Pregnancy and Prenatal Development

Adapted from an online publication by Sid T. Womack

  Stages of Prenatal Development

Germinal (Period of the Zygote) (first two weeks: conception until implantation)

Embryonic (Period of the Embryo) 3rd through 8th weeks

Fetal (Period of the Fetus) 9th week (development of first bone cells) until

birth

Important vocabulary:

Pregnancy is also separated into Trimesters

1st Trimester = months 1, 2 and 3 2nd Trimester = months 4, 5, and 6 3rd Trimester = months 7, 8, and 9

Conception

Conception: when a sperm cell penetrates and fertilizes an egg cell

Successful conception depends on ovaries releasing one healthy egg cell egg cell migrates most of the way down the

fallopian tube one sperm must penetrate the ovum to form a

zygote

Important vocabulary:

Sperm and Ovum

Infertility

About 15 percent of couples are unable to conceive or carry a pregnancy to term after one year

Causes of male infertility quantity or strength of sperm produced

Causes of female infertility structural abnormalities in the fallopian tubes or

uterus failure to ovulate and release mature eggs

Options for infertility: adoption, artificial insemination, In-vitro fertilization, ovum transfer, surrogate mother

Important vocabulary:

Signs of Pregnancy

Presumptive Signs Changes in a woman's body that may

be due to pregnancy or something elseAmenorrhea, Nausea, tiredness, frequent

urination, swollen/tender breasts, etc

Positive Signs Changes in a woman’s body definitely

caused by pregnancyBlood/urine test positive for HCG, fetal

presence detected through stethoscope, ultrasound or other means

Important vocabulary:

The Germinal Stage (first two weeks: conception until implantation)

1. The blastocyst (ball of cells) is differentiated into three layers:

• Known as a zygote• It will become the embryo AND nourishing/protecting tissues

2. The blastocyst moves down the fallopian tube into the uterus for implantation.

• Implantation: zygote attaching to the wall of the uterus• Only 1 in 4 zygote survives

3. The germinal stages ends with implantation.

• The fully implanted zygote is referred to as the embryo.

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Blastocyst at day six

Embryonic Stage (3rd through 8th weeks)

1. Growth in the embryonic and fetal stages follows these patterns:

cephalocaudal (head-to-tail) proximodistal (near-to-far)

Examples: The head, blood vessels, heart, and most vital organs

(near/inside) begin to develop before the arms, legs, hands, and feet (far/outside).

The brain (head) begins to develop before the legs and feet (tail)

Important vocabulary:

Early Embryonic Stage

Embryonic Stage• 2.The placenta

– an organ that connects and nourishes the embryo• 3.The umbilical cord

– connects the embryo to the placenta – contains three blood vessels

*1 carries nutrients to the embryo

*1 carries oxygen to the embryo *1 carries away waste products

• 4.The amniotic sac – surrounds and protects the embryo – filled with amniotic fluid

Important vocabulary:

Fetal Stage (9th week to birth)

The fetal stage begins with the development of the first bone cells.

• The embryo is now called the fetus.

Third month• the fetus is able to move its head, legs, and

feet• sperm and ova present

Fourth Month• mother may feel quickening, or fetal

movement

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Fetal Stage

THIRD TRIMESTER (MONTHS 7-9)Age of viability

• beginning of the seventh month (24 weeks)

• fetus may be able to survive outside the womb

**Rapid weight gain, brain and respiratory maturation **

Ninth month• fetus weighs an average of 7.5 pounds and is

almost 20 inches long• positioned for birth

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Fetus at 12 weeks

Monitoring Development Ultrasound

Sound waves used to produce a sonogram or a picture of the unborn baby

Used routinely to check size, gender and health

AFP (Alfa-fetoprotein) Mothers blood is tested to identify abnormal levels of AFP No risk known

CVS (Chorionic Villus Sampling) Tube inserted through vagina takes a sample of the

chorion Slight risk of infection and miscarriage

Amniocentesis Needle inserted through abdomen to take sample of

amniotic fluid Slight risk of miscarriage or premature birth

Fetus at 18 weeks

Negative Prenatal InfluencesHealth Hazards to Avoid

Only 20% of birth defects are strictly inherited (two defective recessive genes or one defective dominant gene)

Some caused by errors in chromosomes

*Many caused by environmental factors—drugs, disease, radiation, environmental pollutants

