Although women vary in how much extra weight they carry through pregnancy, especially if they were under- or overweight before they get pregnant, there is an average pregnancy weight gain range which can be a useful reference to judge how you are doing.
Weight gain when expecting more than one baby
Not only does carrying an extra baby itself add to your weight gain, there is also likely to be additional amniotic fluid and placenta to factor in. This extra weight is something else that, whilst not neccessarily a cause for concern, is something you should bear in mind when looking ahead at your pregnancy with twins.
During pregnancy it is important not to starve yourself for fear of getting 'too fat'. Putting on some weight is a good idea if you are eating a well-balanced and nutritional diet. However, over-eating as a comfort - too many cakes, for example! - might mean you put extra strain on your back and the rest of your body.
If you were of a reasonable weight before your pregnancy, expect to put on 15 to 20kg over the course of the pregnancy (mostly in the second and third trimesters). If you were overweight beforehand, you might not put on as much weight (cutting back on creamy cheese etc, and other excesses like alcohol and fizzy drinks, which aren't good in a healthy pregnancy diet anyway, should help reduce the calories).
If you or your midwife team are concerned - by too much or too little weight gain - this will be discussed, as your weight is taken at each check-up.
But remember that pregnancy is a time for looking after yourself but not punishing yourself! If you are a little overweight, the best thing to do is make sure your current diet is well-balanced and that you feel healthy in yourself - don't let anyone make you feel bad for being big, just make sure you're well!
If you are expecting twins or more in a multiple pregnancy, check out the website of TAMBA, The Twins and Multiple Births Association for useful advice and support.