Det vides, at IgG krydser placentabarrieren, og Avastin forventes at hæmme angiogenesen hos fostret og er dermed under mistanke for at kunne forårsage alvorlige medfødte misdannelser ved indgivelse under graviditet.
IgGs are known to cross the placenta, and Avastin is anticipated to inhibit angiogenesis in the foetus, and thus is suspected to cause serious birth defects when administered during pregnancy.