Rubella which is also known as German measles is an infection that is caused by a virus. Though it does not have severe effect like other measles but this is very harmful for pregnant ladies.
Sarah who is 7 weeks pregnant, if she has contracted this virus, this will pass on to her fetus and will cause severe damage to the fetus. Major problems like eye problems, ear problems, heart damage and other congenital problems will occur. The damage done to the fetus will last for a lifetime.
In the other case where Nadiya is 7 months pregnant, this will do no damage to her baby as in the last trimester this disease does not pass on to the baby.