Table 2. Characteristics of included studies on the association between birth defects and childhood cancer.

Reference (location)	BD ascertainment	Pediatric cancer case ascertainment: cancer types, age group, diagnosis dates/years, case identification source	Comparison group ascertainment
Case-control studies
Stewart et al., 1958 [18] (England and Wales)	Maternal interview	Overall, 0–9 years, 1953–1955 (died of cancer), Registrar General	Controls were selected from birth registers matched to cases on age, sex, and locality.
Ager et al., 1965 [39] (Minnesota, U.S.)	Maternal interview/medical record verification. The authors note that “lesser conditions, such as nevi, were not recorded”.	Leukemia, 0–4 years, 1953–1957 (died of leukemia), Minnesota death certificates	Two control groups were included with a total of two controls per case. If available, sex-matched sibling controls were included with the birthdate closest to the index child and who had reached an age at the time of interview that was the same or older as the age of the index child when they died. Neighborhood controls were matched on sex and birth date within one year.
Swerdlow et al., 1982 [91] (United Kingdom)	The Oxford Survey of Childhood Cancer and antenatal clinical notes	Testicular tumors, 0–15 years, 1953–73 (died of testicular cancer), the Oxford Survey of Childhood Cancer	The comparison group was "all boys who died during the same period from malignant neoplasms other than of genital site or of teratoma histology".
Wilkins et al., 1984 [77] (Ohio, U.S.)	Ohio birth certificate files	WT, NR, 1/1/1950-10/31/1981, Columbus (Ohio) Children's Hospital Tumor Registry	Two controls per case were randomly selected from birth certificate files with one matched to the case on sex, race, and birth year and the other matched on these variables plus mother's county of residence.
Johnson et al., 1985 [66] (Texas, U.S.)	The Texas State Department of Health birth certificates. Both major and minor BDs were included.	NB, 0–14 years, 1964–1978 (died of NB), Texas death certificates	Two controls per case were randomly selected from birth certificates matched to cases on birth year.
Méhes et al., 1985 [19] (Switzerland)	Pediatric examination for minor BDs	Overall, leukemia, solid tumors, 1.6–22 years, NR, Swiss University Children's Hospitals of Basel and Zurich Oncologic Departments	Controls with infectious diseases were matched 1:1 to cases on sex, age, and ethnic origin. Siblings were also examined where available.
Bunin et al., 1987 [78] (Philadelphia, U.S.)	Parental interview	WT, 0–14 years, 1970–1983, three Philadelphia-area hospitals: Children's Hospital of Philadelphia, St. Christopher's Hospital for Children, and Wilmington Medical Center	Controls were selected by RDD matched to cases at a 1:1 ratio on telephone area code and exchange, birth year (within 3 years), and race.
Johnson et al., 1987 [62] (Texas, U.S.)	The Texas State Department of Health birth certificates	CNS, 0–14, deaths from 1964–1980, Texas Department of Health death certificates	Two controls per case were randomly selected from Texas live births frequency matched to cases on race, sex, and birth year.
Neglia et al., 1988 [67] (Minnesota, U.S.)	The Minnesota State Department of Health birth certificates. The authors note that BDs were coded by HICDA-9.	NB, 0–8.9 years, cases born since 1969, hospital review of NB cases seen in Minnesota and bordering states	Four controls per case were selected from live births in Minnesota matched to cases on birth year.
Shu et al., 1988 [48] (Shanghai, China)	Interview of parents, grandmothers, and other relatives	Leukemia, 0–14 years, 7/1/1974-6/30/1986, Shanghai Cancer Institute Tumor Registry	Controls were selected from the Shanghai general population at random, matched to cases 2:1 on sex and birth calendar year.
Baptiste et al., 1989 [55] (New York State, U.S. (except New York City, Westchester, Rockland, Nassau, and Suffolk counties)	Maternal interview	CNS, 0–14 years, 1/1/1968-12/31/1977, New York State Cancer Registry	Controls were randomly selected from the New York State birth certificate files matched to cases at a 2:1 ratio on birth year, sex, and race.
