Smoking habits, nicotine use, and congenital malformations.
OBJECTIVE
We examined whether maternal smoking and use of nicotine substitutes during the first 12 weeks of pregnancy increased the prevalence of congenital malformations in general and of certain congenital malformations in particular.


METHODS
In the Danish National Birth Cohort (1997-2003) we identified 76,768 pregnancies (and their subsequent singleton births); 20,603 were exposed to tobacco smoking during the first 12 weeks of pregnancy. Birth outcomes were collected by linkage to the Central Population Register, the National Patients Register, and the National Birth Register. We identified congenital malformations from the Hospital Medical Birth Registry as they were recorded at birth or in the first year of follow-up.


RESULTS
Smoking mothers were younger, weighed less, consumed more alcohol, and had received less education. Children exposed to prenatal tobacco smoking had no increase in congenital malformations prevalence compared with the nonexposed children in both crude and adjusted analyses. Children born to nonsmokers, but who used nicotine substitutes, had a slightly increased relative congenital malformations prevalence ratio; relative prevalence rate ratio was 1.61 (95% confidence interval 1.01-2.58), which represents a 60% increased risk. When the analysis was restricted to musculoskeletal malformations, the relative prevalence rate ratio was 2.63 (95% confidence interval 1.53-4.52).


CONCLUSIONS
Our results showed no increase in congenital malformations related to prenatal tobacco smoking. However, we identified an increase of malformations risk in nonsmokers using nicotine substitutes. This finding needs to be replicated in other data sources.


METHODS
II-2.
Morales-Suárez-Varela
María M
MM
Unit of Public Health and Environmental Care, Department of Preventive Medicine, University of Valencia, Valencia, Spain. maria.m.morales@uv.es
Bille
Camilla
C
Christensen
Kaare
K
Olsen
Jorn
J
D000328:Adult; D001294:Attitude to Health; D016001:Confidence Intervals; D000013:Congenital Abnormalities / Q000175:diagnosis / Q000453:epidemiology* / Q000209:etiology*; D003718:Denmark / Q000453:epidemiology; D004522:Educational Status; D005260:Female; D006801:Humans; D008423:Maternal Age; D018811:Maternal Exposure / Q000009:adverse effects*; D008875:Middle Aged; D009538:Nicotine / Q000009:adverse effects*; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D015995:Prevalence; D011336:Probability; D012042:Registries; D012189:Retrospective Studies; D012907:Smoking / Q000009:adverse effects* / Q000453:epidemiology; D012959:Socioeconomic Factors
D009538:Nicotine