Table 1 Table of included studies

12

Wood et al (2009)

Cohort

158,502

Alberta Perinatal Health Program, 1991-2004 Canada

Smokers: Yes

Fetal death after at least 24 completed weeks of gestation.

Adjusted OR 1.04 (0.74-1.47)

Maternal age, diabetes, hypertension, previous caesarean section.

Not validated

13

Smith et al (2007)

Cohort

84,769

Scotland morbidity records 1991-2001, UK

Smokers: Yes

Fetal death after at least 24 completed weeks of gestation.

OR for smoking was calculated 2.15 (95% CI 1.74-2.65)

Age, deprivation, height, BMI, Marital Status.

Not validated

14

Hogberg and Cnattingius (2007)

Cohort

526,691

Sweden – Swedish National study 1983-2001- Participants with two consecutive pregnancies.

Smokers: Yes

Fetal death after at least 28 completed weeks of gestation.

OR for smoking in both Pregnancies 1.35 (1.15-1.58). 1-9cig/day OR 1.16 (0.92-1.46) ≥10 cig/day 0R 1.55 (1.17-2.04). OR for smoking in the 1^st pregnancy only OR 1.02 (0.79-1.30), 1-9 cig/day OR 1.13 (0.9-1.39), ≥10 cig/day OR 1.14 (0.87-1.51). OR for smoking in 2^nd pregnancy only 0.84 (0.55-1.26), 1-9cig/day OR 1.10 (0.89-1.35), ≥ 10 cig/day OR 1.45 (1.16-1.81).

Maternal age, education, cohabiting with infant’s father, mother’s country of birth, year of second delivery, inter-pregnancy interval and stillbirth in first pregnancy.

1-9 cig/day, ≥10 cig/day.

Not validated

26

Salihu et al (2008)

Case control

1,444,378

USA – Missouri 1978-1997.

Smokers: Yes

In-utero fetal death at least 20 week into gestation.

a) Bidirectional case cross-over OR 1.20 (1.03-1.39) 1-9 cig/day OR 1.16 (0.88-1.53) 10-19 cig/day OR 1.10 (0.90-1.24) ≥ 20 cig/day OR 1.21 (1.01-1.50),

Maternal race and age.

1-9 cig/day,

10-19 cig/day,

b) Case Control OR 1.34 (1.26-1.43) 1-9 cig/day OR 0.94 (0.76-1.70) 10-19 cig/day OR 1.31(1.22-1.41) ≥20 cig/day OR 1.43 (1.31-1.54).

≥20 cig/day.

Not validated

34***

Ahlenius and Thomassen (1999)

Cohort

94,270 in 1984 and 124,201 in 1991.

Sweden - Using the Swedish medical birth register in 1984 and 1991

Smokers: Yes.

Death of a fetus before or during delivery with a gestational duration of at least 28 weeks.

Combined (1984 and 1991) OR 1.37 (1.17 to 1.61)

Maternal age and parity.

1-9 cig/day, ≥10 cig/day.

1-9 Cig/day OR 1.22

(1.00-1.48)

Not validated

≥10 Cig/day OR 1.62 (1.31-2.00)

1991 OR

1.47 (1.19 to 1.82)

>10 Cig/day OR 1.97 (1.51-2.59)

36***

Aliyu et al (2007)

Cohort

1,436, 725

USA Missouri – Using Missouri maternally linked cohort data 1978 – 1997

Smokers: Yes

In utero fetal death at < = 20 weeks gestation

OR(originally presented as HRs) 1.43 (1.36-1.51)

N/A*

1-9 cig/day, 10-19 cig/day, ≥ 20 cig/day.

Not validated

37

Gray et al (2009)

Cohort

532,016

UK- Scotland, National study 1994-2003.

Smokers: Yes.

24-44 weeks’ gestation

OR 1.75 (1.61-1.91)

N/A*

Not validated

38

McCowan et al (2007)

Cohort

69,173

New Zealand - National Women’s

Smokers: Yes

Birth of a baby with no signs of life delivered at ≥

OR 1.33 (0.99-1.79)

Infant sex, maternal ethnicity, parity, marital status, maternal age at delivery, history of previous miscarriage, history of previous abortion, previous low-birth weight infant, previous C-section.

Hospital, Auckland, New Zealand from 1993 to 2000

Not validated

20 weeks or with a birth weight of > 400 g if gestation was not known.

39

Miller et al (2010)

Cohort

359,747

Canada – Ontario state 2004-2006

Smokers: Yes

Death of fetus at 20 weeks of gestation

Overall OR 1.58 (1.38-1.81)

Age, parity, multiple gestation

Not validated

40

Moshin et al (2005)

Cohort

433,227

Australia – New South Wales 1998-2002

Smokers: Yes

Fetal death at ≥ 20 weeks gestation or of 400 g or more birth weight.

