Stages of Prenatal Development

 

Stages of Prenatal Development

ConceptionGerminalEmbryonicFetal

Conception

Conception occurs 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

Infertility

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

Causes of male infertility involve the quantity or strength of sperm produced.

Infertility (2)

Causes of female infertility involve structural abnormalities in the Fallopian tubes or uterus or a failure to ovulate and release mature eggs.

New technologies are now available to help overcome infertility

The Germinal Stage (first two weeks)

1. The blastocyst is differentiated into three layers: the ectoderm, the endoderm, and the mesoderm.

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

3. The embryonic stage begins with implantation, and the fully implanted blastocyst is referred to as the embryo.

Blastocyst at day six

Another blastocyst, day six

Embryonic Stage (3rd through 8th weeks)

1. Growth in the embryonic and fetal stages follows a cephalocaudal (head-to-tail) pattern and a proximodistal (near-to-far) pattern.

2. The head, blood vessels, heart, and most vital organs begin to develop before the arms, legs, hands, and feet.

Early Embryonic Stage

Embryonic stage (slide 2)

•3. The placenta forms as an area of the uterine wall through which oxygen and nutrients reach the fetus.

•4. The umbilical cord connects the embryo to the placenta and provides nutrients and carries away waste products.

•5. The amniotic sac surrounds the embryo and protects it.

Later embryonic stage

Fetal Stage (9th to birth)1. The fetal stage is marked by

the development of the first bone cells. The embryo is now called the fetus.

2. By the third month, the fetus is able to move its head, legs, and feet. By the fourth month, the mother may feel quickening, or fetal movement.

3. The beginning of the seventh month is considered the age of viability.

4. At the end of nine months, the fetus weighs on average 7.5 pounds and is almost 20 inches long.

Fetus at 12 weeks

Fetus at 18 weeks

The experience of pregnancy

1. Physical complaints such as nausea are common.

2. Normal weight gain is about thirty pounds and is dispersed in organs, baby, and bodily fluid.

3. Changes in the woman's body bring mixed feelings.

Prenatal influences on the child

A. Key concepts– 1. Canalization is seen

in prenatal development.– 2. Drugs and other

harmful environmental influences can also canalize development, usually in negative ways.

– 3. Risk factors can interfere with canalized processes that lead to the development of specific organs.

Maternal diet and nutrition

1. Poor nutrition leads to specific physical deformities and increased risk for prematurity and infant mortality; later nutritional deprivation leads to a reduced number of brain cells.

2. Pregnant women should eat between two hundred and one thousand calories more per day, adding mainly carbohydrates and protein.

Prenatal health care (1 of 2)

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

2. There are racial differences in adequacy of care.

3. Special programs have been implemented in communities to help high-risk mothers.

Prenatal health care (2)

Stress

1. Prolonged anxiety just before or during pregnancy increases the likelihood of medical complications.2. Emotional stress is related to spontaneous abortion as well as to labor and birthing problems.

The birth episode

BirthAfter about thirty-eight weeks in the

womb, the baby is considered "full term," or ready for birth. Fetal presentation refers to the body part closest to the mother's cervix. There are three types of presentation: Cephalic (normal), breech, and transverse.

Stages of labor•1. During the last weeks of

pregnancy, it is common for the mother to experience false labor, or Braxton-Hicks contractions.

•2. The first stage of labor usually begins with relatively mild contractions, leading to stronger contractions and the dilation of the cervix to accommodate the baby's head (10 centimeters).

Stages of labor3. Toward the end of the first stage, which may take from eight to twenty-four hours, a period of transition begins, and the baby's head begins to move through the birth canal.4. The second stage of labor is from complete dilation of the cervix to birth, lasting about one to one and one-half hours.5. During the third stage of labor, which lasts only a few minutes, the afterbirth (consisting of the placenta and umbilical cord) is expelled

Childbirth settings and methods

Traditionally, childbirth was attended by a midwife and was seen as a natural process. With the advent of modern technology, births increasingly took place in medical settings. This resulted in decreased mortality rates, but birth was now seen as a medical event controlled by physicians.

1. Hospital births. Birthing rooms are becoming more popular in hospitals.2. Non-hospital settingsa. Freestanding birth centers are non-hospital facilities that provide family centered maternity care.b. Birth centers have lower rates of Caesarean sections.c. Home births are another alternative for pregnancies predetermined to be low risk.3. Prepared childbirth. Methods of prepared childbirth help parents rehearse the sensations of labor.

