| Dollberg 200091 | | Selected term infants who were appropriate for gestational age by intrauterine growth charts |
| Eskenazi 199592 | | Non-ETS exposed women could have smoking spouses |
| Gomez 200593 | | Cannot separate active and passive smokers |
| Greider 199894 | | Full text copy impossible to locate through interlibrary loans |
| Jaakkola 200195 | | Non-ETS exposed women could have smoking spouses |
| Jadsri 199596 | | Cannot distinguish between smoking and non-smoking mothers |
| MacArthur 198797 | | Recruited only ex-smoking pregnant women in sample |
| Magnus 198498 | | Cannot distinguish between smoking and non-smoking mothers |
| Rubin 198699 | | Cannot distinguish between smoking and non-smoking mothers |
| Terris 1969100 | | Cannot distinguish between smoking and non-smoking mothers |
| Ueda 1989101 | | Standardised measure called relative birth weight (expressed as %), but no numbers given to extract |
| Underwood 1967102 | | Cannot distinguish non-smoking mothers and whether fathers smoked |
| Yerushalmy 1971103 | | Cannot separate mothers smoking status from fathers |