For at least the six weeks into your pregnancy, your unborn baby is only the size of half a pea. Yet something so small can affect your body so profoundly. Beyond symptoms such as morning sickness and sleepiness, your body begins undergoing significant physical changes within a few weeks of conception.
Menstrual Cycle
A skipped period is one of the most noticeable signs of a new pregnancy, but for many women, menstruation doesn't go away entirely, especially in the beginning. Some women experience implantation bleeding six to 12 days after conception when the embryo implants in the uterine wall. This might coincide with when you would normally expect your period and might be accompanied by cramping, so you could mistake it for a very light period. Generally, when women continue to menstruate after conception, their periods change significantly and become much lighter and shorter. Your normal periods may change to mere spotting.
Breasts
Along with alterations in your menstrual cycle, your breasts will also undergo significant changes in the first weeks of your pregnancy, sometimes as soon as a week after conception. As your body steps up production of estrogen and progesterone, mammary tissue reacts and becomes tender. Your breasts might also feel larger and heavier as your fluid and blood levels increase in response to your pregnancy. Some women also notice a darkening of their areolas. This, too, can occur as early as the first week after conception, although it may not occur until your second trimester. Experts blame it on an increase in blood volume and hormones.
Waistline
Weight gain goes hand-in-hand with pregnancy, and some women experience it right away, before their babies really begin growing. The average weight gain during the first trimester is about 5 lbs., although some women who experience morning sickness won't gain any weight at all. Even so, you may notice the waistband of your jeans pinching a little because no matter how much you've actually gained and how tiny your baby may be, your uterus is the approximately the size of a plum. Add to that, your increased blood circulation and a little water retention, and bloating very early in your pregnancy is not uncommon.
Aches and Pains
Physiological changes to your body can create minor aches and pains very early in your pregnancy. For instance, increasing estrogen levels can prompt headaches because the hormone constricts blood vessels. Backaches are also common, and not only in late pregnancy.