Birch et al., 1990 [56] (United Kingdom)	Parental interview/medical record verification (ICD-9 coded 740–759)	CNS, 0–14 years, 1980–1983 from regional pediatric oncology centers, West Midlands Regional Cancer Registry, Manchester Children's Tumor Registry, Yorkshire Regional Cancer Registry	Two sets of controls were ascertained from general practitioner lists and hospitals matched to cases on sex and age. The second set excluded children with "a genetic or other constitutional disease or malformation known to be associated with increased risk of cancer" and any other major malformation or chronic disease.
Magnani et al., 1990 [47] (Italy)	Interview of parents/closest relatives	ALL, AML, NHL, NR, 1974–1984, Pediatric Hospital in Turin	Controls were a random sample of children hospitalized at the same hospital as cases.
Kajtár et al., 1990 [79] (Hungary)	Examinations of spine for vertebral anomalies on i.v. pyelograms in cases and X-rays in controls	WT, NR, NR, Department of Pediatrics, University Medical School, Hungary	Controls were children with X-ray for acute abdomen or trauma.
Zack et al., 1991 [40] (Sweden)	The Swedish Medical Birth Registry (ICD-8 codes 740–759)	All leukemias, lymphatic leukemias, myeloid leukemias, other or unspecified leukemias, 0–11 years, 1973–1984, the Swedish National Cancer Registry and Swedish Registry of Causes of Death	Five controls per case were selected from the Swedish Medical Birth Registry matched to cases on sex, birth year and month.
Schumacher et al., 1992 [23] (Germany)	Chest X-ray examination for rib anomalies	Overall, yolk sac carcinoma, OS, HD, histiocytosis X, NHL, ES, WT, STS, ALL, brain tumor, NB, 9 months-21years, NR, University Children's Hospital, Langenbecksrasse	Chest roentgenograms from patients without cancer with a similar age distribution as cases (15 months-14 years) were reviewed for comparison.
Mann et al., 1993 [16] (United Kingdom)	Parental interview/medical record verification (ICD-9 coded)	Overall, ALL, other leukemia, HL, other lymphomas, CNS, STS, bone tumors, WT, NB, RB, HB, GCT, epithelial tumors, Other neoplasms, 0–14 years, 1980–1983, regional pediatric oncology centers, West Midlands Regional Cancer Registry, Manchester Children's Tumor Registry, Yorkshire Regional Cancer Registry	Two sets of controls were selected from general practitioner lists and hospitals matched to cases on sex and age. The second set excluded children with "a genetic or other constitutional disease or malformation known to be associated with increased risk of cancer" and any other major malformation or chronic disease.
Savitz et al., 1994 [15] (U.S.)	Maternal interview or alternate respondent. BDs were recorded verbatim and blindly classified as major, minor, or not a defect.	Overall, ALL, brain, lymphoma, STS, 0–14 years, 1/1/1976-12/31/1983, primary data sources were the Colorado Central Cancer Registry and the Colorado Department of Health [106]	Controls were selected through RDD and frequency matching on location, sex, and age within 3 years.
Cordier et al., 1994 [61] (Ile de France, France)	Maternal interview. The authors noted excluding "minor anomalies such as nevi or birthmarks".	Brain, 0–15 years, 7/1/1985-6/30/1987, medical record abstractions from the neurosurgery, neurology, pediatric, pediatric oncology, or radiology departments at 13 hospitals	Controls were selected from the general population through sampling households on a representative list provided by the census bureau and telephone books at random matched to cases on birth year.
Gold et al., 1994 [64] (U.S.)	Parental interview	Brain, 0–17 years, 1/1/1977-12/31/1981 from eight Surveillance, Epidemiology, and End Results tumor registries	Three controls per case were identified through a variety of methods including RDD, lists of non-institutionalized individuals maintained by the Hawaii Department of Health and through a random sample of households (Pierce County, Washington). Controls were individually matched to cases on age, sex, and mother's racial/ethnic classification.
McCredie et al., 1994 [65] (Australia)	Maternal interview	Brain, 0–14 years, 1985–1989, New South Wales Central Cancer Registry	Two controls per case matched on sex and age were ascertained from eligible women on the Electoral Roll.
