Having a baby and feeling a new life developing inside is an amazing,
life-changing experience for pregnant women, even though they may not
always feel their best along the way.
Pregnancy can be different from woman to woman, and even for the same
mother from one pregnancy to the next. Some pregnancy symptoms last for
several weeks or months, while other discomforts are temporary or don't
affect every
woman who is expecting.
"Pregnancy is a long, 10-month journey," said Dr. Draion Burch, an
obstetrician and gynecologist at Magee-Womens Hospital at the University
of Pittsburgh Medical Center.
A normal pregnancy usually lasts about 40 weeks, counting from the
first day of a woman's last menstrual period, which is typically about
two weeks before conception occurs.
The stages of pregnancy are typically described in three-month periods
known as trimesters. Each trimester lasts between 12 and 13 weeks.
During each trimester, distinct changes take place in a pregnant
woman's body as well as in the development of the fetus, and they will
be described in greater detail below.
Conception and implantation
About two weeks after a woman has her period, she ovulates and her
ovaries release one mature egg. The egg can be fertilized for 12 to 24
hours after it's released as it travels down the fallopian tube toward
the uterus.
If an egg meets up with a sperm cell that has made its way into the
fallopian tube, it combines into one cell, a process that's known as
fertilization or conception.
At fertilization, the sex of the fetus is already determined, depending
on whether the egg receives an X or Y chromosome from a sperm cell. If
the egg receives an X chromosome, the baby will be a girl; a Y
chromosome means the baby will be a boy.
According to the Cleveland Clinic, it takes about three to four days
for the fertilized egg (or embryo) to move to the lining of the uterus,
where it attaches or implants to the uterine wall.
Once the embryo is implanted, the cells start to grow eventually
becoming the fetus and the placenta, which is tissue that can transport
oxygen, nutrients and hormones from the mother's blood to the developing
fetus throughout pregnancy.
First trimester (weeks 1-12) changes in the mother's body
A woman will experience a lot of symptoms during her first trimester
as she adjusts to the hormonal changes of pregnancy, which affect
nearly every organ in her body. The pregnancy may not be showing much on
the outside of her body, but inside many changes are taking place.
Human chorionic gonadotrophin (hCG) is a hormone that will be present
in a woman's blood from the time conception occurs. Produced by cells
that form the placenta, hCG can be detected in a woman's urine about a
week after a missed period and is responsible for a positive result on a home pregnancy test.
Rising levels of pregnancy hormones may also bring on the waves of nausea and vomiting known as morning sickness that
a woman typically feels during her first few months of pregnancy. Some
smells may be more bothersome now and provoke queasiness.
She will also feel more tired than usual, a symptom that's linked with
rising levels of the hormone progesterone, which increases sleepiness. A
woman's uterus is growing and begins to press on the bladder, causing
her to urinate more frequently.
Early in pregnancy, a woman's breasts will feel more tender and
swollen, another side effect of rising pregnancy hormone levels. A
woman's areolas, the skin around each of her nipples, will darken and
enlarge.
Her digestive system may slow down to increase the absorption of nutrients, but this might also lead to such common complaints as heartburn, constipation, bloating and gas, according to womenshealth.gov.
In addition, a pregnant woman's heart will be working even harder,
increasing the volume of blood it pumps to supply the uterus with the
additional blood it needs to supply the fetus and elevating her pulse
rate.
As more blood circulates to a woman's face, it will give her skin a rosier complexion, described as a "pregnancy glow."
Besides the physical changes in a woman's body, she will also
experience emotional highs and lows in the early months of her pregnancy
and throughout it. These emotions may range from weepiness, mood swings
and forgetfulness to fear, anxiety and excitement.
First trimester development of embryo/fetus
A developing baby is called an embryo from the moment conception takes place until the eighth week of pregnancy.
During the first month of pregnancy the
heart and lungs begin to develop, and the arms, legs, brain, spinal
cord and nerves begin to form, according to the American College of
Obstetricians and Gynecologists (ACOG).
The embryo will be about the size of a pea around one month into a
pregnancy, Burch said. Around the second month of pregnancy, the embryo
has grown to the size of a kidney bean, he explained. In addition, the
ankles, wrists, fingers and eyelids form, bones appear, and the genitals
and inner ear begin to develop.
After the eighth week of pregnancy and until birth occurs, a developing baby is called a fetus.
By the end of the second month, eight to 10 of the fetus' main organs
will have formed, Burch said, which is why he stresses to pregnant women
that it's extremely important to not take harmful medications, such as
illegal drugs during that time. The first trimester is also the period
when most miscarriages and birth defects occur.
