Body changes in the first trimester of pregnancy

A woman's body goes under significant changes during pregnancy due to hormonal changes and the growth of the fetus.  These changes can cause concern if it is your first pregnancy.  This post will discuss normal changes in the first trimester of pregnancy.
A woman's threshold signal for thirst is altered causing a woman to drink more often which in turn causes a woman to need to urinate more often.  The change in thirst occurs to increase a woman's total volume of water in her body.  This increase allows a woman to increase her blood volume as well as contribute to the fluid content in the placenta and the amniotic fluid. 
A woman's appetite will increase during the first trimester in general, depending on how nauseated they feel.  A recommended amount of increased calories per day is 300 calories per day throughout the pregnancy.
Nausea and vomiting affect approximately 70 % of pregnancies.  It usually begins during the 4-8th week of pregnancy and usually stops by the 14-16th week.  Eating small meals frequently, ginger supplements, vitamin B6 or accupuncture wrist bands may be helpful.  There are also anti-nausea medication for women with more severe symptoms.
Constipation or diarrhea are also common in the first trimester which likely due to changes in the motility of the small intestines and large intestines. 
Breast changes associated with early pregnancy include tenderness and tingling sensations.  This occurs beginning the 4th week throught the 8th week.  The breasts continue to enlarge throughout pregnancy to prepare for lactation.  The nipples and the areola also enlarge.
Skin changes also occur during pregnancy.  Women may notice increaed acne which is due to the changes in hormones.  A woman may also noticed increased pigmentation (or darkening of the skin) during pregnancy.  This will usually resolve after delivery but may persist for some women.
A woman will also notice fatigue during pregnancy, especially the first trimester.  This usually improves during the second trimester but may redevelop during the third trimester.
Changes or symptoms that may occur during the first trimester that should prompt contact with your physician include vaginal bleeding, cramping, or severe nausea with an inability to maintain food intake.
I try to encourage my patients to hang in there through the first trimester.  Most patients will feel much better during the second trimester!