Yang et al., 1995 [86] (U.S.)	Parental interview. BDs were classified as major and minor.	RMS, 0–20 years, 4/1982-7/1988, Intergroup RMS study of the Children's Cancer Group and the Pediatric Oncology Group	Controls were ascertained by RDD matched to cases on telephone area code and exchange, sex, age, and race.
Shu et al., 1995 [89] (U.S., Canada, Australia)	Self-administered questionnaire	Malignant GCT, 0–14 years, 1982–1989, Children's Cancer Group	Controls were ascertained by RDD as part of the CCG-E04 pool.
Cnattingius et al., 1995 [49] (Sweden)	Swedish Medical Birth Register (ICD-8 to 1986 and ICD-9 after). Registration was completed upon mother and child leaving the hospital.	Lymphatic leukemia, 0–14 years who were born between 1973 and 1989, diagnoses through 1989, National Cancer Register	Five controls per case were selected from the source population who were alive at the case diagnosis and who were matched on sex, birth year and month.
Cnattingius et al., 1995 [41] (Sweden)	Swedish Medical Birth Register (ICD-8 to 1986 and ICD-9 after). Registration completed when mother and child leave the hospital.	Myeloid leukemia, 0–14 years who were born between 1973 and 1989, diagnoses through 1989, National Cancer Register	Same as Cnattingius et al., 1995 [49]
Adami et al., 1996 [54] (Sweden)	Swedish Medical Birth Register (ICD-8 to 1986 and ICD-9 after).	NHL, 0–14 years who were born between 1973 and 1989, diagnoses through 1989, the National Cancer Register	Same as Cnattingius et al., 1995 [49]
Gelberg et al., 1997 [12] (New York State, U.S., excluding New York City)	Telephone interview with the subject and/or parents, birth certificates and school and medical records	OS, 0–24 years, 1978–1988, the New York State Cancer Registry	Controls were ascertained from New York live birth records and matched to cases at a 1:1 ratio on birth year and sex.
Altmann et al., 1998 [17] (Victoria Australia)	The Victorian Perinatal Data Collection Unit Congenital Malformations/BDs Register (BDs coded according to the British Pediatric Association’s modification of the ICD-9). The authors noted that "the register collects information on both structural defects and chromosomal anomalies at birth…The register excludes certain trivial malformations, such as birth marks, skin tags and hydroceles." BDs were ascertained up to the age of 15 years.	Overall, leukemia (ALL, AML), CNS (astrocytoma), SNS (NB), lymphoma, STS (RMS), renal (WT), RB, germ cell/gonadal, bone, and hepatic, 0–14 years, 1/1/1984 to 12/31/1993, the Victorian Cancer Registrar	Four live born controls per who survived the neonatal period were selected from Victorian births at random and matched to cases on date of birth within 6 months.
Méhes et al., 1998 [52] (Germany)	Physical exam for mild errors of morphogenesis	Leukemia, 7 months-14 years, NR, the Department of Pediatrics, University Medical School of Pécs and the University Children's Hospital, Tübingen, Germany	There were two control comparison groups: 1) children with acute infectious diseases and 2) siblings.
Mertens et al., 1998 [43] (U.S., Canada, Western Australia)	Maternal interview (ICD-9 coded 740–759). Some minor BDs were included.	ALL, AML, cases from three different leukemia studies diagnosed at 0–18 months (CCG-E09), 0–17 years (CCG-E14), 0–14 years, 1983–1994 (CCG-E15), the Children's Cancer Group	Controls were selected from regional populations by a modified RDD method and matched on telephone exchange, age, and race (for E14 and E15).
Buck et al., 2001 [68] (New York State, U.S., excluding New York City)	Parental telephone interview/supplemented with data from birth certificates	NB, 0–5 years, 1976–1987, the New York State Cancer Registry	Controls were randomly selected from live birth registries and frequency matched to cases on birth year.
Infante-Rivard et al., 2001 [42] (Québec, Canada)	Parental interview for major BDs (ICD-9 coded 751–754)	ALL, 0–9 years, 1980–1993, Government-sanctioned tertiary care centers	Controls were selected from family allowance files and were individually matched to cases on age within 3 months, sex, and region of residence at diagnosis.
