Encyclopedia of Health and Medicine

322 The Reproductive System
the most concentrated) or not properly timing the
duration of the test. Most health-care providers
will do a pregnancy BLOOD test at the first prenatal
visit to confirm the pregnancy. Pregnancy tests,
urine or blood, measure the presence of human
chorionic gonadotropin (hCG) or beta hCG.
Early signs of pregnancy a woman may detect
include
• tender, swollen breasts
• unexplained nausea and vomiting
• aversions to or cravings for certain foods,
including smells and sights of them
• profound tiredness
• sensation of lower abdominal bloating
• increased URINATION
• lightheadedness or dizziness
The health-care provider’s examination also
detects signs of pregnancy, including changes in
the texture (by internal palpation) and appearance
of the CERVIX and an enlarged, softened uterus. As
pregnancy advances the uterus rises out of the
pelvis and into the abdomen (beginning around
12 weeks). As part of the diagnostic process the
provider uses terminology to identify how many
pregnancies and how many deliveries the woman
has had previous to the current pregnancy, designating
them with the Latin words gravida and
para. A woman who has been pregnant twice and
delivered twice is a gravida 2 para 2, for example,
and a woman who is pregnant for the first time is
a primigravida nullipara or gravida 1 para 0.
Key Changes During Pregnancy
The woman’s body undergoes profound changes
during the course of pregnancy. Hundreds of hormones
unique to pregnancy initiate and facilitate
these changes, the most obvious of which are
enlarged breasts and a steadily expanding belly.
This biochemical flood is also responsible for the
emotional swings that characterize early pregnancy.
Nearly every body system modifies its
functions in some fashion to support the pregnancy
and the developing FETUS.
Uterus and abdomen The woman’s uterus,
pelvis, and abdominal structures flex and expand
to accommodate the fetus as it develops and
grows. The uterus, for example, can stretch up to
10 times its normal size during pregnancy. The
numerous hormones unique to pregnancy act on
connective tissue throughout the woman’s body
to soften ligaments and muscles, providing the pliability
necessary to allow this expansion. This softening
also accounts for the MUSCLE and JOINT aches,
especially in the hips and knees, common in the
last months of pregnancy.
The endometrium (lining of the uterus)
remains spongy and vascular to support the PLA-
CENTA. A plug of mucus collects in the cervix, helping
block BACTERIA from entering the uterus. The
tissues of the VAGINA and VULVA engorge with
blood, softening in preparation for childbirth. As
the pregnancy approaches term, the cervix softens
and thins (effaces). With the contractions of labor
the cervix dilates and the vagina expands to allow
passage of the fetus.
Breasts Changes in the breasts, notably tenderness
and swelling, are often the earliest indications
of pregnancy as the breasts respond to the hormones.
As pregnancy progresses a woman’s
breasts greatly enlarge and change in preparation
for BREASTFEEDING (lactation) after birth. The mammary
glands and ducts (milk glands and ducts)
swell and around the seventh month begin producing
colostrum, a fatty premilk that conveys
important NUTRIENTS and antibodies for basic
immunity to the infant.
Cardiovascular A woman’s blood volume and
cardiac output progressively increase as pregnancy
advances. The heart enlarges somewhat, HEART
RATE goes up, and blood pressure rises. In very
early pregnancy the blood vessels dilate in anticipation
of the increased blood volume, sometimes
resulting in episodes of lightheadedness or dizziness.
Some women also get vascular headaches in
response to the changes taking place within the
muscular walls of the arteries.
Gastrointestinal One of pregnancy’s early hallmarks
is MORNING SICKNESS, nausea and vomiting
doctors believe results from the hormones that
surge into the woman’s blood circulation when
the blastocyst implants. These same hormones are
responsible for softening connective tissue and
have similar actions on the muscular tissues of the
gastrointestinal system, sometimes slowing peristalsis
(movement of the intestines) enough to