Teratogen is any substance or influence that can interfere with or damage a baby’s growth

Important vocabulary:

1. Maternal DiseasesRubella, or German measles

heart problems, deafness

Syphilis and gonorrhea Blindness, jaundice, anemia, pneumonia, skin

rash, early death Silver nitrate in the eyes for treatment

Genital herpes Disease of skin and mucous membranes,

blindness, permanent brain damage, seizures, and developmental delay

C-section recommended for delivery during outbreak

Maternal diseases

Cytomegalovirus (CMV) Brain, liver, and blood defectsFatal for embryo (exposure 3rd-8th week)

Toxoplasmosis Parasite from uncooked meat and cat feces

Low birth weight, enlarged liver and spleen, microcephaly, anemia, and calcifications in the brain

AIDS Possible death of child within two years if

transmitted

2. Teratogenic Medicinal Drugs

Thalidomide A sedative once prescribed to prevent morning

sickness Deformed eyes, ears, nose, heart, limbs

Diethylstilbestrol (DES) Used to prevent miscarriages

Causes damage to reproductive systems of offspring

Oral Contraceptives Heart defects

3. Teratogenic Non-medicinal drugs

Marijuana THC is stored in fatty tissues of body Placenta is not a barrier Babies are born with addiction

Heroin Severe withdrawal symptoms Newborns vomit, tremble, have fevers,

disturbed sleep, and abnormal cries

Alcohol

Fetal Alcohol Syndrome (FAS)Spectrum of disorders Central Nervous System

damage heart defectssmall head distortion of jointsabnormal facial featuresdifficulty with focus and

attention

Tobacco

Nicotine and carbon monoxide interfere with fetal oxygen supply

Smoking is associated with low birth weight spontaneous abortion higher infant mortality poor postnatal

adjustment

Paternal Influences

Fathers’ exposure to teratogens can also cause problems with prenatal development

Studies have found trace elements of residues in semen Radiation linked with genetic defects and spontaneous

abortion Lead linked with miscarriage, stillbirth and cancer Toxic smoke (including cigarettes) linked with heart

defects and cancer Drinking and drug use linked with low birth weight and

various defects

Prenatal Health Care

Adequate and early prenatal health care is critical to infant and maternal health.

Obstetriciandoctors specializing in care of pregnant

women

Certified Nurse Midwife (CNM)nurses trained in care of normal

pregnancies

Factors that Affect Baby’s Health

1. AGE–Women in their teens or over 35 have a

greater risk for complications, birth defects, and fetal/neonatal fatality

–Good prenatal care can offset risks

2. Maternal diet and nutrition

Poor nutrition • physical deformities • increased risk for prematurity and infant mortality• reduced number of brain cells (future mental

capacity)

Eating• 200 to 1000 extra calories per day• mainly carbohydrates and protein

Weight Gain• 3-5 pounds during the first three months• 1 pound a week throughout the rest of the pregnancy• 25-30lbs total

Supplements• A prenatal multivitamin is often recommended

Pregnancy Weight DistributionBaby 8 lbs.

Placenta 1 1/2 lbs

Amniotic Fluid 2 lbs.

Utreus 2 lbs

Breast 2 lbs.

Increase of Blood 4 lbs

Increase of Fluid 4 lbs.

Maternal Storage of fats,proteins & other nutrients 7 lbs.

3. Emotional State

Prolonged anxiety just before or during pregnancy increases the likelihood of medical complications, miscarriage, prolonged labor, low birth weight, and difficult babies.

4. Rh FactorProtein in red blood cells of some

people Rh+ father and Rh- mother

If baby inherits Rh+, antibodies produced by mother can harm baby

RH Immune Globulin vaccine blocks antibodies

5. EclampsiaHigh blood pressure occurring later in

pregnancy which inhibits mothers ability to process wastes

Can be fatal to mother and baby

Childbirth

CHILDBIRTH

At thirty-eight weeks in the womb, the baby is considered "full term," or ready for birth

Labor: the process by which the baby moves out of the uterus and through the vagina to be born

Delivery: the birth

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Signs of LaborRegular Contractions

Contraction: tightening and releasing of uterine muscles

• Time how long each cramping period lasts and the length of time in between each contraction.  Keep a record for an hour.  During true labor . . . 

