Table 1 Characteristics of the studies included in this meta-analysis
The first author’s name | Year of publication | Research design | Outcome | Study population | % of males among cases | Maternal age (years) | Area | Diagnostic criteria | Data source | Time of exposure | Smoking category | Adjustment variables | Quality assessment score |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Mathews, C. A | 2014 | Cohort | TS | No. of TS/total study population: 50/6,090 | - | - | Avon,UK | DSM-IV-TR | Maternal questionnaires | In the last 2Â months of pregnancy | Any smoking | Maternal age, parity, socioeconomic status level, pregnancy complications, alcohol and cannabis use in the last 2Â months of pregnancy | 9 |
Leivonen, S | 2016 | Nested case–control | TS | No. of maternal smoking/No. of controls: 356/2,698 No. of maternal smoking/No. of TS cases: 121/723 | 84.2 |  < 20y:72 20–29y:1,386 30–39y:1,169  ≥ 40y:71 | Finland | ICD-10, ICD-9 | A medical birth register | During pregnancy | Smoking during the first trimester only, and smoking throughout the pregnancy | Maternal and paternal psychiatric history, maternal and paternal age, birth weight, gestational age, and maternal socioeconomic status | 8 |
Motlagh, M. G | 2010 | Case–control | TS | No. of maternal smoking/No. of controls: 1/62 No. of maternal smoking/No. of TS cases: 3/45 | 71.0 | 28.3 ± 4.1 | Yale,USA | DSM-IV-TR | Maternal interview | During pregnancy | More than 10 cigarettes in 24 h at any point in the pregnancy | Gender, severe psychosocial stress, low birth weight, > 1 hypoxic event | 6 |
Cubo, E | 2014 | Nested case–control | CTD | No. of maternal smoking/No. of controls: 21/89 No. of maternal smoking/No. of CTD cases: 25/64 | 70.0 | 30.41 ± 4.61 | Spain | DSM-IV-TR | Birth certificates | For the entire pregnancy | Any smoking | Family history of tics, neonatal respiratory distress syndrome, body mass index, prenatal infection, and coexisting comorbid neuropsychiatric disturbances | 7 |
Faebo Larsen, R | 2013 | Cohort | DCD | No. of DCD/total study population:1,001/33,354 | - |  < 25y:3,673 25–30y: 13,989 30–35y: 11,487  ≥ 35y: 4,205 | Denmark | DCDQ’07 | Maternal interview and the 7-year questionnaire | In the first trimester | Any smoking, 1 g– < 10 g/d, ≥ 10 g/d | Sex, gestational age, intrauterine growth restriction, maternal age, mother’s occupational status, alcohol consumption in the first trimester, and binge drinking in the first trimester | 8 |
Christensen, L. H | 2016 | Cohort | DCD | 1,023 | - | 25.18 | Greenland and Ukraine | DCDQ’07 | Structured interview questionnaire and telephone interviews | In the second or third trimester of pregnancy | Smokers were defined as women with serum cotinine concentrations > 10 ng/ml | Age of the mother and child, parity, sex, maternal educational level, maternal pre-pregnancy alcohol consumption and duration of breastfeeding | 7 |
Yang, Q | 2020 | Cross-sectional | DCD | 8586 | 61.5 | 19–25y: 237 26–30y: 1,870 31–35y: 3,858 36–48y: 1,621 | Shanghai, China | MABC-2 screening combined with the paediatrician’s confirmation | A questionnaire interview | During pregnancy | Smoking at least one cigarette every day for at least six months | Prenatal exposure of secondhand smoke and breastfeeding time | 9 |
Mahlberg, N | 2019 | Cross-sectional | DCD | 122 | 59.3 | - | Niagara, Canada | MABC-2 | Parent questionnaires | During pregnancy | Either active or passive maternal smoke exposure | Age, sex, birth weight, premature birth, and household income | 8 |