Your baby would fit into your palm this week and fatty deposits are starting to be laid down under the skin ready to help your baby maintain his body temperature once he is born. Connections are happening all the time between his brain, his muscles and nervous system and his tiny heart is busy pumping about 42 pints of blood everyday!
You may start to notice considerable changes in your breasts this week, such as swelling and increasing by a cup size, or a more veiny appearance. The areola, or area around your nipple and your nipple will start to get darker as well as increasing in size.
A line may appear from your belly-button down your navel this week which is know as the linea nigra and will continue to darken throughout your pregnancy, then vanish once you have had your baby!
The reason for breast changes is that your body is getting ready for breastfeeding. You might notice your areola (the area around your nipple) darkening and little bumps appearing as your breasts increase in size. In addition, veins in your breasts may suddenly become particularly pronounced.
None of these changes are permanent and breast tenderness is not likely to last past the fourth month, when your hormones will stabilise a bit more; although it is possible that they will feel different for the rest of the pregnancy.
Make sure you wear a good support bra, and if you are worried about stretch marks, massage sweet almond-based oil into your skin daily. Both of these things may well help your breasts stay more pert after pregnancy. In the early stages there is not much that you can do to decrease breast tenderness, but be assured that your hormones will balance out and your breasts won't feel this sensitive for ever.
It is best to stop wearing underwired bras in pregnancy because the wire could affect the delicate changes taking place inside your breasts. By the time you reach the sixth week of pregnancy, your breasts may already have started to change shape and size, so it's best to invest in one or two non-underwired, comfortable and supportive bras. You may want to consider getting your breasts measured for a maternity bra. Of course, it's impossible to predict how big your breasts will actually get before you have your baby (and, indeed, afterwards if you plan to breastfeed) so you may need to be measured two or three times during your pregnancy.