With the life inside you growing every day, your uterus has also grown and now is about the size of a melon. Many professionals feel this week marks a lower incidence of miscarriage, and many moms-to-be find it easier to start telling friends and family now that the 12th week has passed. You'll also likely notice an increase in your energy levels and sex drive around this time thanks to hormone changes.
As your pregnancy progresses, you'll have extra estrogen that can stimulate melanocytes which produce skin pigment and can cause darkening of your skin. This darkening can appear as the "line of linea nigra" that stretches down the abdomen, darker areola, and nipples, or a mask-like darkening around your eyes and across the cheeks known as the "mask of pregnancy." All of these changes in skin color are considered normal and usually fade after your baby is born.
In the second trimester, you'll gain somewhere around 13-14 pounds, which means maternity clothes shopping is likely a must depending on your lifestyle. Buying a few staples early can mean a longer wear time and fewer expenses down the line.
- American Pregnancy Association - Week 13