OBJECTIVE: To study the association between maternal working conditions and low birth-weight in Mexico City. MATERIAL AND METHODS: Interviews of 2623 workers who gave birth in Mexico City hospitals during 1992 were analyzed. Information on the main biologic and social factors associated to low birth-weight was registered. Occupational stress was determined with the instrument designed by Karasek. Logistic regression models to evaluate the relationship between working conditions and low birth-weight were used, controlling by confounding variables. RESULTS: Low birth-weight was more frequent in workers with working periods of more than 50 h/week (OR = 1.6; 95% CI = 1.17, 2.28) and with problems at work (OR = 1.5; 95% CI = 1.0, 2.25). Lack of tangible social support was identified as a risk factor for low birth-weight (OR = 1.7; 95% CI = 1.20, 2.33). Preventive working measures such as changes in tasks, shortening of working hours and leaves of absence due to illness did not show a beneficial effects on birth-weight, except for the maternity leave of absence. Mothers with no right to this had a 2.2 higher probability of giving birth to low weight children (95% CI = 1.66, 2.93). CONCLUSIONS: These results emphasize the importance of identifying the occupational risk factors during pregnancy.
OBJECTIVE: To study the association between maternal working conditions and low birth-weight in Mexico City. MATERIAL AND METHODS: Interviews of 2623 workers who gave birth in Mexico City hospitals during 1992 were analyzed. Information on the main biologic and social factors associated to low birth-weight was registered. Occupational stress was determined with the instrument designed by Karasek. Logistic regression models to evaluate the relationship between working conditions and low birth-weight were used, controlling by confounding variables. RESULTS: Low birth-weight was more frequent in workers with working periods of more than 50 h/week (OR = 1.6; 95% CI = 1.17, 2.28) and with problems at work (OR = 1.5; 95% CI = 1.0, 2.25). Lack of tangible social support was identified as a risk factor for low birth-weight (OR = 1.7; 95% CI = 1.20, 2.33). Preventive working measures such as changes in tasks, shortening of working hours and leaves of absence due to illness did not show a beneficial effects on birth-weight, except for the maternity leave of absence. Mothers with no right to this had a 2.2 higher probability of giving birth to low weight children (95% CI = 1.66, 2.93). CONCLUSIONS: These results emphasize the importance of identifying the occupational risk factors during pregnancy.