P06 Paternal exposure to methotrexate and the risk of miscarriage – a register based nationwide cohort study

ObjectiveTo study the association between paternal exposure to methotrexate within three month before conception and during the first trimester of pregnancy and the risk of miscarriage.MethodsWe conducted a nationwide cohort study identifying all registered pregnancies in Denmark from 1997 to 2015. All births were identified using the Medical Birth Registry, and all records of induced abortion and miscarriage were from the National Hospital Register. Data on drug use were from the National Prescription Register. Cox proportional hazard regression models were used to calculate the hazard of miscarriage in women with a partner exposed to methotrexate. The study was approved by the Danish Data Protection Agency (2015-41-4309).ResultsWe identified 1,364,063 registered pregnancies with known paternity, of whom 520 fathers were exposure to methotrexate within the three months before conception to the end of the first trimester. Among these, 46 (8.9%) experienced a miscarriage compared to 122,926 (9.0%) among the unexposed.There was no increased risk of experiencing a miscarriage in pregnancies to men exposed to methotrexate before pregnancy compared to unexposed (adjusted hazard ratio 0.99 (CI95% 0.67- 1.46)). Furthermore, we found no increased risk of experiencing a miscarriage in pregnancies to men exposed to methotrexate during first trimester compared to unexposed (adjusted hazard ratio 0.90 (CI95% 0.61–1.32)).ConclusionWe found no association between paternal exposure to methotrexate before and during early pregnancy and miscarriage. Available data suggest that paternal methotrexate exposure should not be of major concern. Multinational recommendations could be changed accordingly.Disclosure(s)Nothing to disclose