a) Changes in the skin

Alterations in hormonal balance and mechanical stretching are responsible for several changes in the integumentary system. Accordingly, the following changes occur profusely in the skin during pregnancy.

• Linea Nigra: this is a hormone induced dark line (pigmentation) that runs from the umbilicus to the symphysis pubis and may extend up to the sternum. After delivery, the line will fade away, though it may not completely disappear.
  
• Mask of pregnancy (Chloasma): this is the hyper brownish pigmentation of the skin (bronze look in dark women) over the face and forehead. It begins about the 16th week of pregnancy and gradually increases. It usually fades away after delivery.
  
• Striae Gravidarum (Stretch Marks): this happens due to the action of the Adrenocorticosteroid hormone. It reflects a separation within underlying connective tissue of the skin. This occurs over areas of the maximal stretch (e.g.the abdomen, thighs, and breasts). It will usually fade away after delivery although they don't completely disappear.
  
• Sweat glands: the activity of the sweat glands throughout the body usually increases causing the woman to perspire more profusely during pregnancy.

b) Changes in the breasts. 

In early pregnancy, the breast may feel full or tingle, and increase in size as pregnancy progresses. The areola of the nipples darkens and the diameter increases. The Montgomery's glands (the sebaceous glands of the areola) enlarge and tend to protrude.

The surface vessels of the breast may become visible due to increased circulation and turns to a bluish tint to the breasts. By the 16th week (2nd trimester) the breasts begin to produce colostrum. This is the precursor of breast milk. It is a thin, watery, yellowish secretion that thickens as pregnancy progresses. It is extremely high in protein.