Study Methods Subject characteristics Exposure and control used in the present review Gestational diabetes mellitus definition  Adjusted confounders in the present review Notes
a ̵́ Rogvi 2012
Design: retrospective cohort Setting: population-based Location: Denmark Sample size: 116,595 Age: 24.7 ± 2.8 Birth year: 1978 to 1981 Ethnicity: not reported Smoking: not reported Primiparous: not reported Exposure: gestational age <37 weeks (n = 1329) Control: gestational age ≥37 weeks (n = 31,047)
GDM defined by ICD-8: 634.74 or ICD-10: O24.4
Unadjusted
Published data only
Andraweera 2019
Design: prospective cohort Setting: hospital-based (multicentre) Location: international Sample size: 5,327 Age: 28.7 ± 5.4 Birth year: not reported Ethnicity: non-Hispanic White, Asian, Polynesian, Indian, others Smoking: 566 (10.1) Primiparous: 5327 (100) Exposure: birth weight of <2500g (n = not reported) Control: birth weight of ≥2500g (n = not reported)
GDM defined by fasting glucose ≥ 5.1 mmol/L or a 2-hour level of ≥ 8.5 mmol/L following an oral glucose tolerance test, according to the new WHO classification
Maternal age, smoking at 15 weeks’ gestation, ethnicity, socioeconomic status, family history of diabetes, maternal gestational age at birth, infant sex, and recruitment centre.
Unpublished and published data
Bo 2003
Design: case control Setting: hospital-based (single centre) Location: Italy Sample size: 300 Age: not reported Birth year: not reported Ethnicity: not reported Smoking: 100 (33.3) Primiparous: not reported
Birth weight as a continuous variable
GDM defined by fasting glucose ≥ 95 mg/dl, a 2-hour level of ≥ 155 mg/dl, or a 3-hour level of ≥ 140 mg/dl. Impaired glucose tolerance defined that only one glucose value was higher than above cut-off levels.
Maternal diabetes
Published data only
Boivin 2012
Design: retrospective cohort Setting: population-based Location: Canada Sample size: 24,119 Age: Preterm, 23.1 ± 3.7; Term 23.4 ± 3.8 Birth year: 1976 to 1995 Ethnicity: not reported Smoking: not reported Primiparous: 12,130 (50.3) Exposure: gestational age of 32 to 36 weeks (n = 6851) Control: gestational age of 37 to 42 weeks (n = 16,714)
GDM defined by ICD-9 before April 1, 2006, and the ICD-10 after April 1, 2006.
Mother’s birth characteristics (SGA, large for gestational age, multiple births, and year of birth), chronic hypertension, diabetes, kidney disease, age ≥ 25 years and multiple-birth pregnancy.
Unpublished and published data
Chawla 2014
Design: retrospective cohort Setting: population-based Location: US Sample size: 130,617 Age: mainly 25 to 35 Birth year: 1956 to 1976 Ethnicity: non-Hispanic White, Hispanic, and African Smoking: not reported Primiparous: 60,958 (46.7) Exposure: SGA (n = 13,934) Control: AGA (n = 116,658) Diabetes during pregnancy defined as pre-existing DM (including monogenic, Type 1 and Type 2) and gestational DM.
Maternal age, education, parity, plurality, marital status, and race/ethnicity
Published data only
Crusell 2017 Design: case control Setting: hospital-based (single centre) Location: Denmark Sample size: 1,322 Age: mainly 26 to 28 Birth year: 1939 to 1970 Ethnicity: not reported Smoking: not reported Primiparous: not reported Birth weight as a continuous variable GDM based on local criteria and changed during the period: until 1987 a 3 h 50 g OGTT, and after 1987 a 3 h 75 g OGTT. GDM was diagnosed when two or more out of seven measurements exceeded the mean +3 standard deviations on a curve based on non-pregnant normal-weight women without a family history of diabetes Unadjusted Published data only
Egeland 2000
Design: retrospective cohort Setting: population-based Location: Norway Sample size: 138,714 Age: 14 to 31 Birth year: 1967 to 1984 Ethnicity: not reported Smoking: not reported Primiparous: not reported Exposure: birth weight of <2500g (n = 4,652) Control: birth weight of 4000 to 4500g (n = 14,852)
Self-reported GDM in one or more pregnancies
Women’s age and parity and their mother’s diabetic status.
