Belly changes during pregnancy week by week
weeks 0-6: in the first six weeks weeks of pregnancy you will not look pregnant and you may not be feeling pregnant, yet your body is already undergoing major changes in response to a massive surge in pregnancy hormones that started immediately after conception
weeks 6-10: your uterus will grow significantly in size. By eight weeks it is the size of a medium orange. It cannot be felt through your abdominal wall because it is still behind your pubic bone.
weeks 10-13: your waist will probably have thickened slightly and you will have on a little weight. Your tummy may be starting to swell too, but this is likely to be due to mild bloating and sluggish bowels than to your growing baby.
weeks 13-17: Nevertheless, during these weeks you will be conscious of the fact that you are starting to "show" and that work colleagues and friends who are not in the know are starting to look quizzically at your abdomen.
weeks 17-21: weight increases gradually, you will gain 1-2 lb per week on average , and by week 21 you will definitely look pregnant
weeks 21-26: your uterus will rise above your belly button. The stomach and other digestive organs become compressed and progesterone continues to relax the muscles in the gut.
weeks 26-30: you will notice that your abdomen is enlarging both upward and sideways
weeks 30-36: the height of the fundus measured in cm will be about the same as the stage of your pregnancy in weeks. This changes slightly when the baby's head descent and causes the height of the fundus to drop slightly in most pregnancies
weeks 35-40: if your baby's head has started to engage, your bump will appear to be lying lower in your abdomen cavity. There is something quite a noticeable change in your body shape and you may hear people remarking that you have :started to drop".