Table 1 Study characteristics

Rasmussen

Norway, 1967-1998 [14]

Population-based retrospective cohort study

Unexplained antepartum fetal death defined as death before labour without known fetal, placental, or maternal pathology

All singleton births with at least 28 weeks of completed gestation

Gadow

Argentina, Bolivia, Brazil, Chile, Colombia, Costa Rica, Ecuador, Paraguay, Peru, Uruguay, and Venezuela, 1982-1986 [15]

Hospital-based retrospective cohort study

Death at ≥20 weeks of gestation and weight ≥500 g

All births, live or dead, weighing 500 g or more occurring in 102 participating hospitals distributed in 11 countries

Xu

Northern Finland, 1996

Population-based retrospective birth cohort study

Death at >28 weeks of gestation

All singleton births with at least 28 weeks of completed gestation and a birth weight of at least 1,000 g

Northern Finland, 1985-86

Qingdao, China, 1992 [16]

Smith

Scotland,1980-1996 [17]

Population-based retrospective cohort study

Death at ≥28 weeks of gestation and weight >500 g

All singleton first births weighing more than 500 g delivered between 28 and 43 weeks gestation in Scotland in 1980-1996

Petridou

Greece, 1989-1991 [18]

Population-based case-control study

Death at ≥28 weeks of gestation

All reported stillbirths within the National Statistical Service of Greece database between the study years with gestational age greater than or equal to 28 weeks

Kesmodel

Aarhus, Denmark, 1989-1996 [19]

Hospital-based retrospective cohort study

Death at ≥28 weeks of gestation

Danish women with singleton pregnancies who did not have an induced abortion and who provided information on alcohol intake while receiving routine antenatal care in the Department of Obstetrics and Gynaecology at Aarhus University Hospital, Aarhus, Denmark, between September 1989 and August 1996

Efkarpidis

Nottingham, UK, 1991-1997 [20]

Hospital-based case-control study

Fetal deaths diagnosed by ultrasound at ≥24 weeks of gestation

All singleton stillbirths excluding any <24 weeks gestation, at the Nottingham City Hospital between the study period formed the cases which were compared to a control group of pregnancies (n =499) delivered during the same time period, from same geographic population, selected using random allocation by computer

Nielsen

Tamil Nadu, India, 1995 [21]

Community-based prospective observational study

Not defined

All births within six months from the day of survey to Tamil speaking mothers residing in the survey area for more than two days and were not mentally retarded

Aliyu

Missouri, USA, 1, 1989-2005 [22]

Population-based retrospective cohort study

Death at ≥20 weeks gestation

Singleton births to mothers diagnosed with placental abruption within gestational age range of 20 to 42 weeks

Aliyu

Missouri, USA, 2, 1989-2005 [23]

Population-based retrospective cohort study

Death at ≥20 weeks gestation

Singleton births to mothers diagnosed with preeclampsia or eclampsia within the gestational age range of 20 to 42 weeks.

Engel

Newcastle, Australia, 1995-1999 [24]

Hospital-based retrospective cohort study

Not clearly defined. Based on the plot and results within the manuscript, stillbirths considered as death >20 weeks of gestation

All cases of singleton pregnancies for women aged 13 to 47 years at obstetric unit of John Hunter Hospital

Wen

Qingyuan, China, 1997-1998 [25]

Hospital-based retrospective study

Intrapartum fetal deaths at ≥20 weeks gestation or ≥500 g

All hospital-born (participating hospitals (n =18)) registered births between the study period

Sutan

Scotland, 1994-2003 [26]

Population-based retrospective cohort study

Unexplained antepartum stillbirth defined as deaths occurring before labour with no evident fetal, maternal, or placental abnormality sufficient to be considered as the cause of death

All singleton, pregnancies occurring at 20 completed weeks of gestation and more or occurring after the fetus reached a body mass of 200 g or more

Ingemarsson

Sweden, 1999-2000 [27]

Population-based retrospective study

Death at ≥28 weeks gestation

All pregnancies registered in the national medical birth registry with a gestational duration of at least 28 completed weeks or less if the infant was alive at birth

Mohsin

New South Wales, Australia, 1998-2002 [28]

Population-based retrospective cohort study

Death at ≥20 weeks and weight ≥400 g

All live births and stillbirths with at least 20 weeks gestation or with a birth weight of 400 g or more

Hadar

Petach Tikva, Israel, 1995-2007 [11]

Hospital-based retrospective cohort study

Death at >20 weeks of gestation or death when weight >500 g if gestational age unknown

All cases of stillbirths and overall deliveries during the study period

MacDorman

USA, 2003 [29]

Population-based retrospective study

Death at ≥20 weeks of gestation

All births in the year 2003 with 20 weeks of gestation or more

Yoonhee

Ghana, 2003-2008 [30]

Population-based cohort study

Death at ≥28 weeks of gestation

All pregnancies from 1^st July 2003 to 30^th September 2008 in seven contiguous rural districts

MacDorman

USA, 2004 [31]

Population-based retrospective study

Death at ≥20 weeks of gestation

All births in the year 2004 with 20 weeks of gestation or more

MacDorman

USA, 2005 [32]

Population-based retrospective study

Death at ≥20 weeks of gestation

All births in the year 2005 with 20 weeks of gestation or more

Mutihir

Nigeria, 2006-2007 [33]

Hospital-based prospective observational study

Death at ≥28 weeks of gestation

All births delivered at the maternity unit of Jos University teaching Hospital between Jan 2006 and April 2007

National Statistics (Office of)

England and Wales, 1990-2010

Population-based retrospective cohort study

Death at >24 weeks of gestation (or prior to 1993, death at >28 weeks of gestation)

Summary data on live and stillbirths by each year, published by The Office of National Statistics, UK