Roganovic et al., 2002 [50] (Rijeka, Croatia)	NR (minor BDs ascertained)	Hematologic, 5 months-16 years, 1983–1997, the Division of Hematology, Department of Pediatrics, University of Rijeka	Controls were healthy children that were the same age and gender as cases.
Méhes et al., 2003 [80] (Pécs, Hungary)	Abdominal roentgenograms and anteroposterior radiographs for cases; radiography for trauma or acute abdomen in controls; physical exam for both cases and controls. Spinal dysraphism ascertained.	WT, 2 months to 9 years for cases, NR, Department of Pediatrics, University Medical School of Pécs, Pécs, Hungary	Controls were children with radiography for trauma or acute abdomen ranging in age from 1–10 years.
Menegaux et al., 2005 [71] (U.S. and Canada)	Maternal interview (ICD-9 coded 740–759, both major and minor BDs were ascertained).	NB, 0–18 years, 1992–1994, the Children's Oncology Group	One control per case was selected by RDD individually matched to cases on date of birth within 6 months for cases aged <3 years and 1 year for cases aged >3 years.
Merks et al., 2005 [26] (The Netherlands)	Review of chest radiographs for rib anomalies	Overall, NB, GCT, RMS, WT, OS, ES, MB, AST, HD, AML, ALL, NHL, Other malignancies, 0–18 years, 1/1/1998-12/31/2002, Late Effects of Childhood Cancer Clinic and the Emma Children's Hospital, Academic Medical Center for newly diagnosed patients	Controls aged 0–18 years were selected from patient chest radiographs ordered by general practitioners and pediatricians in the outpatient ward and emergency room physicians.
Podvin et al., 2006 [44] (Washington State, U.S.)	Birth records	Leukemia, 0–19 years, 1981–2003, Washington State Cancer Registry and the Cancer Surveillance System of Western Washington	Ten controls without leukemia per case were randomly selected from the birth certificate records and were frequency matched to cases on birth year.
Urayama et al., 2006 [73] (California, U.S.)	Birth certificates	NB, 0–4 years, 1988–1997, California's statewide cancer registry	Two controls per case were randomly selected from birth certificates matched to cases on birth date and gender. Controls were replaced if they died younger than their matched case's diagnosis age.
Chow et al., 2007 [70] (Washington, U.S.)	Birth certificates (ICD-9 codes 740–759, major and minor BDs ascertained). For individuals who were born ≥1987 additional ICD-9 codes for discharges were obtained through linkage of birth certificates to the Comprehensive Hospital Abstract Reporting System.	NB, <20 years, 1993–2004, Washington State Cancer Registry & Cancer Surveillance System (CSS) of Western Washington	Ten controls without NB per case were randomly ascertained and were frequency matched on year of delivery.
Munzer et al., 2007 [69] (France)	Maternal telephone interview (ICD-10 coded Q00-Q99). BDs were classified as minor and major according to the European Surveillance of Congenital Anomalies.	NB, 0–14 years, 1/1/2003-12/31/2004, the National Registry of Hematological Cancer and the National Registry of Childhood Solid Tumors	Controls were randomly selected using phone numbers representative of the French population frequency matched to cases on age and gender.
Loder et al., 2007 [25] (Indiana, U.S.)	Chest radiographs were reviewed for rib number.	Overall, solid, lymphoproliferative, and neural, 1–12 years, malignancies cared for from 2001–2005, Riley’s Children’s Hospital Pediatric Tumor Registry	A similar sized control group identified from the Radiology Department logs was selected from children admitted at the same hospital for polytrauma.
Mallol-Mesnard et al., 2008 [58] (France)	Maternal interview. BDs were classified as minor and major according to the European Surveillance of Congenital Anomalies.	CNS, 0–14 years, 1/1/2003-12/31/2004, National Registry of Childhood Haematological Cancers and the National Registry of Childhood Solid Tumors	Controls were selected from the French population by sampling from 60,000 representative addresses taken from the French national telephone directory plus unlisted phone numbers generated randomly. Age and gender quotas were applied.
