Bustline Increases

My breasts feel very tender all the time

Though your breasts will continue to grow throughout your pregnancy, the tenderness will disappear after the 3rd or 4th month. As for sagging, that depends on you, as this is the result of lack of support during pregnancy. So it is essential to wear a good support bra, even at night.
 
My breasts are growing at an embarrassing rate

This is because your body is producing estrogen and progesterone in increasing amounts, making your breasts tender and swollen. All this indicates that your body is preparing itself to feed your baby when it arrives. The pigmented area (areola) around the nipple will darken and the sebaceous gland will become more prominent. The blue vein that appears forms a passage for nutrients and fluids to pass from the mother to the baby. Overall, your breasts could grow about 3 cup sizes.
 
I am worried about losing my figure after childbirth

The mother’s breasts usually do increase in size by as much as 2-5 inches during pregnancy and remain enlarged for a few months after delivery until the mother continues to nurse her baby. In addition to breasts, the uterus also expands in size during pregnancy.  Soon after delivery, however, it begins to contract to get back to its original size.  The stronger the abdominal muscles, the faster the uterus shrinks.  Any abdominal muscle toning exercises done during pregnancy and prior to getting pregnant will greatly improve the elasticity of the muscles and help in the uterus contracting back to its pre-pregnancy size.  In addition, contrary to popular belief, you are more likely to regain your figure if you breast-feed your baby.
 
Will my breasts sag with pregnancy or breastfeeding

Since there are no muscles in the breast, only ligaments, your breasts will sag from the increased weight unless well supported by a good-fitting bra.  These ligaments, once stretched, never return to their original size.  Therefore, a bra with good all-round support should be worn at all times, preferably even while sleeping at night.  The good news (or the bad news if you were flat-chested) is that your breasts will eventually shrink back almost to the pre-pregnancy size.