Sex in the Last Trimester
As long as your pregnancy has progressed normally, you should still be able to have sex in your last months, provided you're not carrying multiples. Despite all the myths, no link has been established between preterm labor and sex in the last trimester. Lying flat on your back at this late stage in pregnancy, though, is not a good idea. Talk to your doctor or midwife about positions that are still safe.
Finally, once your water breaks you should not engage in intercourse or insert anything into the vagina, as this could cause infection.
Source: American College of Obstetricians and Gynecologists
All content here, including advice from doctors and other health professionals, should be considered as opinion only. Always seek the direct advice of your own doctor in connection with any questions or issues you may have regarding your won health or the health of others.