Most anti-TNF medications are monoclonal antibodies of the IgG class. For that reason these antibodies are, from around week 14 of gestation, actively transported across the placenta. When used into third trimester of pregnancy, higher levels of these TNF-alpha antibodies are reached in the fetal circulation compared to the maternal circulation, making the newborn more prone for infections. Vaccination of newborns with live inactivated vaccines are therefore contraindicated till anti-TNF alpha antibody levels are not detectable anymore. It is often advised to stop anti-TNF in the first trimester of pregnancy. The rationale behind this approach is that RA improves during pregnancy anyway and that it is safe to taper off medication. In addition it is thought that with discontinuation of anti-TNFearly during pregnancy no placental transfer of anti-TNF antibodies will take place. However, currently no scientific evidence is available to support both assumptions.