Most women will find that they are much more comfortable if they start wearing maternity clothing at about four months. Because every woman is different though, the time to buy maternity clothes will vary a great deal. There are women who at twelve weeks say their regular pants are too tight so they started buying maternity clothing so that they were more comfortable, especially sitting down. In general, though, you will probably want to start shopping for maternity clothes during the third month of your pregnancy.
The one drawback to buying maternity clothing too soon is that you may not be happy with the fit by the time you reach your third trimester. The average woman is expected to gain about 2 to 4 pounds during the first three months of pregnancy and after that you can expect to pick up about a pound each week for a total weight gain of 25 to 35 pounds. The weight gain will determine when you need to start shopping for maternity clothing and you will know when your regular clothes get too tight.
When you go to shop for maternity clothing you can expect to buy the same size that you wear now. If you are currently a size 8 you will still be a size 8 in maternity wear; the clothes are just made differently to accommodate your changing shape. The biggest changes you will notice in your body occur about week 14 as the uterus moves higher and your abdomen becomes rounder, by week 16 the waist line usually disappears and you will have to start wearing maternity clothing. If you are carrying twins or triplets these changes will start to occur sooner and you will need to buy maternity clothes earlier.
While it may seem like a good idea to put off the purchase of maternity clothes as long as possible to spare the expense of a new wardrobe, it is important during your pregnancy that you are comfortable. You probably have a few loose fitting shirts or sweaters that will do but eventually you are going to need to buy some clothes that fit your new shape. Purchasing maternity clothing doesn't have to be as expensive as you might think. Since they are only worn for a short time, maternity clothing is excellent to purchase second hand.