Merks et al., 2008 [21] (Amsterdam, Netherlands)	Clinical examination by a physician for major and minor anomalies. BD classification was based on Merks JH et al., 2003 [107].	Overall, 0–18 years, 1/2000-3/2003, Clinic for Late Effects of Childhood Cancer Clinic in the Emma Children's Hospital, Academic Medical Center	Controls were recruited from the city of Haarlem and the surrounding semirural and rural area.
Johnson et al., 2009 [88] (U.S. and Canada)	Maternal interview	GCT, 0–14 years, 1/1/1993-12/31/2001, the Children's Oncology Group	The control group was recruited through RDD and frequency was matched to cases on sex and birth year within 1 year at ratios of approximately 1:2 for males and 1:1 for females.
Johnson et al., 2010 [46] (U.S. and Canada)	Maternal interview. Both major and minor BDs were ascertained.	All infant leukemia, ALL, AML, 0–1 year, 1/1/96-10/13/02 (Phase I) 1/1/03-12/31/06 (Phase II), the Children's Oncology Group	Phase one controls (5/1999-10/2002) were sampled from the population through RDD. Phase two controls (10/2003-3/2008) were selected from state birth registries. Controls were frequency matched to cases on birth year and region of residence based on the phase one case distribution.
Durmaz et al., 2011 [20] (Turkey)	Two medical geneticists qualified in pediatric genetic dysmorphology examined patients for age-independent minor BDs by using the London Dysmorphology database.	Overall, hematopoetic, CNS, WT/GCT, RMS, OS, NR, NR, Cases were diagnosed at Ege University Faculty of Medicine, Izmir, Turkey	The control group was randomly recruited from the Pediatric Outpatient Service at the Ege University Medical Faculty.
Partap et al., 2011 [57] (California, U.S.)	California Office of Vital Records' birth certificate database	CNS, LGG, HGG, MB, PNET, GCT, EPD, 0–14 years, 1988–2006, California Cancer Registry	Four controls that matched to each case on birth date and sex were selected from the California birth certificate database.
Citak et al., 2011 [22] (Turkey)	Two pediatric hematologists/oncologists examined patients for minor BDs using the London Dysmorphology database	ALL, AML, chronic myelocytic leukemia, chronic myelomonocytic leukemia, MDS, 1.5–18 years, NR, cases diagnosed at a single institution	The control group consisted of healthy children of the same age, gender, and ethnicity.
Zierhut et al., 2011 [24] (Minnesota, U.S.)	Radiologists' X-Ray examination for rib anomalies	Overall, all acute leukemia, ALL, AML, lymphoma, CNS, NB, renal, bone tumors, sarcomas, 0–19 years, 2003–2009, the University of Minnesota Medical Center-Fairview	Controls were randomly selected pediatric patients who received a chest X-ray at Fairview Ridges Hospital in Burnsville, MN.
Rudant et al., 2013 [45] (France)	Maternal interview with structured questionnaires. BDs were classified as major and minor according to the European Surveillance of Congenital Anomalies.	All acute leukemia, ALL, AML, 0–14 years, 2003–2004, the National Registry of Childhood Hematopoietic Malignancies	Controls were recruited at random from the telephone directory using gender and age quotas in eight strata reflecting the expected distribution of all the cases.
Citak et al., 2013 [22] (Turkey)	Two pediatric hematologists/oncologists examined patients for minor BDs using the London Dysmorphology Database.	Overall, lymphoma, solid tumors, 0.1–18 years, NR, "2 different institutions"	Controls were selected from individuals seen at the healthy child clinic of Mersin University Hospital and Mersin Obstetric, Gynecology and Children Hospital, Department of Pediatric Hematology and Oncology who were within the same age range, sex, and ethnicity as cases.
Parodi et al., 2014 [72] (Italy)	Parental interview, structured questionnaire (ICD-9 coded 740–759)	NB, 0–10 years, 1998–2001, Pediatric Oncology Centers of the Italian Association of Pediatric Hematology and Oncology (AIEOP)	Controls were randomly selected from the National Health Service database matched on gender, date of birth and area of residence.
