Paternal occupation and neural tube defects: a case-control study based on the Oxford Record Linkage Study register.

Certain paternal occupations and related exposures have been suggested as possible risk factors for neural tube defects (NTD). We analysed data collected as part of a case-control study to investigate the relationship between paternal occupational exposures and NTD. Cases were 694 NTD-affected pregnancies diagnosed between 1970 and 1987 in Oxfordshire or West Berkshire, England. Controls were randomly selected from a computerised maternity database individually matched to cases on maternal year of birth and year of index pregnancy. Data on paternal occupation were abstracted from hospital antenatal records. Associations between paternal occupational exposures and NTD were assessed using odds ratios adjusted for maternal year of birth, year of index pregnancy, gender of baby, multiplicity of birth and number of previous obstetric events. Statistically significant positive associations were observed for paternal occupational exposure to agrochemicals and animals. Analysis by occupational title revealed that more case than control fathers were farmers, gardeners and butchers. Statistically significant negative associations were seen for paternal occupational exposure to inhaled hydrocarbons and metal-working oil mists. The findings from this population-based study for paternal agricultural and animal-related occupations overlap and have been previously observed. The apparent protective effects of fathers working with inhaled hydrocarbons and metal-working oil mists have not been previously described. No underlying biological mechanisms have been identified, therefore other explanations cannot be excluded.