Validez del consumo declarado de tabaco en el embarazo

Objetivos

Analizar la relación entre el consumo de tabaco declarado por las embarazadas que declaran fumar antes de la gestación y los niveles de cotinina en orina al inicio y al final de la gestación.

Diseño

Estudio observacional, longitudinal.

Participantes Grupo de estudio

147 gestantes que acuden a primera visita de control prenatal a consultas externas del Hospital del Mar de Barcelona durante 1997. Grupo de control: 50 gestantes no fumadoras atendidas para control de embarazo durante 1997.

Mediciones

Número de cigarrillos que declaran fumar al día en la primera visita de control en nuestro centro y en la última visita antes del parto. Niveles de cotinina en las orinas aportadas a dichas visitas.

Resultados

La media de cotinina en las gestantes que declaran haber dejado de fumar es superior a la de las no fumadoras. Existe una relación lineal estadísticamente significativa entre el número de cigarrillos declarados y los niveles de cotinina en la primera visita y en la última visita de control gestacional, así como entre la variación de número de cigarrillos y niveles de cotinina entre ambas visitas. El valor predictivo negativo de la declaración del habito tabáquico es del 82,9%.

Conclusiones

Se observa cierto grado de infradeclaración entre las gestantes fumadoras, si bien hay una buena correlación entre declaración de consumo y niveles de cotinina. La infradeclaración no aumenta a pesar del consejo reiterado para dejar de fumar, por lo que, a pesar de sus limitaciones, puede ser un indicador útil para evaluar el efecto de las intervenciones orientadas a promover el abandono del tabaquismo durante la gestación.

Objectives

To analyse the relationship between the stated consumption of tobacco by pregnant women who say they smoked before pregnancy and the levels of cotinine in their urine at the start and end of pregnancy.

Design

Observational, longitudinal study.

Participants

During 1997. Study group: 147 pregnant women at their first pre-natal visit to outclinics of the Hospital del Mar. Control group: 50 non-smoker pregnant women monitored during their pregnancy.

Measurements and main results

The numbers of cigarettes per day that they said they smoked on their first monitoring visit to our centre and at the last attendance before giving birth were recorded. Cotinine levels in the urine samples taken on these visits were measured. Mean cotinine in pregnant women who said they had given up smoking was higher than in nonsmokers. There was a statistically significant linear relationship between the number of cigarettes stated and cotinine levels at the first and last pregnancy monitoring visits, as well as between the variation in the number of cigarettes and cotinine levels at these two visits. The negative predictive value of what they said about their tobacco habit was 82.9%.

Conclusions

There was a certain under-declaration by pregnant smokers, although their statements of consumption and cotinine levels correlated closely. The under-declaration did not increase despite reiterated advice to stop smoking, which means that, despite its limitations, it could be a useful indicator for evaluating the effect of interventions aimed at stopping women smoking during pregnancy.