Venkatramani et al., 2014 [84] (U.S.)	Maternal interview/ the Utah Population Database (UPDB, ICD-9 codes 740–759)	HB, 0–5 years, 2000–2008, the Children's Oncology Group (COG) for the discovery cohort, the UPDB linked to the State Cancer Registry from 1978–2010 for the validation cohort	The discovery control group was identified from the birth registries from 32 states and matched to cases on birth weight, gender, birth year, and region. The validation control group was selected randomly from the Utah population and matched 10:1 to cases on gender and birth year.
Greenop et al., 2014 [60] (Australia)	Mailed exposure questionnaire	Brain tumors, NR (childhood), 2005–2010, 10 Australian oncology centers	Controls were recruited through random digit dialing and matched to childhood CBT cases on age, sex, and state of residence at a 3:1 ratio [108].
Santos et al., 2016 [109] (Brazil)	Exam for café-au-lait spots by two trained dysmorphologists	Solid tumors (clear cell renal cell carcinoma, CNS, EWS, fibrosarcoma, GCT, HB, OS, RB, RMS, synovial sarcoma, STS, WT), 0–18, NR, NR	Cases were from Rio De Janeiro and Sao Paulo. The control group was comprised of school children from Rio de Janeiro without a diagnosis of cancer or a predisposing syndrome.
Rios et al., 2016 [74] (France)	Maternal telephone interview (ICD-10 coded). Minor BDs or unspecified BDs were excluded according to the European Surveillance of Congenital Anomalies.	NB, <6 years, 2003–2004 (ESCALE) and 2010–2011 (ESTELLE), French National Registry of Childhood Cancer	The analysis was based on pooled data from two French case-control studies (ESTELLE and ESCALE). Controls were frequency matched to cases on sex and age so that there would be at least one control per case.
Hall et al.c, 2017 [90] (California, U.S.)	California birth certificates	GCT, yolk sac tumors, teratomas, ≤5 years, 1988–2013, California Cancer Registry	Controls were randomly selected from California birth records frequency matched to cases on birth year.
Bailey et al., 2017 [59] (France)	Maternal telephone interview	Brain tumors, 0–14 years, 2003–2004 (ESCALE) and 2010–2011 (ESTELLE), French National Registry of Childhood Cancer	Same as Rios et al., 2016 [74].
Cohort studies
Windham et al., 1985 [27] (Norway)	Medical Birth Registry (ICD-8 codes 740–759)	Overall, leukemia, nervous system tumors, renal cancer, eye cancer, NB, 0–13 years, 1967–1980, the Norwegian Cancer Registry	Individuals without BDs from the Norwegian Medical Birth Registry comprised the unexposed group.
Mili et al., 1993 [28] (Georgia, U.S.)	The Metropolitan Atlanta Congenital Defects Program (major BDs, six-digit code for reportable BDs, a modification of the British Pediatric Association Code, which uses a modification of ICD-9 codes). BDs were captured in the first year of life.	Overall, leukemia, brain tumors, NB, WT, RB, 0–14, 1/1/1975-12/31/1988, the Georgia Center for Cancer Statistics at Emory University	The expected number of cancer cases was calculated based on Atlanta Surveillance Epidemiology and End Results rates.
Mili et al., 1993 [29] (Iowa, U.S.)	The Iowa Birth Defects Registry (only major BDs, six-digit code for reportable BDs, a modification of the British Pediatric Association Code, which uses a modification of ICD-9 codes). BDs were captured in the first year of life.	Overall, leukemia, brain tumors, NB, sarcoma, 0–7 years, 1/1/1983-12/31/1989, the State Health Registry of Iowa's Cancer Registry (a SEER registry)	The expected number of cancer cases was calculated based on Iowa Surveillance Epidemiology and End Results rates.
