Yes, it's very common. Most babies arrive between 37 weeks and 41 weeks of pregnancy, usually within a week on either side of their expected due date (HSCIC 2015, NHS Choices 2015) . On the flip side, it's very common for twins, and particularly triplets, to arrive before 37 weeks of pregnancy (NCCWCH 2011) .ccording to research, only about one in 25 (four per cent) of babies are born on their exact due date (Mongelli 2014) . About one in five babies are born at 41 weeks or after (HSCIC 2015) . So rest assured, you’re not alone in wondering when your baby will make an appearance!