Pregnancy 3 months after the C14 is done generally has no effect on the fetus, but it is recommended to visit your obstetrician for evaluation and determination.
C14 is a radiolabel with some radioactivity, but the amount of radiation is very small and generally safe for the general population. However, the C14 test is currently not clinically indicated for children under 12 years of age, pregnant women and nursing mothers, and it is generally recommended to choose the safer C13.
Most of the C14 urea capsules taken orally will be metabolized within 72 hours, so the effect of C14 radioactivity on pregnancy after 3 months is already very small. However, there are more factors affecting pregnancy, so it is recommended to complete the prenatal checkups in time to be evaluated by the obstetrician to determine if there is any effect on the fetus.