Genetics is proud to present "Week-by-Week:
Your Baby's Development." Please use this
utility to follow your baby's development throughout the weeks.
Week-by-Week: Your Baby's Development:
TRIMESTER 1 :::
Week 1 and 2:
Pregnancy is a 40 week adventure! This journey begins on
the first day of your last menstrual period (LMP). The menstrual
cycle [wiki link] is driven by changes in hormone levels.
During the first stage the lining of the uterus is shed. This
is experienced as flow from the vagina, often lasting 1-4
days. During the next 5-13 days the uterine lining begins
to build up again and the next egg/follicle starts to mature
in preparation for ovulation. At day 14, ovulation occurs.
One or more eggs are released into the fallopian tubes. At
day 15-28 the uterus prepares for possible implantation. If
implantation does not occur within approximately two weeks
the uterine lining again begins to shed.
At the end of week two, ovulation occurs. Sperm can survive
in cervical fluid as long as 5 days, so if sperm are already
present fertilization may occur soon after ovulation!
So the first two weeks are a bonus towards your 40 weeks
since you have not yet ovulated!
The sperm and egg meet forming a zygote! Congratulations
on your conception! The gender is determined at fertilization
and depends entirely on the sperm which carries either an
X or Y chromosome. If an X sperm joins the egg (always X),
then the gender of the zygote is female, and if a Y sperm
joins the egg, the zygote is male. After just 24 hours the
newly formed zygote consists of a cluster of cells and will
commence a one or two week journey through the fallopian tubes
to the uterus.
Your future child is smaller than a tip of a pen!
You may not yet know whether or not you or pregnant but if
you are planning a pregnancy consider researching prenatal
vitamins which are taken during pregnancy.
Once the zygote arrives in the uterus it will implant into
the uterine wall. Some women may feel some cramping or experience
light spotting at this time.
Women may experience breast tenderness and their blood volume
will increase. This extra blood requires your kidneys to work
overtime and is thought to contribute to the extra bathroom
trips many women experience. Women often feel fatigued since
the heart is also working harder to pump the extra blood.
Hormonal effects may also cause fatigue.
The cluster of cells begins to arrange itself into three
layers during the next two weeks. The outer layer will form
the skin, hair, eye lenses, tooth enamel, and salivary glands.
The middle layer will form the blood and vascular system,
muscle tissue, kidneys, and ureter. The inner layer will form
the trachea, bladder, urethra, prostate, ear canal, liver,
Based on pregnancy symptoms some women may take an at home
pregnancy test this week and discover the exciting and somewhat
scary news! Congratulations! Begin looking for a doctor whom
you feel comfortable with. You can choose a family practitioner
or an OB/GYN (obstetrics/gynecology) doctor.
Normally you would begin menstrual flow at the beginning
of this week so this is the time that many women may use at
home pregnancy tests when they realize their period is “late.”
Pregnancy tests check for human chorionic gonatropin (hCG)
levels and claim to be quite accurate on the first day of
a missed period. hCG causes an increase in estrogen and progesterone
which triggers many of the early pregnancy symptoms that women
Make an appointment with a doctor to confirm the at-home
pregnancy test results with a blood test.
Morning sickness and nausea are common during the first trimester.
Acupressure bracelets or certain foods (candied ginger, saltines,
graham crackers, cheese, or nuts) may help depending on your
Women will continue to experience breast and abdomen tenderness.
Fatigue will continue as your body adjusts to the hormonal
influences and organs work harder. Nausea often continues
for the first trimester. There is a lot going on inside of
your body and it is amazing the rapid development that occurs
from what started with a small cluster of cells.
The neural tube begins to form. This will develop into the
nervous system containing the brain, spinal cord, hair and
skin. The heart and primitive circulatory system form.
Hopefully you have found some prenatal vitamins by this time.
Also remember to stay hydrated! Prenatal vitamins are important,
and mainly contain increased folic acid and calcium compared
to normal multi vitamins. Increased folic acid intake greatly
reduces the risk of birth defects.
Blood begins to pump. Already there is a heartbeat! The embryo
is in the shape of the letter C. In the middle area of the
C the umbilical cord and organs develop. The beginnings of
arm and leg buds also appear. The embryo is 1.5-3 mm from
head to rump!
Make an appointment with your doctor to confirm the exciting
news if you have not already done so.
Women will continue to experience breast and abdomen tenderness.
Due to the increase in blood volume, your kidneys must work
harder to filter it all and you will continue to make those
extra bathroom trips! Fatigue will continue as your organs
work harder and your body adjusts to hormonal fluctuations.
Some women also notice an increase in saliva and/or swollen/bleeding
The embryo begins to take a more familiar shape as arm and
leg buds begin to lengthen. Eye spots appear which are indicative
of eye lens development. Nostril holes develop. Intestines
and pancreas begin to form. Brain development progresses and
the heart continues beating.