– the contractions last about 50-80 seconds  – they occur at regular intervals  – they don't go away when you move

around During the last weeks of pregnancy, it is

common for the mother to experience false labor, or Braxton-Hicks contractions

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Signs of Labor: continued

Burst of Energy– Increased adrenaline

The Show– Mucus plug is dislodged form cervix– Labor within about 24 hours

Ruptured Waters– Amniotic sac breaks—slow leak or

rush of fluid– Risk of infection increases—no bathing

Fetal Presentation

The body part of the fetus closest to the mother's cervix three types of

presentation: Cephalic (normal):

• head firstBreech:

• feet, knees, or buttock first– 3 to 4% of deliveries

Transverse: • Shoulder, arm, or back first

– 1% of deliveries– Usually require c-section

Important vocabulary:

Stages of labor Stage 1: Dilation of Cervix

• Usually begins with relatively mild contractions, leading to stronger contractions

– Early labor: 0 to 3 centimeters dilated– Active labor: 3 to 10 centimeters dilated

• Dilation of the cervix to accommodate the baby's head (10 centimeters)

– Dilation: flattening and opening of the cervixImportant vocabulary:

Stage 1: Dilation of Cervix: continued

•Amniotic sac may break or be ruptured by the doctor

•Eight to twenty-four hours (average)

•Toward the end, a period of transition begins, and the baby's head begins to move through the birth canal

Stages of laborStage 2: Expulsion of

Baby From complete dilation of the

cervix to birthAbout ½ to 1½ hoursStrong urge to pushEpisiotomy possible

• an incision into the perineum (skin between the vagina and the anus)

• to prevent tearingBaby delivered

• Suction nose and mouth• Clamp and cut umbilical cord

Stages of labor

Stage 3: Expulsion of the Placenta The afterbirth is expelled

Continued irregular contractions dislodge the placenta from the uterine wall

Placenta and umbilical cord are expelled About 20 to 30 minutes

Cesarean SectionC-Section

surgical incision is made in the mother's abdomen and uterus to deliver the baby

Reasons for Cesarean Delivery Size of the baby

• If a baby is very large, it might not be able to pass safely through the mother's pelvis

Maternal medical conditions • Diabetes, high blood pressure, herpes infection or

other conditions Position of the placenta

• The placenta sometimes blocks the path of exit from the uterus

Multiple births• If more than one baby is being born

Reasons for Cesarean Delivery: continued

Failure of labor to progress• If labor stops before the baby is born and cannot

be started by medication

Health of the baby• If the baby shows signs of distress such as an

abnormal heart rate

Previous cesarean birth• The doctor may discuss with the mother that

having delivered one baby by cesarean might mean it would be best to have other babies delivered by cesarean

Types of Pain Relief Behavioral Techniques

breathing methods, relaxation techniques

Analgesia: relief of pain without total loss of sensation 

Systemic Analgesia provide pain relief over the entire body

without loss of consciousnessan injection into a muscle or veinmay cause drowsiness and may make it hard to

concentrateBecause these drugs can slow the baby's reflexes

and breathing at birth, they are usually avoided just before delivery. 

Types of Pain ReliefAnesthesia: relief of pain through loss of

sensation

Local Anesthesia Injection into the vagina or the area

surrounding it to ease pain during delivery Useful when the health care provider has to

make an episiotomy or repair it after birth

General Anesthesia Loss of consciousness Most often used for cesarean delivery or

other urgent situations

Types of Pain Relief: contSpinal Block

Injection in the lower back into the spinal fluid given only once relieve pain almost immediately pain relief lasts only 1-2 hours Best suited for pain relief during delivery (not

labor), particularly if forceps or vacuum extraction is needed

Pain relief method most often used for cesarean birth 

Epidural Block Local anesthesia that affects a much larger area Catheter inserted into the lower back, where the

nerves that receive sensations from the lower body meet the spinal cord

Medication injected into the catheter Numbs the lower half of the body to a varying

extent, based on the drug and dose used

Childbirth settings and methods

•Traditionally, childbirth was attended by a midwife and was seen as a natural process

•With modern technology, births have increasingly taken place in medical settings

•Decreased mortality rates, but birth was now seen as a medical event controlled by physicians

Hospital Births

Birthing rooms are becoming more popular in hospitals

LDRP’s — Labor, Delivery, Recovery and Postpartum all in one room

more comfortable for mothers and families

Non-hospital settings

Freestanding birth centers

non-hospital facilities that provide family centered maternity care

Lower rates of Caesarean sections

Home birthsBirthing at home with a

midwifeA choice for low risk

pregnancies

Prepared Child Birth

Using Behavioral techniques to enhance the birthing process and reduce pain naturally educational, physical, and emotional

preparation for the birth process and use of a coach

women who participate in birthing programs report positive effects

many believe a gentle birth has benefits for the child

Lamaze birth philosophy Birth is normal, natural, and healthy.

