Fully normal lah, especially during pregnancy, hormones go crazy and make everything more sensitive, so sneezing at night is super common! A few of us first-time mums were also paranoid about this, but our gynae said as long as it's just sneezing and not accompanied by fever or other symptoms, it's nothing to worry about. The air at night time can be drier in our Malaysian homes (especially if got air cond), and pregnancy makes your nasal passages swell easier, so that's why you might sneeze more. If it's really bothering you, try keeping a humidifier in the room or just do some saline rinses, works wonders!