First Trimester

First Trimester
During the first trimester of pregnancy, you are just learning you are pregnant and coming to terms with both your fears and your hopes for the future. You may have been surprised to find out you were pregnant, and you or your partner may have some ambivalent feelings about the pregnancy. You may also begin to have fantasies and dreams about your child.

Many couples find they are less sexually active in the first trimester. As a result of their fluctuating hormones, fatigue and nausea, some, though not all, women find they are less interested in sex.

During these first three months, you will likely also notice the changes that are happening in your body. Most women will experience some of these physical changes during the first trimester:

missed menstrual periods
breast tenderness
nausea and vomiting, also known as “morning sickness”
urinary frequency
fatigue
increased basal temperature
weight gain
To learn more about how the discomforts you may experience, such as nausea and vomiting, can be treated, click here.

During the first trimester, the embryo, which began as a tiny cluster of cells, becomes a fetus and develops all of the major organ systems. Here is what is happening:

First Month (1-4 weeks)
embryo implants (attaches) to the wall of the uterus and develops rapidly
heartbeat begins on the 25th day
arm buds appear on the 26th day
leg buds appear on the 28th day
digestive system starts to develop
The embryo is 1/5th of an inch long.
Second Month (5-8 weeks)
the face is forming
ears covered by thin membrane, continue developing
spine begins to form
brain, liver, kidneys, bloodstream and digestive system are developing
arms and legs develop
By the end of the second month, the embryo has become a fetus. It is about 1 and 1/8th inches long and weighs 1/30th of an ounce.
Third Month (9-12 weeks)
the fetus' eyelids are fused
facial features are present, the nose and outer ears form
nail beds established
movement, such as head turning or sucking, begins
teeth buds form
all internal organs form
swallows amniotic fluid
The fetus is about three inches long and weighs one ounce. The placenta is fully developed and also weighs about an ounce. One to three ounces of amniotic fluid are present. By two months, a rudimentary umbilical cord has begun to circulate blood and nourishment to the fetus. At 12 weeks, the uterus is just above the pubic bone.