Agha et al., 2005 [33] (Ontario, Canada)	Canadian Congenital Anomalies Surveillance System (ICD-9 codes 740.0–759.9). BDs were captured in the first year of life.	Overall, leukemia, lymphoma, CNS, sympathetic nervous system, RB, renal tumors, bone tumors, STS, GCT, trophoblastic and other gonadal carcinoma, and malignant epithelial, 0–19 years, 1979–1996, the Ontario Cancer Registry	Children without BDs were selected from the Birth Certificate File of Ontario. For every child with a BD, one child without BDs was selected matched on birth year, maternal age, birth order, mother's marital status, and parent's place of birth (Ontario vs. other).
Johnson et al., 2007 [37] (U.S.)	Both maternal interview using standardized tools and medical examinations of the children for birthmarks	Overall, 0–8 years, 1959–1966, the Collaborative Perinatal Project (CPP) subject population	Children without birthmarks in the CPP cohort were used as the comparison group.
Bjørge et al., 2008 [75] (Norway)	The Medical Birth Registry of Norway	NB, 0–14 years, 1967–2004, the Cancer Registry of Norway	The comparison group included all live born children in Norway during 1967–2004 without reported congenital malformations.
Rankin et al., 2008 [30] (Northern Region, United Kingdom)	Northern Congenital Abnormality Survey (ICD-10 coded BDs). The authors note including only "major congenital anomaly subtypes" BDs were captured in the first year of life.	Overall, ALL, AML, other leukemia, HL and NHL, brain, NB, WT, RB, RMS, and others, NR, 1985–2001, the Northern Region Young Persons Malignant Disease Registry	Children without BDs born in the Northern Region were used as the comparison group.
Carozza et al., 2012 [31] (Texas, U.S.)	Texas Birth Defects Registry (1979 British Pediatric Association Classification of Diseases and the 1979 ICD-9-CM, as modified by the U.S. CDC and the Texas Department of State Health Services). Major structural and chromosomal BDs were included. More minor defects were included if the individual also had a major BD. BDs were captured in the first year of life.	Overall, leukemia, lymphoma, CNS, NB, RB, renal tumors, hepatic tumors, malignant bone tumors, STS, GCT, other epithelial, 0–14 years, 1996–2005, the Texas Cancer Registry	All children live born in Texas and not registered in the Texas Birth Defects Registry who were identified through birth certificates were included as the controls.
Fisher et al., 2012 [36] (California, U.S.)	The California Birth Defects Monitoring Program and birth certificates (major BDs were classified based on the British Pediatric Association Classification of Diseases codes, as modified by the CDC). BDs were captured in the first year of life.	Overall, leukemia, lymphoma, CNS, NB, WT, Non-CNS germ cell, RMS, 0–14 years, 1988–2006, the California Cancer Registry	Children without major BDs born from 1988–2004 were used as the comparison group.
Botto et al., 2013 [32] (Utah, Arizona, Iowa, U.S.)	State Birth Defect Surveillance Program (selected major BDs as defined by the National Birth Defect Prevention Network); BD’s were captured up to 15 years of age.	Overall, leukemia, MDS/MPD, lymphoma, brain tumor, NB spectrum, RB, kidney tumor, liver tumor, sarcoma, germ cell, trophoblastic and gonadal tumor, 0–14 years, 1968–2005 for AZ, 1983–2005 for IA, 1994–2008 for Utah, Arizona and Utah state cancer registries	The comparison group included individuals without BDs selected randomly from state birth certificates who were frequency matched 3:1 to the cases by birth year.
Sun et al., 2014 [38] (Denmark)	Danish National Hospital Register (Danish version of ICD-8 codes from 1977–1993: 740–743, 746–747, 759, ICD-10 codes from 1994 onwards Q00-07, Q20-28, Q90-99)	Overall, CNS, mesothelial and soft tissue, skin, lymphatic and haematopoietic, other systems, 0–19 years, 1/1/1977-12/31/2007, Danish Cancer Registry	The comparison group consisted of all children without BDs live born in Denmark between 1977–2007 after excluding missing data, adopted children, twins, and chromosomal anomalies.
