Pregnancy and Birth

Pregnancy and Birth
Fertilization / Conception
• When the males sperm enters the females egg
• 1 sperm / 1 egg
• Within seconds of fertilization, the surface of
the egg changes so that no more sperm may
enter the egg
• The united egg and sperm
• Within 36 hours, while the zygote is in the
fallopian tube, it begins to divide
Cell Division
The original cell divides to make 2 cells
8  16, etc.
From the 2 cell stage until about 9 weeks after
fertilization, the growing structure is called an
The Blastocyst
• 5 days after fertilization, the embryo reaches
the uterus
• Floats free
• 50 to 100 cells
• Blastocyst – sphere of
cells surrounding a
hollow center
• Once the blastocyst forms, it implants itself in
the uterus  implantation
Amniotic Sac
• After implantation, a fluid-filled bag of thin
tissue called the amniotic sac develops around
the embryo
• It grows as the
embryo grows
• Embryo floats in
amniotic fluid
• The attachment that holds the embryo to the
wall of the uterus
• Here, oxygen and nutrients move from the
mothers blood into the embryo
• Dangerous substances can pass from mother
to embryo, too
– Alcohol, drugs, chemicals
Umbilical Cord
25 days
Ropelike structure
Connects embryo to placenta
The embryo’s lifeline
Carry nutrients and oxygen from the placenta
to the embryo
• Carry wastes from the embryo to the placenta
The Growing Embryo
• During the first 2 months:
– Major body systems and organs form
• Heart, Blood vessels, Kidneys, Endocrine glands
• At the end of 2 months:
– Embryo is an inch long
– Recognizable external features
• Eyes, ears, arms, legs
– Head makes up 50% of embryo
The Fetus
• From the 3rd month until birth, the developing
human is called a fetus
• 3rd to 6th months – begins to kick
– Skeleton and muscles are developing
• Nervous system matures
– Sense organs begin functioning
• Fetus becomes sensitive to light and sound
• Alternates periods of activity with sleep
The Fetus
• 7th to 9th months
– Body size increases; more proportionate
– Body fat accumulates
– Eyelids open and close
• End of 9th month
– Fetus is ready to be born
Worksheet Word Bank
• Blastocyst
• Fertilization
• Early Cell Division
• Blastocyst & Implantation
• Late Cell Division
• Cervix
• Vagina
• Amniotic Sac
• Developing Placenta
• Amniotic Fluid
• Uterine Wall
• Umbilical Cord
Staying Healthy During Pregnancy
• Proper nutrition
– “eating for two”
• Exercise
– Better meet the energy needs of carrying a baby
• Avoiding alcohol and other drugs
– Harm, kill, decrease chance to live, lifelong problems
• Avoiding environmental hazards
– X-rays, lead, mercury (fish), cat litter (parasites)
Prenatal Care
• Medical care during pregnancy
• Obstetrician – doctor specialized in pregnancy
and childbirth
• The chances of having a healthy baby greatly
increases with regular doctor checkups
throughout pregnancy
3 Trimesters
• Pregnancy is divided into 3 periods of time
• Each is about 3 months long
• 1st trimester  0-3 months
• 2nd trimester  3-6 months
• 3rd trimester  6-9 months
Monitoring Tools
• Ultrasound
– High-frequency sound waves that produce an
image of the fetus
• Chorionic Villus Sampling (CVS)
– At 8 weeks, dr. removes part of the placenta to
check for abnormalities/disease
• Amniocentesis
– 14-16 weeks, inserting a needle in the abdomen
and uterus to remove amniotic fluid to test for
• Ectopic pregnancy
– Blastocyst implants in the fallopian tube, not the
• Miscarriage
– Death of embryo or fetus in first 20 weeks
• Preeclampsia
– High BP, swelling of wrists & ankles, high levels of
protein in urine  prevents fetus from getting O2
• Gestational diabetes
– Developing diabetes while pregnant
The Birth Process
1. Labor
2. Delivery of the baby
3. Delivery of the afterbirth
• Work performed by the mother’s body to
push the fetus out
• 2 to 24 hours or longer
• Uterus contracts, causing the cervix to
increase in width, or dilate
• Amniotic sac will break
• Cervix becomes softer and wider too allow the
fetus to pass through
Delivery of Baby
Actual birth, or delivery of baby
Lasts 30 minutes to more than 2 hours
Baby usually exits head first through vagina
Once the baby is out:
– Dr. clamps and cuts the umbilical cord
– Baby’s nose & mouth are suctioned to remove
mucus and make it easier to breath
– Eye drops are given to prevent infection
– Injection of vitamin K to prevent excess bleeding
from umbilical cord
Delivery of Afterbirth
• Though the baby is born, the birth process is
not complete
• Uterus contractions push out the placenta
• 15 to 30 minutes
Complications at Birth
Surgical delivery
Premature birth
Low birth weight
Birth of more than one baby
Surgical Delivery
• Sometimes delivery through the cervix and
vagina is not possible due to the position of
the fetus or the narrowness of the mothers
• Illness or other conditions that make vaginal
delivery dangerous for mother and/or baby
Cesarean Section
• Surgical method of birth
• Doctor makes an incision in the lower
abdomen into the uterus
• Then removes the fetus and placenta
Premature Birth
Baby is born before it is fully developed
Before the 37th week of pregnancy
Earlier birth  more problems
Lungs are usually not developed
Receive care in an incubator
Low Birth Weight
• Less than 5.5 pounds
• May also be premature
• May be full-term, just didn’t grow enough
before birth
• Increased risk of health problems as a
newborn, chronic lifelong problems, death
Multiple Births
• The delivery of more than one baby
– Twins
– Triplets
– Quadruplets
• Carry greater risk to mother and babies
Identical Twins
• Develop from single fertilized egg
• Embryo divides into 2 identical embryos
• Because they divide from identical embryos,
they have the same inherited traits and are
the same sex
Fraternal Twins
• Sometimes 2 eggs are released from the ovary
and fertilized by 2 sperm
• Fraternal twins are no more
alike than any other siblings
• May or may not be the
same sex
Triplets or More
• Less common than twins
• Number of cases has dramatically increased in
the last 25 years

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