Overall adjusted OR 1.17 (1.05–1.31) Unadjusted OR 1.05 (0.94–1.17).

Maternal age, maternal country of birth, socioeconomic status, maternal diabetes mellitus, and first antenatal care visit.

Not validated

17***

Raymond et al (1994)

Cohort

638,242

Sweden National study 1983-1989

Smokers: Yes

Fetus death at 28 weeks of gestation or more.

OR 1.4 (1.2-1.4)

Age, parity, pregnancy complications, hypertensive diseases, diabetes, placental complications and intrauterine growth retardation (IUGR).

Not validated

42

Reddy et al (2006)

Cohort

174,809

USA – 12 clinic centres and 19 hospital sites. 2002-2008.

Smokers: Yes

Fetal death at 23 weeks gestation and beyond.

OR (originally presented as HRs) 1.57 (1.21-2.02)

N/A*

Not validated

43

Sutan et al (2010)

Cohort

541,811

UK- Scotland, National study (NHS Hospital)

Smokers: Yes

Late fetal death from 20 weeks gestation.

OR 1.64 (1.46-1.84)

Non stated

Not validated

44

Tuthill et al (1999)

Cohort

16,047

Wales – All Wales Perinatal Survey 1993-1995

Smokers: Yes

Mortality from 20 completed weeks of gestation

OR 1.72(1.38-2.13)

Social class, infection, placental abruption, sudden infant death syndrome.

Not validated

45

Wisborg et al (2001)

Cohort

25,102

Denmark – Aarhust University Hospital 1989-1996.

Smokers: Yes

Delivery of a dead fetus occurring at 28 weeks or more gestation.

OR 1.9 (1.3-2.9),

Sex of child, parity, maternal age, education, alcohol, caffeine intake.

1-9 cig/day, ≥10 cig/day.

1-9 cig/day OR 1.5 (0.9-2.4) ≥10 cig/day 1.8 (1.2-2.8)

Not validated

46

Winbo et al (2001)

Cohort

1,412,747

Sweden – National study 1983 - 1995

Smokers: Yes

Death of fetus after competing 28 weeks of gestation.

OR stillbirths ≥37 weeks compared with live births 1.08 (0.96-1.22)

Non stated

Not validated

27

Ferraz and Gray (1991)

Case control

11,483

Brazil – Natal city and state of Rio Grande do Norte 1984-1986

Smokers: Yes

Stillborn cases weighing 500 g or more

OR 1.4 (1.0-2.0)

Non stated

Not validated

29

Dodds et al (2006)

Case control

494

Canada – Nova Scotia and Eastern Ontario 1999-2001

Smokers: Yes

Not specified - Death before delivery of a fetus weighing 500 g or more

OR (originally presented in HRs) Smoking during 1^st trimester 2.13 (1.23-3.64)

N/A*

Not validated

30

Efkarpidis et al (2004)

Case control

599

UK – Nottingham City Hospital 1991-1997.

Smokers: Yes

Definition of stillbirth not stated- pregnancies considered from ≥ 24 weeks

OR 1.2 (0.64-1.6)

Non stated

Not validated

31

Froen et al (2002)

Case control

598

Norway – Oslo 1986-1995.

Smokers: Yes

Intrauterine death before onset of labour of a fetus > =22 weeks gestation or > = 500 g body mass

OR calculated Using Stats 1.81 (1.02-3.15) 1-9 cig/day OR 1.0 (0.43-2.12), ≥10 cig/day 0R 3.04 (1.13-8.19)

N/A*

1-9 cig/day, ≥10 cig/day.

Not validated

32

Goy et al (2008)

Case control

510

Canada – Nova Scotia and Eastern Ontario 1999-2001.

Smokers: Yes

Not specified - Death before delivery of a fetus weighing 500 g or more

OR 2.06 (1.22-3.47)

Province of origin, age, inactivity during pregnancy, stillbirth in previous pregnancy, used fertility treatment

Not validated

33

Little and Weiberg (1993)

Case control

4667

USA

Smokers: Yes

Fetal death at 28 weeks or more gestation

OR calculated using Stata 1.29 (1.09-1.53)

N/A*

1-19 cig/day,

OR 1-19 cig/day 1.3 (1.09-1.57), 20-29 cig/day OR 1.39 (1.06-1.82), ≥30 cig/day OR 0.67 (0.41-1.12).

20-29 cig/day,

≥ 30 cig/day.

Not validated

47

Mishra et al (2005)

Cross-sectional

16,802

India - Survey conducted 98-99

Smokers: Yes

Delivery of a dead baby at > 28 weeks of pregnancy

OR 1.23 (0.92-1.64)

Cooking smoke, anaemia, BMI, education, standard of living, house type.