During the third month of pregnancy, bones and muscles begin to grow,
buds for future teeth appear, and fingers and toes grow. The intestines
begin to form and the skin is almost transparent.
Second trimester (weeks 13-27) changes in the mother's body
By the second trimester, some of the unpleasant effects of early
pregnancy may lessen or disappear as the body adjusts to its changing
hormone levels. Sleeping may get easier and energy levels may increase.
Nausea and vomiting usually gets better and goes away, Burch said. But
other symptoms may crop up as the fetus continues its growth and
development.
Women feel more pelvic pressure, Burch said, adding that the pelvis feels heavy like something is weighing it down.
A more visible baby bump appears as the uterus grows beyond a woman's pelvis, and the skin on her expanding belly may itch as its stretches, according to womenshealth.gov.
As the fetus is getting bigger and a woman is gaining more pregnancy
weight in the front of her body, she may also experience more back pain,
Burch said.
Somewhere between the 16th and 18th week of pregnancy a first-time
mother may feel the first fluttering movements of the fetus known as
quickening, Burch said. If a woman has had a baby before, she is likely
to feel the fetus kicking, squirming or turning even sooner because she
knows what to look for and expect, he explained.
The 20th week usually marks the halfway point of a woman's pregnancy.
Burch encourages his patients to take a "baby-moon" — a mini-vacation
or weekend getaway — during the second trimester, and he said the best
time to get away is around the 28th week of pregnancy. A woman is
generally feeling pretty good at this point, there's a lower risk of
miscarriage and premature labor, and some health professionals may
discourage airplane travel after the 36th week.
Second trimester development of the fetus
In the second trimester
, the fetus is growing a lot and will be between 3 and 5 inches long, Burch said. Somewhere between 18 and 22 weeks an ultrasound may reveal the sex of the baby, if parents want to know it in advance.
By the fourth month of pregnancy, eyebrows, eyelashes, fingernails and
the neck all form, and the skin has a wrinkled appearance. Some other
highlights this month include that the arms and legs can bend, the
kidneys start working and can produce urine, and the fetus can swallow
and hear, according to ACOG.
In the fifth month of pregnancy, the fetus is more active and a woman
may be able to feel its movements. The fetus also sleeps and wakes on
regular cycles. A fine hair (called lanugo) and a waxy coating (called
vernix) cover and protect the thin fetal skin.
By the sixth month of pregnancy, hair begins to grow, the eyes begin to
open and the brain is rapidly developing. Although the lungs are
completely formed, they don't yet function.
During the third trimester
,
as a woman's enlarged uterus pushes against her diaphragm, a major
muscle involved in breathing, she may feel short of breath because the
lungs have less room to expand, according to Johns Hopkins Medicine. Her
ankles, hands, feet and face may swell as she retains more fluids and
her blood circulation slows.
A mother-to-be will need to pee more frequently because more pressure
will be placed on her bladder. She may also have more backaches and more
pain in the hips and pelvis, as these joints relax in preparation for
delivery.
Her face may develop dark patches of skin, and stretch marks may appear
on a woman's belly, thighs, breasts and backside. She may also notice
varicose veins on her legs.
Her breasts may experience some leakage of colostrum, a yellow liquid, as they get ready for breastfeeding, according to womenshealth.gov.
False labor, known as Braxton-Hicks contractions
,
may begin to occur as a woman gets closer to her due date. A "nesting
instinct" may kick in as a woman and her partner baby-proof their home,
shop for baby items, prepare the nursery and eagerly await their new
arrival.
It will become harder to find a comfortable sleeping position during
the final weeks of pregnancy, so women may be extremely tired, Burch
said.
As delivery approaches, "some women love the experience of being
pregnant, while others may feel like they don't want to go through it
again," Burch said.
Third trimester development of the fetus
By the seventh month of pregnancy, the fetus kicks and stretches, and can even respond to light and sound, like music, Burch said. The eyes can open and close.
During the eighth month of pregnancy, the fetus gains weight very
quickly. Bones harden, but the skull remains soft and flexible to make
delivery easier. Different regions of the brain are forming, and the
fetus is able to hiccup, according to ACOG.
The ninth month is the home stretch of pregnancy and the fetus is
getting ready for birth by turning into a head-down position in a
woman's pelvis. The lungs are now fully mature to prepare for
functioning on their own. The fetus continues to gain weight rapidly.
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