Fatigue and nausea remain, as do tenderness in breasts and
abdomen. Women often experience water retention and increased
At your first doctor appointment you will receive a full
physical with blood and urine testing. In some cases an ultrasound
Your future child has already tripled in size and is about
the size of a pea now!
During week 7 the face begins to take shape with ear holes,
some pigmentation in the eyes, and tiny nostrils. Teeth are
beginning to develop. Fingers and toes are forming as the
limbs lengthen but there are no individual digits yet. The
beginnings of elbows can be spotted. The digestive system
(intestines) and stomach start to form. The circulatory system
becomes more complex, the lungs begin to form, and the brain
continues to develop.
Your baby is the size of a pencil eraser!
During this week you will continue to experience fatigue.
Morning sickness does not just occur in the morning but any
time of day. Eating well can help you get through the day.
You may also be experiencing cravings and aversions to certain
foods and smells.
If you haven’t already experienced pregnancy symptoms
you may start this week with fatigue, nausea, tenderness of
abdomen and breasts. Breasts will increase in size during
this time as well. Remember to stay away from alcohol during
your pregnancy. Others around you may notice your pregnancy
glow. As blood flow increases your cheeks and face may glow.
Some women can feel their enlarged uterus (about the size
of a softball) when they press on their abdomens.
The baby’s cartilage and bone are forming. Fingers
and toes are webbed. Eyelids are forming, the nose is beginning
to protrude, upper lip is taking shape, and the tongue is
beginning to form. The intestines are moving into place.
Your baby’s heart beat is beating very quickly at about
150 beats per minute! Your child is 0.61 inches (1.6 cm) long
and weighs 0.04 ounces (1 gram).
Your face may break out thanks to the raging hormones. Fatigue
remains normal so make sure you can get the time to relax
and sleep extra. Limit strenuous exercise. Breast size may
increase as much as an entire cup size. Some women experience
increased vein size or stretch marks and itching. Some women
also experience leaking. The breasts prepare for breastfeeding
at the beginning of a pregnancy. Do some reading to prepare
yourself but do not become overwhelmed and remember to stay
The baby is beginning to move more although you can’t
feel it yet. Their joints are developing. Fingers are beginning
to develop fingerprints and can even curve around objects.
Your baby is 0.9 inches (2.3 cm) long about the size of a
quarter, and weighs 0.07 ounces (2 grams)!
To counteract your pregnancy symptoms make sure you get plenty
of rest, drink extra water, and get some gentle exercise.
You could join a prenatal class at this time. You may be starting
to show signs of your pregnancy.
If you haven’t seen your doctor yet, schedule that
first visit! Your doctor will do a thorough physical and then
expect to see you for shorter appointments once a month until
week 32 when you will go in every two weeks and then every
week after week 36.
The baby is now called a “fetus” since critical
development is achieved. Now your baby can primarily focus
on growing bigger. The baby has a large head and their irises
are beginning to form. The placenta is beginning to function.
The baby is now 1.22 inches (3.1 cm) long and weighs 0.14
ounces (4 grams).
Did you know you can take the Pink or Blue test NOW to determine
the gender of your baby?! You have only just found out you
are pregnant and may be experiencing some pregnancy symptoms.
Share the exciting news with your family (maybe now they’ll
understand your nausea and fatigue!), begin forming that close
bond with your new little baby boy or girl, and start thinking
about names earlier!
Pregnancy symptoms continue but may taper off beginning next
week! Consider beginning Kegels and other pelvic floor exercises.
You may begin to start noticing weight gain. Normal weight
gain during a pregnancy may be 25-35 pounds, or 40-45 pounds
for multiple births. You do not need to double your calorie
intake. Increasing it by 1/6th is about all that is necessary.
Remember to eat healthy and include plenty of protein, folic
acid, calcium and iron in your diet!
At this point your baby’s fingers and toes are separating
and hair and nails are beginning to grow. The genitals are
beginning to develop and the organs are beginning to function.
Amniotic fluid is beginning to accumulate. The baby’s
intestinal wall muscles practice contractions.
Your baby is now 1.61 inches (4.1 cm) long and weighs 0.25
ounces (7 grams).
Pregnant women may have more vivid dreams. Frequent bathroom
trips continue. Think about when to decide to tell your boss
that you are pregnant. Many women choose to wait until the
Your child’s vocal cords are developing this week.
Their eyes are moving closer together, ears are shifting into
position. The intestines move further into the body and the
liver begins to function. Insulin production begins. Development
continues in the nervous system but the brain is fully formed.
The thyroid gland begins functioning as do some other organs.
For some women, nuchal fold tests are typically done between
week 11 and 14 to check for down syndromes by ultrasound.
You also have the option to do amniocentesis or chorionic
villus sampling (CVS) at this time.
Your baby is now 2.13 inches (5.4 cm) long and weighs 0.49
ounces (14 grams).
See more information:
More Information About the
Consumer Genetics Products: