Contact with pregnant women is allowed at least four weeks after iodine 131 treatment.
Iodine 131 treatment is a radioactive treatment that lasts about 1 week. Radioactive iodine 131 has a definite half-life and usually takes about 1 week to decay to half the intake.
The longer you receive Iodine 131 treatment, the more radiation you receive and the longer you have to wait for it to be metabolized. Therefore, in order to avoid affecting the health of others after iodine 131 treatment, you should keep a safe distance from people, and pay special attention to avoid contact with pregnant women and infants in the short term. After about 4 weeks, the amount of iodine 131 radiation has decayed completely, so you can have contact with pregnant women.