Chapter 4 Prenatal Development and Birth Summary

1.0 Images of Life-Span Development: Jim and Sara, an Expectant Couple

Couples expecting their first child spend much time preparing for the birth and face many difficult questions.

2.0 Prenatal Development

The Course of Prenatal Development. Prenatal development includes the germinal, embryological, and fetal periods. Conception usually occurs when a sperm cell unites with an ovum in the female's fallopian tube. The first two weeks of gestation is the germinal period, during which the zygote, a structure of 100 to 150 cells forms. The inner layer is the blastocyst that later develops into the embryo. The outer layer is the trophoblast that later develops into the placenta.

The implantation of the blastula marks the beginning of the embryological period. During the next six weeks, the embryo differentiates into an outer layer (ectoderm), a middle layer (mesoderm), and an inner layer (endoderm). The ectoderm becomes the hair, skin, nails, nervous system, and sensory receptors. The mesoderm becomes the muscles, bones, circulatory, and excretory systems. The endoderm develops into the digestive and respiratory systems. During the embryological period, a primitive human form takes shape, and the basic parts of the body can be identified. The placenta, umbilical cord, and amnion form and serve as a life-support system. The process of organ formation during the embryological period is called organogenesis. The embryological period ends at about eight weeks after conception.

The remaining seven months until birth is the fetal period. During this time, fetal size increases, the organs start functioning, reflexes appear, and there is sexual differentiation.

Miscarriage and Abortion. Miscarriages, or spontaneous abortions, happen when pregnancy ends before the developing organism is mature enough to survive outside the womb. Most occur within the first trimester without the mother's knowledge. Estimates indicate that 15 to 20 percent of pregnancies end in miscarriages. Deliberate termination of pregnancy is legal in the United States and can be done up until the end of the second trimester. The issue of induced abortion raises many medical, psychological, and social concerns and questions. Although abortion policies differ throughout the world, there is approximately one abortion for every two births. An unwanted pregnancy is stressful for the woman regardless of how it is resolved.

Teratology and Hazards to Prenatal Development. Teratology is the field that investigates the causes of congenital (birth) defects. Any agent that causes birth defects is called a teratogen; teratogens have their greatest effects during organogenesis.

Maternal diseases can cross the placental barrier or act at the time of birth. The maternal diseases and conditions believed to be involved in possible birth defects include rubella, syphilis, genital herpes, AIDS, the mother's age, nutrition, and emotional state and stress.

In the early 1960's mothers who took thalidomide, a tranquilizer for morning sickness, subsequently bore many deformed babies and demonstrated the powerful effects of drugs on prenatal development. Women who consume alcohol during pregnancy increase the likelihood of producing offspring with fetal alcohol syndrome. Smoking cigarettes is associated with adverse prenatal development, birth, and postnatal development. In addition, women who smoke during pregnancy experience more fetal and neonatal deaths, and have more preterm and low-birthweight infants. Other hazardous drugs include marijuana, heroin, and cocaine. Recent attention has centered on babies born to mothers who use cocaine.

Various environmental hazards can endanger the fetus. For example, exposure to radiation can cause chromosomal abnormalities. Pollutants and toxic wastes such as pesticides, carbon dioxide, mercury, and lead pose dangers to fetuses. A newer concern is with the effects of electromagnetic radiation from video display terminals. Toxoplasmosis produces coldlike symptoms in adults, but acts as a teratogen for a developing fetus. Saunas and hot tubs that raise the mother's body temperature can produce fevers that endanger the fetus.

3.0 Birth

Stages of Birth. The birth process has been divided into three stages. In the first stage, uterine contractions dilate the woman's cervix so that the baby can move from the uterus into the birth canal. The second stage begins when the baby's head starts to move through the birth canal and ends when the baby is born. The third stage, called afterbirth, involves the detachment and expulsion of the placenta.

Delivery Complications. A baby can move through the birth canal too rapidly or too slowly. A delivery that is too fast is called precipitate; when delivery is too slow, anoxia may result. The breech position occurs when the baby's head does not emerge from the vagina first. Surgical removal of the baby from the uterus is called a cesarean section.

The Use of Drugs During Childbirth. Drugs can aid deliveries by relieving pain or anxiety. Drugs such as the hormone oxytocin can speed the process of delivery. It is difficult to make clear statements about drug effects because birth weight and social class are better predictors of problems than drugs. Some medications are thought to have negative effects on the infant; others are thought to have no effect; however, the amount of medication is quite an important variable.

Childbirth Strategies. Expectant parents can choose from a number of childbirth strategies. In standard childbirth, an expectant mother goes to a hospital where a doctor becomes responsible for the baby's delivery. The birth usually takes place in a space resembling an operating room, and medication is commonly administered to the mother. Critics of this method point out that other individuals important to the mother are excluded from the process, the infant is separated from, the mother shortly after birth, and giving birth is treated like a disease. The LeBoyer method, often deemed "birth without violence," was intended to make the process of birth less stressful for infants. Prepared, or natural childbirth, is a process in which the mother is informed about what will happen during the procedure and about how she may best remain comfortable during childbirth, entails little medication, and involves parents in making decisions about any complications that arise. Although there are variations (e.g., the Lamaze method), all share common concerns for making parents confident, providing self-help tools for normal childbirth, and explaining how the medical system functions. This approach endorses both the teaching and taking of childbirth classes. The most current trend in the 1990's shifts emphases, offers new choices, and encourages understanding of obstetrical terminology.

