The First Trimester
The first prenatal visit
The first prenatal visit is the
most thorough. A healthcare provider asks the mother-to-be about her health history
does a physical exam. Certain tests and procedures are also done to check the initial
health of the mother and her unborn baby. The first prenatal visit may include:
Personal health history. This may cover:
Past and current health
conditions, like diabetes, high blood pressure (hypertension), anemia, and
(prescription and over-the-counter)
Maternal and paternal family health history. The
healthcare provider will ask about illnesses such as diabetes or intellectual or
developmental disabilities. He or she will also ask about genetic disorders, like
sickle-cell disease or Tay-Sachs disease.
Personal gynecological and obstetrical history. The
healthcare provider will want to know about past pregnancies (stillbirths,
miscarriage, deliveries, terminations) and menstrual history (length and duration
of menstrual periods).
Education. The healthcare provider will talk with the
pregnant woman about the importance of eating a healthy diet, exercising
regularly, and not using alcohol, illegal drugs, and tobacco. He or she will also
cover any concerns about domestic violence.
Pelvic exam. This exam may be done for 1 or all these
To note the size and
position of the uterus
To determine the age of
To check the pelvic
bone size and structure
To perform a Pap test
(also called Pap smear) to find the presence of abnormal cells
Lab tests. These may include:
Urine tests. These are done to screen for
bacteria, sugar, and protein.
Blood tests. These are done to determine blood
type. All pregnant women are tested for the Rh factor during the early weeks
of pregnancy. A mother and fetus may have incompatible blood types. The most
common is Rh incompatibility. Rh incompatibility happens when the mother’s
blood is Rh-negative and the father’s blood is Rh-positive and the fetus’
blood is Rh-positive. The mother may make antibodies against the Rh-positive
fetus, which may lead to anemia in the fetus. Incompatibility problems are
closely watched. Treatment is available to prevent the formation of Rh
antibodies during pregnancy.
Blood screening tests. These are done to find
diseases, like rubella. This infectious disease is also called German measles.
Genetic tests. These are done to find inherited
diseases, like sickle-cell anemia and Tay-Sachs disease.
Screening tests. These are done to find infectious
diseases, like sexually transmitted infections (STIs).
The first prenatal visit is also a
good time for the mother-to-be to ask any questions or talk about any pregnancy
What to expect during the first
A healthy first trimester is
crucial to the normal development of the fetus. The mother-to-be may not be showing
on the outside. But inside her body, all the major body organs and systems of the
As the embryo implants itself into
the uterine wall, several developments take place:
Amniotic sac. A sac filled with amniotic fluid
surrounds the fetus throughout the pregnancy. The amniotic fluid is liquid made by
the fetus and the amnion (the membrane that covers the fetal side of the placenta)
that protects the fetus from injury. It also helps to regulate the temperature of
Placenta. The placenta is an organ shaped like a flat
cake that only grows during pregnancy. It attaches to the uterine wall with tiny
projections called villi. Fetal blood vessels grow from the umbilical cord into
these villi, exchanging nourishment and waste products with the mother’s blood.
The fetal blood vessels are separated from the mother’s blood supply by a thin
Umbilical cord. The umbilical cord is a rope-like cord
connecting the fetus to the placenta. The umbilical cord contains 2 arteries and a
vein. These carry oxygen and nutrients to the fetus and waste products away from
It is during this first trimester
that the fetus is most prone to damage from substances like alcohol, illegal drugs,
certain medicines, and illnesses, such as rubella.
During the first trimester, both
the mother’s body and the fetus are changing rapidly.
Fetal development during the first
The most dramatic changes and
development happen during the first trimester. During the first 8 weeks, a fetus is
called an embryo. The embryo develops rapidly. By the end of the first trimester,
becomes a fetus that is fully formed. The fetus weighs about 1/2 to 1 ounce and
measures, on average, 3 to 4 inches in length.
First trimester growth and development
Just as each child grows and
matures at different rates and at different times, so does that same child as it begins
its life in the womb. The chart below provides benchmarks for most normal pregnancies.
But each fetus develops differently.
|By the end of 4 weeks||
|By the end of 8 weeks||
|From embryo to fetus||
After 8 weeks, the
Although the fetus
|During weeks 9 to 12||
The fetus is most
Even though the
Changes in the mother’s body
During pregnancy, many changes are
also happening in the body of the mother-to-be. Women experience these changes
differently. Some symptoms of pregnancy continue for several weeks or months. Others
only experienced for a short time. Some women have many symptoms. Other women have
a few or none at all. Here is a list of changes and symptoms that may happen during
The mammary glands enlarge,
causing the breasts to swell and become tender in preparation for breastfeeding.
This is due to an increased amount of the hormones estrogen and progesterone. A
supportive bra should be worn.
A woman’s areolas (the
pigmented areas around each breast’s nipple) will enlarge and darken. They may
become covered with small, white bumps. These are called Montgomery tubercles
(enlarged sweat glands).
Veins become more noticeable
on the surface of the breasts.
The uterus is growing and
begins to press on the woman’s bladder. She may need to urinate more often.
Partly due to surges in
hormones, a pregnant woman may have mood swings much like premenstrual syndrome
(PMS). Women with PMS may have mood swings, irritability, and other physical
symptoms that happen shortly before each menstrual period.
Increased levels of hormones
to sustain the pregnancy may cause “morning sickness.” This is feelings of nausea
and sometimes vomiting. Morning sickness does not necessarily happen just in the
morning. And it rarely interferes with proper nutrition for the mother and her
Constipation may happen as
the growing uterus presses on the rectum and intestines.
The muscular contractions in
the intestines, which help to move food through the digestive tract, are slowed
due to high levels of progesterone. This may, in turn, cause heartburn,
indigestion, constipation, and gas.
Clothes may feel tighter
around the breasts and waist as the size of the stomach increases for the growing
A woman may be extremely
tired due to the physical and emotional demands of pregnancy.
Cardiac volume increases
by about 40% to 50% from the start to the end of the pregnancy. It causes an
increased cardiac output. An increased cardiac output may cause an increased pulse
rate during pregnancy. The increase in blood volume is needed for extra blood flow
to the uterus.