Influence of smoking and socioeconomic status on labor analgesia: a nationwide register-based study in Finland.

Purpose: Labor pain can be treated by medical and non-medical analgesia. Smoking during pregnancy has been shown to increase the incidence of several complications and may influence analgesic effectiveness. Previous studies have linked socioeconomic status to the use of epidurals for labor analgesia. We aimed to determine whether smoking and socioeconomic status influence the use of labor analgesia in Finland.

Methods: From January 1, 2004 to December 31, 2018, we collected data from the national Finnish Medical Birth Register on smoking status, labor analgesia, and socioeconomic status during pregnancy. These categorized variables were presented as absolute numbers and percentages. We included data on singleton pregnancies and excluded any data on pregnancies that missed smoking or socioeconomic status.

Results: 71,603 women smoked during the first trimester, 42,079 women continued to smoke after the first trimester, and 641,449 were non-smokers. The four most used labor analgesia were nitrous oxide, epidural, other medical analgesia, and non-medical analgesia. The most frequently used analgesia was nitrous oxide, which was used by 60.8% of the group of smokers after the first trimester, 58.8% of smokers during the first trimester, and 54.5% of non-smokers. There were no substantial differences between socioeconomic status classes and labor analgesia used.

Conclusion: Women who continued smoking after the first trimester used labor analgesia more often than non-smokers. There were no clear differences between socioeconomic status classes and labor analgesia used. These findings highlight the need to reduce maternal smoking during pregnancy, and universal social healthcare systems should promote equality in labor analgesia.