Published data only
Innes 2003
Design: case control Setting: population-based Location: USA Sample size: 23,395 Age: mainly 17 to 24 Birth year: 1970 or later Ethnicity: White, non-Hispanic, Hispanic, other non-White Smoking: 4,258 (18.2) Primiparous: 23,395 (100) Exposure: birth weight of 2000 to 2499 g (n = 1325) Control: birthweight of 3500g to 3999 g (n = 5639)
GDM defined by ICD-9 code 648.0 or abnormal glucose tolerance defined by ICD-9 code 648.8 on their hospital discharge records.
Age, race, education, employment status, pre-pregnancy body mass index, height, pregnancy weight gain, and gestational age,
Published data only
Legarros 2012
Design: retrospective cohort Setting: population-based Location: Sweden Sample size: 323,083 Age: mainly 20 to 29 Birth year: 1973 or later Ethnicity: not reported Smoking: 43,397 (13.4) Primiparous: 196,859 (60.9) Exposure: SGA defined as more than 2 SD below the mean birth-weight-for-gestational-age (n = 12,083) Control: Birth weight 1 SD below the mean to 1 SD above the mean (n = 214,905)
GDM defined by the ICD-9 code 648W and the ICD-10 code O244, those diagnosis were mainly based on a 75 g oral glucose tolerance test with a fasting capillary whole blood glucose level C 6.1 mmol/L (plasma C 7.0 mmol/L) and/or a 2 h blood glucose C 9.0 mmol/L (plasma glucose C 10.0 mmol/L)
Body mass index height, maternal age, education, parity, smoking, and year of pregnancy
Published data only
Moses 1999 Design: case control Setting: hospital-based (single centre) Location: Australia Sample size: 138 Age: case, 26 (5.8); control, 26 (5.6) Birth year: not reported Ethnicity: not reported Smoking: not reported Primiparous: not reported Birth weight as a continuous variable GDM defined by fasting glucose is ≥5.5 mmol/l and/or the 2-h glucose level is ≥8.0 mmol/l, according to the criteria of the Australasian Diabetes in Pregnancy Society. Unadjusted Published data only
Ogonowski 2014
Design: case control Setting: hospital-based (multicentre) Location: Poland Sample size: 1,588 Age: 29.7 (0.6) Birth year: not reported Ethnicity: Caucasian Smoking: not reported Primiparous: 902 (56.8) Exposure: birth weight of < 2500g (n = not reported) Control: birth weight of 3500 to 3999g (n = not reported)
GDM defined by either the fasting glucose was 7.0 mmol/L or the 2-h glucose concentration was 7.8 mmol/L, which was in accordance with the WHO diagnostic criteria
Age, body mass index, family history of diabetes, and prior gestational diabetes.
Published data only
Olah 1996
Design: retrospective cohort Setting: hospital-based (single centre) Location: UK Sample size: 592 Age: 27 (range 19 to 42) Birth year: not reported Ethnicity: predominantly Caucasian Smoking: not reported Primiparous: not reported Exposure: birth weight of <2500g (n = 57) Control: birth weight of ≥ 2500g (n = 452)
Impaired glucose tolerance, defined as a 2-hour plasma glucose concentration of 7.8-1 1.0 mmol/L, or gestational diabetes, defined as a 2-hour plasma glucose concentration of 11.1 mmol/L or more.
Unadjusted
Published data only
Pettit 1998
Design: retrospective cohort Setting: not reported Location: US Sample size: 831 Age: not reported Birth year: not reported Ethnicity: Pima Indians Smoking: not reported Primiparous: not reported Exposure: birth weight of <2500g (n = 29) Control: birth weight of ≥2500g (n = 802)
Diabetes during pregnancy diagnosed by the WHO criteria, i.e., a glucoses concentration of ≥ 11.1 mmol/L 2 h after the ingestion of a 75-g glucose load
Unadjusted
Published data only
Plante 1999
Design: retrospective cohort Setting: population-based Location: US Sample size: 6,767 Age: 19 to 22 Birth year: 1974 Ethnicity: non-Hispanic White, African Smoking: not reported Primiparous: not reported Exposure: SGA defined as a birth weight less than the tenth percentile for gestational age, race-specific for either black or white (n = 596) Control: not SGA (n = 5,954)
Diabetes on the birth certificate records. The coding was performed by the physician or other individual filling out the birth record and consisted of a checkbox in the field described as “medical complications of pregnancy.”
