Anatomy: Fetus in Utero A thin-walled sac surrounds the fetus during pregnancy. The sac is filled with amniotic fluid, which protects the fetus from injury. Hormones During Pregnancy Many hormone levels are affected in the body during pregnancy, with several hormones playing major roles. Weight Gain During Pregnancy Average weight gain for women is between 25 and 35 pounds, although slight deviations from this may also be considered normal. Common Discomforts During Pregnancy Nausea and vomiting are common in the first trimester, as is fatigue. Other common discomforts are hemorrhoids and heartburn. Pregnancy and Posture Much back pain in pregnancy is related to the strain on your back from the weight of your growing baby. Using proper posture can help prevent and even relieve some of the pain. Managing Hemorrhoids and Varicose Veins in Pregnancy Hemorrhoids and varicose veins might seem to be two different, unrelated problems, but they are actually quite similar. And, they are a discomfort experienced by many women, especially in the third trimester of pregnancy. Pregnancy and Heartburn Chances are good that you’re one of more than three-fourths of pregnant women who experience the churning and burning of heartburn or acid indigestion. It typically hits somewhere in the second or third trimester, and it can be miserable.