Programs emphasize educational, physical, and emotional preparation for the birth process and use of a coach.

b. Women who participate in birthing programs report favorable effects.

c. Leboyer claimed a gentle birth has benefits for the child.

Lamaze birth philosophyIntegral to the work of Lamaze International is a fundamental philosophy of birth:

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.

Medicinal aids to birthDespite good psychological preparation, the

mother may experience considerable pain, which can be made bearable through pain-reducing drugs such as narcotics or other sedatives.

a. The most common anesthetics are epidural and spinal, which allow the mother to remain awake and alert during birth.

b. A general or local anesthetic delays the recovery of the mother as well as the bonding between mother and child.

Pain in childbirth

5. Perceptions of pain during childbirth

a. It is difficult to determine how much discomfort or distress a laboring woman is in and how to respond appropriately.b. There are cultural differences in the perceptions of pain.

Problems during labor and delivery (1 of 3)

1. Faulty power is the failure of the uterus to contract strongly enough to make labor progress to an actual delivery. Induced labor can be stimulated by the hormone oxytocin.

2. A faulty passageway condition occurs when the placenta develops so close to the cervix that it blocks the baby's passage down the birth canal during labor. This condition is called placenta previa.

Problems with Labor and Delivery (2 of 3)

3. A faulty passenger condition occurs when problems exist with the baby's position or size. Usually babies enter the birth canal head first, but occasionally one turns in the wrong direction during contractions. Forceps sometimes are used to remedy the situation.4. In a Caesarean section, the mother receives a general anesthetic and the baby is removed surgically. Techniques for this surgery have improved; however, a common criticism is that too many Caesareans are performed.

Problems with Labor and Delivery (3 of 3)

To deal with such problems, in most hospitals, electronic fetal monitoring is used to record uterine contractions and the fetal heart rate.

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 health problems

Pre-term Babies

Formerly called premature

More than three weeks before due date

At risk for respiratory distress syndrome (RDS)

Extended oxygen use=Retinopathy of Prematurity

Negative Prenatal Influences on the Child

Window of opportunity concept--critical time of vulnerability

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

Teratogenic Medicinal drugs

Thalidomide is a sedative, also an anti-nausea drug--but deforms children.

Diethylstilbestrol (DES) was used to prevent miscarriages but causes damage to reproductive systems of offspring.

Other potentially harmful prescribed drugs are accutane, streptomycin, and tetra-cycline.

Teratogenic non-medicinal drugs (1 of 3)

MarijuanaActive ingredient is

tetrahydra-conabaninol or THC

Is stored in fatty tissues of body

Placenta is no barrierBabies are born with

psych. if not physical addiction

Heroin

An opiate not totally unlike morphine, but more addictive

Severe withdrawal symptoms

Newborn babies of heroin addicts vomit, tremble, cry, and have fever, disturbed sleep, and abnormal cries

Fetal alcohol syndrome

CNS damage, heart defects, small head, distortion of joints, and abnormal facial features

Are evident in their inability to pay attention or maintain attention

Tobacco

Nicotine and carbon monoxide interfere with fetal oxygen supply

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

Maternal Diseases (1 of 2)

Rubella, or German measles. Disastrous in first trimester.

Syphilis and gonorrhea. Blindness, jaundice, anemia, pneumonia, skin rash, early death. Silver nitrate in the eyes.

Genital herpes. (1) Disease of skin and mucous membranes, or (2) blindness, permanent brain damage, seizures, and developmental delay.

Maternal diseases (2 of 2)

Cytomegalovirus (CMV). High risk for infants; jaundice, microcephaly, deafness, and eye problems.

Toxoplasmosis. Parasite from uncooked meat and cat feces. Low birth weight, enlarged liver and spleen, microcephaly, anemia, and calcifications in the brain.

Pediatric AIDS.

Home Factors

Teenage Pregnancy“Babies having

babies”--own growth is not complete

Pelvic cradle not ready

Threat to educationResponsibility not yet

learnedMaternal malnutrition

Domestic ViolenceSeven to Eight

percent of pregnant women are beaten by partners; most more than once

High rate of miscarriage