During pregnancy, the amount of blood in the body increases, causing the mucous membranes to swell, become thicker and even bleed more easily. The mucous membranes in your nose, mouth and vagina are affected.
For example, you may suffer from a stuffy nose or nosebleeds. If your nose is congested, use a saline nasal spray. This is preferable to over-the-counter nose drops that can actually make the problem worse if used more than one week. Many pregnant women suffer for several months which is why saline is preferable (the other drops are good for a shorter cold, for example).
The swelling in your nose often becomes worse when you lie down, and it is common to snore more during pregnancy. Try elevating your head with a couple of extra pillows if you have problems with snoring.
Source: - Lärobok för barnmorskor. Faxelid, E. Course literature 2001. - Myles Textbook for Midwives. Fraser, D. och Cooper, M. Churchill Livingstone 2003.