Infants and Children in Context. Tara L. Kuther

67

       Vernix caseosa 67

       Age of viability 67

       Teratogen 68

       Sleeper effects 69

       Fetal alcohol spectrum disorders 71

       Fetal alcohol syndrome (FAS) 71

       Spina bifida 75

       Anencephaly 75

       Prenatal care 77

       Labor 79

       Breech position 81

       Cesarean section 81

       Natural childbirth 81

       Doula 81

       Apgar scale 83

       Brazelton Neonatal Behavioral Assessment Scale (NBAS) 83

       States of arousal 84

       REM sleep 84

       Preterm 85

       Small for date 85

       Low birthweight 85

       Very low birthweight 85

       Extremely low birthweight 85

       Kangaroo care 88

      Summary

       3.1 Describe the three periods of prenatal development.Conception occurs in the fallopian tube. During the germinal period, the zygote begins cell division and travels down the fallopian tube toward the uterus. During the embryonic period from weeks 2 to 8, the most rapid developments of the prenatal period take place. From 9 weeks until birth, the fetus grows rapidly, and the organs become more complex and begin to function.

       3.2 Explain how exposure to teratogens and other environmental factors can influence the prenatal environment.Teratogens include diseases, drugs, and other agents that influence the prenatal environment to disrupt development. Generally, the effects of exposure to teratogens on prenatal development vary depending on the stage of prenatal development and dose. There are individual differences in effects, different teratogens can cause the same birth defect, a variety of birth defects can result from the same teratogen, and some teratogens have subtle effects that result in developmental delays that are not obvious at birth or not visible until many years later. Prescription and nonprescription drugs, maternal illnesses, and smoking and alcohol use can harm the developing fetus. Prenatal development can also be harmed by factors in the environment.

       3.3 Summarize the process of childbirth.Childbirth progresses through three stages. The first stage of labor begins when the mother experiences regular uterine contractions that cause the cervix to dilate. During the second stage, the fetus passes through the birth canal. The placenta is passed during the third stage. Medication is used in most births, often in combination with breathing and relaxation techniques characteristic of natural births. About one-third of U.S. births are by cesarean section.

       3.4 Discuss the neonate’s physical capacities, including development in low-birthweight infants.Developmental researchers now know that the newborn is more perceptually competent than ever imagined. The most well-developed sense is audition. Newborns display regular cycles of eating, elimination, and states of arousal or degrees of wakefulness, spending about 50% of their sleep time in REM, thought to permit the brain to stimulate itself. There are two types of low-birthweight infants, those who are preterm and those who are small for date. Low-birthweight infants struggle to survive. Low-birthweight infants experience higher rates of sensory, motor, and language problems as well as learning disabilities, behavior problems, and deficits in social skills into adolescence. The long-term outcomes of low birthweight vary considerably and depend on the environment in which the children are raised.

      Review Questions

       3.1 What are the three periods of prenatal development?What major milestones occur in each period?What are influences on prenatal care?

       3.2 Define and provide three examples of teratogens.What are four principles that determine the effects of exposure to teratogens during prenatal development?

       3.3 What are the three stages of childbirth?Describe characteristics of each stage.What are the differences among cesarean delivery, natural childbirth, and home birth?

       3.4 How are neonates assessed at birth?Describe the neonate’s perceptual capabilities.What are two types of low-birthweight infants?What factors determine long-term outcomes for low-birthweight babies?

      Descriptions of Images and Figures

      Back to Figure

      The parts labelled in the illustration are as follows.

       Ovaries

       Fallopian tube

       Follicles

       Corpus luteum

       Uterus

       Uterine wall

       Cervix

       Vagina

      Back to Figure

      The parts labelled are as follows.

       Ovary

       Corpus luteum[EI1]

       Developing follicles

       Ovulation

       Fallopian tube

       Fertilization (near the head of the Fallopian tube)

       Cell division begins

       Morula (where it enters the uterus)

       Blastocyst with a noticeable inner cell mass

       Implantation

      Back to Figure

      The details of the chart are as follows.

      Weeks 1 and 2

       Period of dividing zygote, implantation, and bilaminar embryo

       Not susceptible to teratogenesis

       Death of embryo and spontaneous abortion common

      Weeks 3 to 8: Main embryonic period (in weeks)

       Period of major congenital anomalies

      Weeks 9 to 38: Fetal period (in weeks)

       Period of functional defects and minor anomalies

      Less Sensitive period:

       Neural tube defects: weeks 3 to 6

       Mental retardation: weeks 7 to 16

       T A, A S D, and V S D: third week to sixth week

       Amelia/Meromelia: weeks 4 to 5

       Cleft lip: weeks 5 and 6

       Low-set malformed ears and deafness: weeks 4 to 9

       Microphthalmia, cataract, glaucoma: weeks 4 to 8

       Enamel hypoplasia and staining: weeks 7 and 8

       Cleft palate: weeks 7 to beginning of 9

       Masculinization of female genitalia: middle of 7th week to week 9

      Highly sensitive period:

       C N S: weeks 32 to 38

       Heart: end of week 6 to week 8