Sex during pregnancy?

With my last visit to my doctor she give me a medicine call Progesterone I'm 24 weeks and I had my fist baby prematurely( 31 week)... anyways she said not to have sex until 26 or 36 weeks... (I get confused because she said "26 weeks so that about 12 week")

any of you with the same problem? is it bad to have sex for one night and then introduce the pill?

Update****

Thanks girls I talk to him this morning before taking him to work and I tell him my plans last night of surprising him while he sleep but he said not to worry about him that he understand and tht he love his family so much he haven't think on pushing me to have sex n we will have time for that... I guess he want Jr. to be good...