The experience of birth profoundly affects women and their families.

Women's inner wisdom guides them through birth.

Women's confidence and ability to give birth is either enhanced or diminished by the care provider and place of birth.

Women have the right to give birth free from routine medical intervention.

Birth can safely take place in birth centers and homes.

Childbirth education empowers women to make informed choices in health care, to assume responsibility for their health, and to trust their inner

wisdom.

Leboyer Birth philosophy

A childbirth method focused on comfort and safety of the baby during delivery

Assumes delivery is painful for both baby and mom

Low lights and noiseAfter birth, baby is placed on moms bodyUmbilical cord isn’t cut until baby starts

breathing on its ownBaby is put in warm water to move around

for awhile before being wrapped in blankets

Low-birth weight infants

Normal is around 7.5 pounds

Low-birth weight is 5.5 pounds or less

6 or 7 percent of all births in U.S.

At risk for developmental, neurological, and other health problems

Pre-term Babies

Formerly called premature

More than three weeks before due date

At risk for respiratory distress syndrome (RDS)

Neonatal Assessment

The APGAR test

developed in 1952 by the late pediatrician, Dr. Virginia Apgar used to quickly evaluate a newborn's condition after delivery

A score is given for each sign at one minute and five minutes

If there are problems, an additional score is given at 10 minutes

Scoring7-10 is considered normal4-7 might require some resuscitative measures3 and below requires immediate resuscitation

APGAR Scale

 Sign 0 Points1 Point

2 Points

A Activity (Muscle Tone)

Absent Arms and Legs Flexed Active Movement

P Pulse Absent Below 100 bpm Above 100 bpm

G Grimace (Reflex Irritability)

No Response GrimaceSneeze, cough, pulls

away

A Appearance (Skin Color)

Blue-gray, pale all over

Normal, except for extremities

Normal over entire body

R Respiration Absent Slow, irregular Good, crying

Neonatal Assessment The Brazelton Scale

Behavioral and reflex measurements used to assess a baby's capabilities across four developmental areas

Breathing

Motor Control

Response, or "state" regulation

Social Interaction

Measures 28 behavioral and 18 reflex items

Gives parents details about the baby's specific needs and styles of behavior

Breastfeeding

The first feeding after delivery

Immediately after delivery, baby should be placed on mom’s chest or abdomen, skin to skin

Baby’s first feeding can take place within 30 minutes to an hour after delivery

The protection against infection that human milk provides is important immediately after birth

Gives the baby nutrients to prevent a low blood sugar level

By the third or fourth day of breastfeeding, milk will change from colostrum to what looks more like skim milk

Breastfeeding

Breastfed children are less likely to have the following:

Ear infections Allergies Vomiting Diarrhea Pneumonia, wheezing, and

bronchiolitis Meningitis May help to protect

against Sudden Infant Death Syndrome (SIDS)

Breast milk is best because: It is easier for babies to digest It does not need to be prepared It costs nothing to make and is

always in supply It is good for the environment

since there are no bottles, cans, and boxes to put in the garbage

Breastfeeding also provides physical contact, warmth, and closeness, which help to create a special bond between a mother and her baby

Breastfeeding

Breastfeeding benefits moms: Burns more calories and helps you get back to your prepregnancy

weight more quickly.

Reduces the risk of ovarian cancer and, in premenopausal women, breast cancer.

Builds bone strength to protect against bone fractures in older age.

Delays the return of your menstrual period, which may help extend the time between pregnancies. Helps the uterus return to its regular size more quickly.

The longer you breastfeed, the greater the benefits will be to your baby and you, and the longer these benefits will last. Experts encourage women to breastfeed for as long as possible (1 year or even longer)