Unadjusted
Published data only
Plante 2004
Design: retrospective cohort Setting: population-based Location: US Sample size: 7,802 Age: 24 to 26 Birth year: 1974 Ethnicity: non-Hispanic White, African Smoking: not reported Primiparous: not reported Exposure: SGA as defined in the Plante 1999 study (n = 537) Control: AGA as defined in the Plante 1999 study (n = 7,265)
Diabetes on the birth certificate. Specific information as to criteria for diagnosis was not available
Unadjusted
Published data only
Savona-Ventura 2003
Design: case control Setting: hospital-based (single centre) Location: Malta Sample size: 7,075 Age: not reported Birth year: 1952 to 1983 Ethnicity: not reported Smoking: not reported Primiparous: not reported Exposure: birth weight of <2500g (n = 419) Control: birth weight of ≥2500g (n = 6,656)
GDM defined by a serum glucose concentration >8.6 mmol/l 2 hours after the OGTT.
Unadjusted
Published data only
Seghieri 2002
Design: retrospective cohort Setting: hospital-based (single centre) Location: Italy Sample size: 604 Age: LBW: 31.7 (4.2)) Birth year: not reported Ethnicity: not reported Smoking: not reported Primiparous: not reported Exposure: birth weight of <2500g (n = 68) Control: birth weight of ≥2500g (n = 536)
GDM defined by the American Diabetes Association
Age, parity, family history of diabetes, and pre-pregnancy BMI,
Published data only
Williams 1999
Design: retrospective cohort Setting: population-based Location: US Sample size:41,839 births (38,513 mothers) Age: mainly 19 to 29 Birth year: 1949 to 1979 Ethnicity: non-Hispanic White, Hispanic, African, native American Smoking: 10,429 (24.9) Primiparous: 32,488 (77.7) Exposure: birth weight of <2500g (n = 2,708 births) Control: birth weight of ≤2500g (n = 39,131 births)
GDM recorded on the birth certificate and/or given an ICD-9 diagnosis
Unadjusted
Published data only
Data are presented as the mean ± SD or number (percentage). GDM, gestational diabetes mellitus, ICD, International Classification of Diseases; WHO, World Health Organization; SGA, small for gestational age; AGA, appropriate for gestational age; SD, standard deviation; OGTT, oral glucose tolerance test Data are presented as the mean ± SD or number (percentage). GDM, gestational diabetes mellitus, ICD, International Classification of Diseases; WHO, World Health Organization; SGA, small for gestational age; AGA, appropriate for gestational age; SD, standard deviation; OGTT, oral glucose tolerance test Data are presented as the mean ± SD or number (percentage). GDM, gestational diabetes mellitus, ICD, International Classification of Diseases; WHO, World Health Organization; SGA, small for gestational age; AGA, appropriate for gestational age; SD, standard deviation; OGTT, oral glucose tolerance test Data are presented as the mean ± SD or number (percentage). GDM, gestational diabetes mellitus, ICD, International Classification of Diseases; WHO, World Health Organization; SGA, small for gestational age; AGA, appropriate for gestational age; SD, standard deviation; OGTT, oral glucose tolerance test Data are presented as the mean ± SD or number (percentage). GDM, gestational diabetes mellitus, ICD, International Classification of Diseases; WHO, World Health Organization; SGA, small for gestational age; AGA, appropriate for gestational age; SD, standard deviation; OGTT, oral glucose tolerance test Data are presented as the mean ± SD or number (percentage). GDM, gestational diabetes mellitus, ICD, International Classification of Diseases; WHO, World Health Organization; SGA, small for gestational age; AGA, appropriate for gestational age; SD, standard deviation; OGTT, oral glucose tolerance test Data are presented as the mean ± SD or number (percentage). GDM, gestational diabetes mellitus, ICD, International Classification of Diseases; WHO, World Health Organization; SGA, small for gestational age; AGA, appropriate for gestational age; SD, standard deviation; OGTT, oral glucose tolerance test