Not validated

Unadjusted OR 1.60 (1.23-2.08).

48

Robson et al (2006)

Cross-sectional

21, 880

Australia – New South Wales 1998-2003.

Smokers: Yes

Not stated

OR 1.65 (1.15-2.38)

Age, parity, medical/obstetric complications

1-10 cig/day >10 cig/day.

20 weeks

1- 10 cig/day OR 1.16 (0.80-1.69) >10 cig/day OR 1.68 (1.17-2.41).

Not validated

16***

Cnattingius et al (1988)

Cross-sectional

262,582

Sweden National Study – Using Swedish medical birth registry covering more than 99% of all births in Sweden. 1983-1985

Smokers: Yes

Late fetal death – still birth occurring at 28 weeks of gestation or later

OR (originally presented as RR) 1.37 (1.20-1.57)

N/A*

1-9 cig/day,

1-9 cig/day 1.32 (1.12-1.55)

≥10 cig/day.

≥10 cig/day 1.45 (1.21-1.75)

Not validated

28***

Walles (1994)

Case control

202

Sweden – 5 centres (Boras, Helsingborg, Karlskrona, Kristianstastad and Lund) 1983-1989.

Smokers: Yes

Definition of stillbirth not stated, pregnancies considered

OR calculated using Stata. OR 1.18 (0.62-2.26)

N/A*

1-10 cig/day,

1-10 cig/day OR 1.33 (0.58-3.09) >10 cig/day 1. 04 (0.43-2.50)

≥10 cig/day.

≥ 28 weeks

Not validated

35***

Aliyu et al (2008)

Cohort

1,436,628

USA Missouri – Using Missouri maternally linked cohort data 1978 – 1997.

Smokers: Yes.

In utero fetal death at < = 20 weeks gestation.

OR (originally presented as HRs) 1.48 (1.40-1.56)

N/A**

< 35 years old, ≥ 35yers old. Not validated

< 35 years smokers1.43 (1.35-1.51)

≥35 years Smokers OR 2.4 (2.06-2.80)

49

Kleinman et al (1988)

Cohort

362,261

USA Missouri 1978-1983

Smokers: Yes

(Fetal mortality) Fetal death at 20 weeks or more.

OR Primiparas

N/A**

< 1 pack/day ≥1 pack/day.

<1 pack/day 1.36(1.16-1.59) ≥1 pack/day 1.62 (1.34-1.97)

Not validated

Multiparas

<1 pack/day 1.21 (1.06-1.38) ≥1pack/day 1.15(0.99-1.34)

50

Raatikainen et al (2006)

Cohort

25,591

Finland-Kuopio University Hospital 1989-2001.

Smokers: Yes.

Fetal death was defined as intrauterine death before

No estimates

N/A**

Not validated

22 weeks of pregnancy or 500 g fetal weight.

51

Aliyu et al (2010)

Cohort

633,849

US Missouri – Using Missouri maternally-linked cohort data files 1978 – 1997.

Smokers: Yes

In utero fetal death at > = 20 weeks gestation.

Results HRs,

N/A**

Not validated

<15 years 3.3 (1.4-7.8), 15-19 years 1.7 (1.5-1.9), 20-24 years 1.5 (1.4-1.6)

No sufficient data to calculate Odds ratios.

52

Bai et al (2000)

Cohort

7138

Australia- Liverpool hospital Sydney March 1996 to June 1998

Smokers: Yes

Not Clear (births occurring at less than 20 weeks gestation age exclusion criteria).

Results presented in Percentages. No odds ratios and no sufficient data to calculate OR.

N/A**

Not validated

53

Huang et al (2000)

Cohort

84,294

Canada – The Royal Victoria Hospital in Montreal 1961-1974 and 1978-1996.

Smokers: Yes

Fetal deaths occurring before labour without evidence of significant fetal, maternal or placental pathology weighing 500 g or more.

No estimates

N/A**

Not validated

18

Schramm (1997)

Cross-sectional

176,843

USA – Missouri 1978-1990

Smokers: Yes Not validated

Fetal death greater or equal to 20 weeks gestation.

Results in RR no sufficient data to calculate OR

N/A**

Smoking in 1^st and not in 2^nd pregnancy RR 1.11, Not smoking in 1^st but in 2^nd pregnancy RR 1.6.smoking in both pregnancies RR 1.19.

54

Salihu et al (2004)

Cross-sectional

7,792,990

USA – 1995-1997.

Smokers: Yes

Intrauterine fetal demise after 20 weeks of gestation.

Estimates in Hazard ratios not enough data to calculate OR.

N/A**

Not validated

≥ 40 years 2.71 (1.88-3.91), 30-39 years 1.58 (0.96-2.60), 20-29 years 1.41 (1.16-1.71)