR FETAL DISEASE		92 SMOKING
	96 FOR MATERNAL CONDITION		95 POVERTY

If only the level I code is entered, the default level II subgroup is 0 = "Unspecified or other".

Table 6. Coding Examples
Case scenarios (selected cases used in agreement study) and coding comments by JFF:
Case 108. 34 yrs, G1, P0. Normal pregnancy till 41 w: Proteinuria (+3) and pregnancy induced hypertension (BP previously normal). Presented to birth clinic with contractions and rupture of membranes, non-reactive CTG, emergency CS, Apg 0-0-0. Baby girl. BW 2676 g, not IUGR. Placenta 600 g. Autopsy, PAD of placenta, screen for infections and Kleihauer neg. Unexplained death (acute intrapartal asphyxia, but unexplained why this happened).
"Coding rules 1 and 2 apply here. No condition fulfils criterions for a COD, but labor was a significant event and it should be coded 291 as COD. I would probably have added 714 for the preeclampsia as AC, but I would have liked to know more about the blood pressure."
Case 207. G7, P4. Unknown gestation (24-26?), no prenatal care. Smoke - < 10 cig/day. Alcohol in pregnancy - alcoholism. History no fetal movements preceding two weeks. Presenting with mild bleeding. Placenta small, extensive infarctions with fibrosis, thickened opaque membranes.
"The main problem here is rule 1. I'm not sure I can say what the COD was, but with the report saying both extensive infarctions and a small placenta, I would probably code 644. With this scarce report, I'm not sure her delay of 2 w without fetal movements is important, so rule 10 prevents me from coding 891 as an AC. I would add codes 921 and 931 for maternal smoking and alcoholism."
Case 210. 29 yrs, G7, P3, A3. Presented with ruptured membranes at 22 w and decreased fetal movements. SPROM x 3 days. Antibiotics antepartum and in labour. Breech. Fever. Oligohydramnios. Normal BP. History smoking during pregnancy < 10 per day. PAD of placenta report chorioamnionitis, marked deciduitis, Ascending infection. Dismature, numerous hemorrhages consistent with maternal hypertension.
"It doesn't say much about what happened around the time of death. But I read this as a death caused by an infection and rule 4 apply. I would code 000 as COD. As the site of infection I would code the placenta with acute chorioamnionitis in 691. In many cases these deaths will occur intrapartum due to extreme prematurity (code 262), but without evidence for it, I would code the lengthy PPROM as 862."
Case 402. 26 yrs, G2, P1. Previous baby 3200 g term and OK. Unbooked and presented with no fetal movements for 8-10 weeks. Induced and delivered a macerated stillbirth. Cell culture from chorionic villi, Trisomy 21.
"Little information on any actual cause of death. Yet, trisomy 21 does have an antepartum mortality > 5% even without any malformation, so according to rule 1 it should be coded 376."
Case 407. 32 yrs, G4, P2, TOP 1. Uneventful pregnancy. Presented with absence of fetal movements. Antepartum fetal death at 38 weeks. 3020 g. Autopsy, PAD of the placenta and all other tests performed according to guidelines with no findings. Unexplained.
"The case description is brief, but it states specifically that all tests were performed according to guidelines, and it should be coded as a true unexplained stillbirth - 861."

Authors and Disclosures

J Frederik Frøen, ^1,2 Halit Pinar, ³ Vicki Flenady, ^4,5 Safiah Bahrin, ⁶ Adrian Charles, ⁷ Lawrence Chauke, ⁸ Katie Day, ⁵ Charles W Duke, ⁹ Fabio Facchinetti, ¹⁰ Ruth C Fretts, ² Glenn Gardener, ⁴ Kristen Gilshenan, ⁵ Sanne J Gordijn, ¹¹ Adrienne Gordon, ¹² Grace Guyon, ¹³ Catherine Harrison, ¹⁴ Rachel Koshy, ⁶ Robert C Pattinson, ¹⁵ Karin Petersson, ¹⁶ Laurie Russell, ¹⁷ Eli Saastad, ^1,18 Gordon CS Smith, ¹⁹ Rozbeh Torabi ³

¹ Department of Genes and Environment, Division of Epidemiology, Norwegian Institute of Public Health, P.O. Box 4404 Nydalen, N-0403 Oslo, Norway
² Department of Obstetrics, Gynecology and Reproductive Biology, Harvard Medical School, Boston, MA, USA
³ Department of Pathology and Laboratory Medicine, Brown University Medical School, Providence, RI, USA
⁴ Department of Obstetrics and Gynaecology, University of Queensland, Mater Mothers' Hospital, Brisbane, Australia
⁵ Mater Mothers' Research Centre, Mater Health Services, Brisbane, Australia
⁶ Division of Family Health Development, Ministry of Health Malaysia, Putrajaya, Malaysia
⁷ Department of Paediatric and Perinatal Pathology, King Edward Memorial Hospital, Perth, Australia
⁸ Department of Gynaecology and Obstetrics, Kalafong Academic Hospital, Pretoria, South Africa
⁹ National Center on Birth Defects and Developmental Disabilities, Centers for Disease Control and Prevention, Atlanta, GA, USA
¹⁰ Unit of Psychobiology of Reproduction-UCADH, Mother-Infant Department, Università di Modena e Reggio Emilia, Modena, Italy
¹¹ Department of Obstetrics and Gynaecology, University Medical Centre Groningen, University of Groningen, Groningen, The Netherlands
¹² Department of Neonatal Medicine, Royal Prince Alfred Hospital, Sydney, Australia
¹³ Alberta Perinatal Health Program, Edmonton, Canada
¹⁴ Telethon Institute for Child Health Research, Centre for Child Health Research, The University of Western Australia, Subiaco, Australia
¹⁵ Department of Obstetrics and Gynaecology, University of Pretoria School of Medicine, Pretoria, South Africa
¹⁶ Department of Obstetrics, Karolinska University Hospital, Stockholm, Sweden
¹⁷ Division of Anatomical Pathology, Department of Laboratory Medicine & Pathology, University of Alberta Hospitals, University of Alberta, Edmonton, Canada
¹⁸ Department of Midwifery, Faculty of Nursing Education, Akershus University College, Lillestrøm, Norway
¹⁹ Department of Obstetrics & Gynaecology, School of Clinical Medicine, University of Cambridge, Cambridge, UK

Competing interests: The authors declare they have no competing interests.

Authors' contributions: JFF lead the development of the original Codac system in consultation with HP, oversaw the study and revision of the Codac system, and drafted the manuscript. VF oversaw the testing of the Codac system and analyzed the results with KG. SJG cross-referenced the revised Codac system to ICD-10 in consultation with JFF. CWD, FF, RCF, SJG and GCCS critically reviewed the revised version of Codac and the scientific content of the manuscript. All other investigators formed the classification teams and undertook review of stillbirth cases and data collection. All authors interpreted results, edited drafts of the manuscript and electronic Codac system, and read and approved the final manuscript.

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Causes of Death and Associated Conditions (Codac) - A Utilitarian Approach to the Classification of Perinatal Deaths

Abstract

Background

A Classification and Its Purpose

Selecting the Right Information

The Continuum of Perinatal Loss

Tables

Tables

Tables

Tables

Tables

Tables

References

Authors and Disclosures

Authors and Disclosures

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