Fathers now increasingly participate in the childbirth process. A cultural change in America encourages fathers to meet with caregivers, attend childbirth classes, and participate in the care of infants. Parents expecting a second or subsequent child often prepare older children for the birth of a sibling. The older child learns about pregnancy, birth, and life with a newborn in a developmentally appropriate fashion.

Preterm Infants and Age-Weight Considerations. Normal gestation is 38 to 42 weeks from conception. Infants born earlier than 38 weeks after conception are called preterm babies. Full-term infants born after a normal gestation period but who weigh less than 5.5 pounds are called low-birth , .lit infants. Intervention programs now improve the developmental outcomes for low-birthweight infants. Preterm infants have a different profile than that of full-term infants.

Care of the preterm infant is much too complex to be described only in terms of amount of stimulation. The conceptual age, illness, and Individual make of preterm infants affect their responses to stimulation. The appropriate stimulation changes as the preterm infant becomes less fragile and approaches full-term. Intervention programs should entail individual developmental plans.

Four important conclusions about preterm infants include: (a) advances in intensive care technology have reduced the likelihood of serious consequences for preterm infants, (b) outcomes for infants born with an identified problem are likely to be worse than for those born without a recognizable problem, and (c) more favorable outcomes for preterm infants are associate .with higher socioeconomic status.

Measures of Neonatal Health and Responsiveness. The Apgar Scale is a quick screen of inf. r .status that assesses heart rate, respiratory effort, muscle tone, body color, reflex irritability at one and five minutes after birth. The Brazelton Neonatal Assessment Scale is a more detailed long-term neurological evaluation, typically given on the third day of life and repeated later. It evaluates 20 reflexes and an infant's reactions to 27 different circumstances involving both physical and social stimulation. Brazelton training involves using the Brazelton Scale to show parents how their newborn responds to people. The training may be of help with high-risk infants.

4. The Postpartal Period

The Nature of the Postpartal Period. The postpartum period, usually lasting about six weeks after birth, comprises a time in which a woman's body adjusts both physically and psychologically to the process of childbearing. The term "fourth trimester" conveys the idea of continuity and the importance of this period for the mother.

Physical Adjustments. Physical adjustments include fatigue, involution (the process by which the uterus returns to its prepregnant size), consideration of when to resume sexual intercourse, and participation in exercises to recover former body contour and strength.

Emotional and Psychological Adjustments. Emotional fluctuations are common for recent mothers during the postpartal period. A special interest in the parent-infant relationship concerns bonding, the development of an emotional tie between parents and infant. In recent years, a critical-perk hypothesis has been advanced, suggesting that bonding must occur within the first few days of life. Although the exact time period has been questioned, this view has led to a revision of hospital procedures, allowing mothers and fathers more access to their infants in hospitals than was previously permitted.

4. Contemporary Concerns

Sociocultural Worlds of Development 4.1: Prenatal Care in the United States and around the World. The effectiveness of prenatal care is reflected by the percentage of low-birthweight infants. The United States has the highest percentage of low-birthweight infants among the economically and technologically advanced countries of the world. This outcome likely results from a lack of a national health care policy that ensures care for pregnant women.

Sociocultural Worlds of Development 4.2: To Work or Not to Work. New babies prompt families to consider whether and when a recent mother should go back to work. Guidelines for making the decision to work or not to work exist.

Perspectives on Parenting and Education 4.1: Becoming Knowledgeable about Pregnancy, Prenatal Development, and Childbirth Strategies. Learning about pregnancy and prenatal development and learning about childbirth strategies are two important aspects of education for expectant parents. Expectant parents often can benefit from parent education classes that cover topics such as self-care, fetal development, sexuality, nutrition, rest, and exercise. Childbirth class help an expectant couple learn about labor, birth, and how to cope with the final stage of pregnancy.

Life-Span Practical Knowledge 4.1: What to Expect when You're Expecting. This book provides a step-by-step guide to pregnancy and childbirth. This book is excellent and reassuring to expectant parents.

Life-Span Practical Knowledge 4.2: Will it Hurt the Baby? Richard Abrams book discusses how to use medicines safely during pregnancy and breast feeding.

Life-Span Health and Weil-Being: The Power of Touch and Massage in Development. Research by Tiffany Field has produced interest in the roles of touch and massage in improving the growth, health, and well-being of infants and children. Massage facilitates weight gains for preterm babies. Touch has been helpful also with children and adolescents who have touch aversions deriving from sexual abuse, autism, and eating disorders.