PSYC 50Developmental Psychology

Chapter 4: PRENATAL DEVELOPMENT AND BIRTH

PRENATAL DEVELOPMENTThe Course of Prenatal Development

The course of prenatal development last approximately 266 days, beginning with fertilization and ending with birth.

Three periods of prenatal development:1. Germinal Period – takes place in the first two weeks after

conception. It includes the creation of the zygote, continued cell division, and the attachment of the zygote to the uterine wall.

Blastocyst – the inner mass of cells that develops during the germinal period. These cells later develop into the embryo.

Trophoblast – an outer layer of cells that develops in the germinal period. These cells will become part of the placenta.

Implantation – the attachment of the blastocyst to the uterine wall, takes place about 10 to 14 days after conception.

2. Embryonic Period – occurs from two to eight weeks after conception. During the embryonic period, the rate of cell differentiation intensifies, support systems for the cells form, and organs appear.

Placenta – a disk-shaped group of tissues in which small blood vessels from the mother and offspring intertwine but do not join.

Umbilical cord – contains two arteries and one vein; connects the baby to the placenta.

Amnion – the life-support system that is a bag or envelope containing a clear fluid in which the developing embryo floats.

Organogenesis – organ formation that takes place during the first two months of prenatal development.

After the blastocyst attaches to the uterine wall, the mass of cells is called an embryo and the three layers of cells are formed:

o Endoderm – inner layer of cells, which will develop into the digestive and respiratory systems.

o Ectoderm – outermost layer, which will become the nervous system, sensory receptors (ears, nose, and eyes, for example), and skin parts (hair and nails, for example).

o Mesoderm – middle layer, which will become the circulatory system, bones, muscles, excretory system, and reproductive system.

3. Fetal Period – begins two months after conception and lasts for seven months, on average.

TERATOLOGY AND HAZARDS TO PRENATAL DEVELOPMENT:

Teratogen – from the Greek word tera, meaning “monster.” Any agent that causes a birth defect. The field of study that investigates the causes of birth defects is called teratology.The dose, the time of exposure to a particular agent, and genetic susceptibility influence the severity of the damage to an unborn child and the type of defect that occurs.

Prescription and Nonprescription Drugso Prescription drugs that can function as teratogens

include anitbiotics; some antidepressants; certain hormones; and Accutane (prescribed for acne)

o Nonprescription drugs that can be harmful include diet pills, aspirin, and caffeine.

Psychoactive Drugs – drugs that act on the nervous system to alter states of consciousness, modify perceptions, and change moods.

o Alcohol Fetal alcohol syndrome – a cluster of

abnormalities that appears in the offspring of mothers who drink alcohol heavily during pregnancy.

o Nicotine

Illegal Drugso Cocaine

Reduced birth weight, length, and head circumference; impaired motor development; lower arousal; less effective self-regulation, higher excitability; lower quality of reflexes; impaired information processing and language development; poor attentional skills; impaired processing of auditory information after birth; and neurological and cognitive deficits.

o Marijuana Impaired attention; smaller babies; learning

and memory difficulties at age 11.o Heroin

Behavioral difficulties and attention deficits

Incompatible Blood Types Environmental Hazards

o Radiation Gene mutation, chromosomal

abnormalities, microencephaly, mental retardation, and leukemia

o Environmental pollutants and toxic wastes: carbon monoxide, mercury, lead

Mental developmento Manufacturing chemicals known as PCBs

Visual discrimination and short term memory

o Sauna or hot tubs Fever, birth defects, even fetal deaths

Other Maternal factorso Infectious disease

Rubella (German measles) Mental retardation; blindness;

deafness; heart problems Syphilis (a sexually transmitted infection)

Damages organs after they have formed; eye lesions; skin lesions; problems in central nervous system and gastrointestinal tract.

Genital Herpes May die or brain damage

AIDS Destroys the body’s immune

systemo Nutritiono Emotional states and stresso Maternal age

Infants born to adolescents are often premature.

Infants born to 35 years and older have increased risk for low birth weight and for Down Syndrome.

Paternal factorso Exposure to lead, radiation, certain pesticides, and

petrochemicals may cause abnormalities in the sperm that lead to miscarriage or diseases, such as childhood cancer.

o Low vitamin C Cancer and birth defects

o Smoking Low birth weights and cancer

o Age Birth defects including Down Syndrome,

dwarfism, marfan sysndrome, which involves head and limb deformities.

BIRTHThe Birth Process

Stages of Birtho First stage lasts an average of 12 to 24 hours; it is the

longest of the three stages; Uterine contractions are 15 to 20 minutes apart at the beginning and last up to a minute.

o Second birth stage begins when the baby’s head starts to move through the cervix and the birth canal. Lasts approximately 1 ½ hours.

o Afterbirth is the third stage, at which time the placenta, umbilical cord, and other membranes are detached and expelled. The shortest of the three, lasting only minutes.

The Transition from fetus to Newborno Being born involves considerable stress for the baby.