Dawson et al., 2015 [34] (Western Australia)	Western Australian Register of Development Anomalies (British Pediatric Association Classification of Diseases, a five-digit extension of ICD-9). BDs were captured in the first year of life.	Overall, leukemia, lymphoma, CNS, NB, RB, renal tumors, hepatic, bone, STS, gonadal and germ cell, other epithelia/melanoma, >90 days-14 years, 1982–2007, Western Australia Cancer Registry	The comparison group included all live born children with > 90 days of follow-up born in Western Australia from 1982–2007 BDs.
Janitz et al., 2016 [35] (Oklahoma, U.S.)	Oklahoma Birth Defects Registry (as defined by the CDC British Pediatric Association codes for congenital anomaly categories and classified according to the National Birth Defects Prevention Network (2004)). BDs were reported up to age 6 years but signs/symptoms must have been present by age 2 years.	Overall, leukemia, lymphoma, CNS, hepatic tumors, STS, GCT, 0–12 years, 1/1/1997-3/31/2009, Oklahoma Central Cancer Registry	The comparison group comprised all singleton births in Oklahoma from 1/1/1997 to 3/31/2009 who were not linked to the Oklahoma Birth Defects Registry.
Case-cohort studies
Johnson et al., 2008 [76] (Minnesota, U.S.)	Minnesota Birth Registry records	NB, 28 days-14 years, 1988–2004, Minnesota Cancer Surveillance System	The sub-cohort was comprised of four individuals per childhood cancer case randomly matched to cases on birth year who were born from 1976–2004.
Puumala et al., 2008 [82] (Minnesota, U.S.)	Minnesota Birth Registry records	WT, 28 days-14 years, 1988–2004, Minnesota Cancer Surveillance System	Same as Johnson et al., 2008 [76]
Spector et al., 2008 [85] (Minnesota, U.S.)	Minnesota Birth Registry records	HB, 28 days-14 years, 1988–2004, Minnesota Cancer Surveillance System	Same as Johnson et al., 2008 [76]
Nested case-control studies
Wanderas et al., 1998 [92] (Norway)	Medical Birth Registry (ICD-8 codes and classifications by the Medical Birth Registry and Statistics Norway). The authors indicate BDs of "all types" were included (Table 2). Recorded “presentation anomalies” (present at birth).	Testicular GCTs, 0–28 years, 1967 to June 1996, Norwegian Cancer Registry	Approximately 100 controls per case were obtained from the Norwegian Birth Registry for the birth period of 1967–1995.
Lindblad et al., 1992 [81] (Sweden)	Swedish Medical Birth Registry. BDs captured up to one month of age.	WT, 0–11 years, 1973–1984, Swedish National Cancer Registry	Five sex and birth month and year matched controls without cancers were selected for each case from the Medical Birth Register.
Linet et al., 1996 [63] (Sweden)	The National Medical Birth Register (ICD-8 codes 740–759)	Brain tumors, 0–17 years, 1973–1989, the National Cancer and Death Registers	Same as Lindblad et al., 1992 [81]
Case series studies with external comparison groups
Breslow et al., 1982 [83] (The National Wilms’ Tumor Study (NWTS))[110]	The NWTS registration form (ICD-9 codes 741–759)	WT, 0–15 years, 10/1969–3/1981, the NWTS Statistical Center; histologic confirmation was available for 75% of the patients	Survey findings were compared to the CPP and results from the CDC Surveillance system on BDs.
Ruymann et al., 1988 [87] (Ohio, U.S.)	Autopsy reports (major and minor ascertained)	RMS, NR, NR, Autopsy results from children in the Intergroup Rhabdomyosarcoma Studies I and II	Rates were compared with those from the NWTS and the CPP.
Narod et al., 1997 [53] (United Kingdom)	A postal questionnaire to family physicians of children diagnosed with cancer and who were alive at the end of 1988 (ICD-9 codes 7400–7599)	Leukemia, lymphoma, brain and spinal cord, NB, RB, WT, liver, OS, ES, STS, gonadal and germ cell, 0–14 years, 1971–1986, National Registry of Childhood Tumors	The expected number of cancer cases was calculated based on two groups: 1) the frequency of BDs among children in the study group, and 2) the frequency of BDs recorded in the British Columbia Health Surveillance Registry (BC Registry).