The first breaths may be the hardest ones an individual takes.

Childbirth Strategieso Childbirth Setting and Attendants

o Methods of Childbirth

Medicated Analgesia – used to relieve pain.

Includes tranquilizers, barbiturates, and narcotics (such as Demerol).

Anesthesia – used in late first-stage labor and during expulsion of the baby to block sensation in an area of the body or to block consciousness. (epidural block, regional anesthesia that numbs the woman’s body from the waist down.)

Oxytocics – synthetic hormones that are used to stimulate contractions. (Pitocin, most commonly used).

Natural childbirth – 1914, Grantley Dick-Read: Its purpose is to reduce the mother’s pain by decreasing her fear through education about childbirth and by teaching her to use breathing methods and relaxation techniques during delivery.

Prepared childbirth – Ferdinand Lamaze: similar to natural childbirth but includes a special breathing technique to control pushing in the final stages of labor, as well as a more detailed anatomy and physiology course. Lamaze method, is where the pregnant woman’s husband or a friend usually serves as a coach, who attends childbirth classes with her and helps her with her breathing and relaxation during delivery.

Cesarean delivery – the baby is removed from the mother’s uterus through an incision made in her abdomen. Sometimes known as cesarean section or C-section. A cesarean section is usually performed if the baby is in a breech position, which causes the baby’s buttocks to be the first part to emerge from the vagina. Cesarean deliveries also are performed if the baby is lying crosswise in the uterus, if the baby’s head is too large to pass through the mother’s pelvis, if the baby develops complications, or if the mother is bleeding vaginally.

Low Birth Weight Infants: weigh less than 5 ½ pounds at birth.

Preterm infants: infants born three weeks or more before the pregnancy has reached its full term.

Small for date infants: also called small for gestational age infants, these infants’ birth weights are below normal when the length of pregnancy is considered. It may be preterm or full term.

o Kangaroo care: a way of holding a preterm infant so that there is skin-to-skin contact. Advantages: stabilize the heartbeat, temperature, and breathing; the mothers have more success with breastfeeding and improve their milk supply; have longer periods of sleep, gain more weight, decrease crying, have longer periods of alertness, and earlier hospital discharge.

o Infant massage: might play in improving the developmental outcome of preterm infants.

Measures of Neonatal Health and Responsiveness Apgar Scale: A widely used method to assess the health of

newborns at one and five minutes after birth. It evaluates infant’s heart rate, respiratory effort, muscle tone, body color, and reflex irritability.

Brazelton Neonatal Behavioral Assessment Scale: A test performed within 24 to 36 hours after birth to assess newborns’ neurological development, reflexes, and reactions to people.

Score 0 1 2Heart rate Absent Slow—less than

100 beats per minute

Fast—100-140 beats per minute

Respiratory effort

No breathing for more than 1 minute

Irregular and slow

Good breathing with normal crying

Muscle tone Limp and Flaccid Weak, inactive, but some flexion of extremities

Strong, active motion

Body color Blue and pale Body pink, but extremities blue

Entire body pink

Reflex Irritability No response Grimace Coughing,

sneezing, and crying

The Apgar Scale

Postpartum Period: The period after childbirth when the mother adjusts, both physically and psychologically, to the process of childbirth. This period lasts for about six weeks or until her body has completed its adjustment and returned to a near prepregnant state.

Physical Adjustments Involution: the process by which the uterus returns to its

prepregnant size five or six weeks after birth. Immediately following birth, the uterus weighs 2 to 3 ½ ounces.

The woman will probably begin menstruating again in four to eight weeks if she is not breastfeeding. If she is breastfeeding, she might not menstruate for several months to a year or more, though ovulation can occur during this time.

Physicians often recommend that women refrain from having sexual intercourse for approximately six weeks following the birth of the baby.

The mother can begin some exercises as soon as one hour after delivery such as relaxation techniques and slow breathing.

Emotional and Psychological Adjustments Here are some signs that can indicate a need for professional

counseling about postpartum adaptation:o Excessive worryingo Depressiono Extreme changes in appetiteo Crying spellso Inability to sleep

Postpartum depression: characteristics of women who have such strong feelings of sadness, anxiety, or despair that they have trouble coping with daily tasks in the postpartum period.

Bonding: the formation of a close connection, especially a physical bond between parents and their newborn, in the period shortly after birth.

REFLECTION:

1. What can be done to convince women who are pregnant not to smoke or drink? Consider the role of health-care providers, the role of insurance companies, and specific programs targeted at women who are pregnant.

2. If you are a female, which birth strategy do you prefer? Why? If you are a male, how involved would you want to be in helping your partner through pregnancy and the birth of your baby?

3. If you are a female, what can you do to adjust effectively in the postpartum period? If you are a male, what can you do to help in the postpartum period?

Reference: Santrock, J.W. (2006). Life-Span Perspective.10th Edition. McGraw-Hill. New York.

Prepared by:Mrs. Maria Angela L. DiopolInstructor