Lifespan Development

Lifespan Development Module # 3: Prenatal Development

Module Learning Outcomes Explore the journey of preparing for birth and the development process from the moment of conception to delivery 3.1: Explain the role of genetics in prenatal development 3.2: Explain the main stages of prenatal development 3.3: Describe approaches to childbirth and the labor and delivery process

Biological Foundations of Human Development

Learning Outcomes: Biological Foundations of Human Development 3.1: Explain the role of genetics in prenatal development 3.1.1: Explain the evolutionary psychology perspective of lifespan development 3.1.2: Describe genetic components of conception 3.1.3: Describe genes and their importance in genetic inheritance 3.1.4: Describe chromosomal abnormalities 3.1.5: Explain the value of prenatal testing 3.1.6: Describe the interaction between genetics and the environment 3.1.7: Compare monozygotic and dizygotic twins

Evolutionary Psychology • Evolutionary psychology focuses on how universal patterns of behavior and cognitive process have evolved over time • Evolutionary psychologists study a variety of psychological phenomena that may have evolved as adaptations • The theory of natural selection (Darwin) refers to the survival and reproduction of organisms better suited for their environment over those poorly suited • Evolutionary psychology enhances our understanding of development through how we choose mates and achieve reproductive success

Heredity and Chromosomes • There are two types of gametes involved in reproduction: male gametes (sperm) and female gametes (ova) • Male gametes are produced in the testes through spermatogenesis beginning at about 12 years of age • Female gametes are stored in the ovaries and are present at birth though immature with only about 400 becoming mature eggs • Once a ripened egg is released from the ovary, it moves into the fallopian tube and reaches the uterus in 3 to 4 days • Once a single sperm unites with the nucleus of the egg, a new cell with the combined genetic information from both parents, is a zygote • Chromosomes are long strings of genetic material known as deoxyribonucleic acid (DNA)

Heredity and Chromosomes, continued • DNA is a helix-shaped molecule made up of nucleotide base pairs [adenine (A), guanine (G), cytosine (C), and thymine (T) • Each chromosome has sequences of DNA make up genes that control a number of visible characteristics • Each gene has multiple variations or alleles (specific versions of genes) • In meiosis, segments of the chromosomes from each parent form pairs and genetic segments are exchanged as determined by change

Heredity and Chromosomes, continued • Each parent contributes half the genetic information carried by the offspring with the resulting characteristics determined by the interaction of parental genetic material • Genotype is the genetic makeup of the individual while the phenotype refers to the person’s inherited physical characteristics • 22 of chromosomes from each parent are similar in length to a corresponding chromosome from the other parent with the remaining chromosome looks like an X or Y (XY: male; XX: female) • Genetic inheritance of traits for humans is based upon Gregor Mendel’s model of inheritance • Genes on autosomes (any chromosome other than a sex chromosome) have alleles and their associated traits are autosomal dominant or autosomal recessive

Genetic Variation and Inheritance Dominant genes are expressed while recessive genes are only expressed in the absence of a dominant gene If a person has only one recessive gene for a disease, they would be a carrier (i.e., cystic fibrosis) Someone is homozygous for an allele when they have two copies of the same allele and heterozygous when they have a combination of alleles Harmful genes like cystic fibrosis come from a gene mutation, or a sudden permanent change A Punnett Square

Chromosomal Abnormalities and Genetic Testing Chromosomal abnormalities occur when the chromosome structure is altered and includes: Deletions – portion is missing or deleted Duplications – portion is duplicated Translocations – portion is transferred to another Inversions – portion has broken off and reattached upside down Insertions – portion has been deleted and inserted into another chromosome Rings – portion has broken off and formed a circle Isochromosome – formed by the mirror image copy of a chromosome segment Figure 1. The three major single-chromosome mutations: deletion (1), duplication (2) and inversion (3).

Chromosomal Abnormalities and Genetic Testing, continued One of the most common chromosomal abnormalities is on pair #21, down syndrome A chromosomal abnormality on #23 results in a sex-linked chromosomal abnormality Turner syndrome occurs in 1 of 2,500 live female births when an ovum lacking a chromosome is fertilized by a sperm with an X chromosome, resulting in a zygote with an XO composition Klinefelter syndrome (XXY)occurs in 1 out of 700 live male births and results when the ovum containing an extra X chromosome is fertilized by a Y sperm

Prenatal Testing • Prenatal screening focuses on finding problems among a large population with affordable and noninvasive methodsand commonly includes ultrasounds, blood tests, and blood pressure readings • Prenatal diagnosis focuses on pursuing additional detailed information once a particular problem has been found and can be invasive • Screening can detect problems such as neural tube defects, anatomical defects, anatomical defects, chromosomal abnormalities, and gene mutations • Prenatal diagnosis is intended to enable timely medical or surgical treatment of a condition, to give parents the change to abort a fetus, and to give parents the chance to better prepare for a baby with special needs

Behavioral Genetics • The ”nature/nurture” debate questions the role of heredity versus environment in our personality • Most scholars agree that there is a constant interplay between nature and nurture • While genetic predispositions are important, other factors are in part the effect of epigenetic, above the genome, changes • Epigenetics describe psychological development as the result of an ongoing, bi-directional interchange between heredity and the environment • Behavioral genetics is the science of how genes and environments work together to influence behavior and can be studied in adoption studies and twin studies

Behavioral Genetics, continued • Monozygotic twins occur when a single zygote or fertilized egg splits apart in the first two weeks of development and creates two separate but identical offspring • Dizygotic or fraternal twins share the same genetic material as would any other children with the same mother and father • In the uterus, 60-70% of monozygotic twins share the same placenta (a temporary organ connecting the fetus to the uterine wall) but separate amniotic sacs (a thin but tough transparent pair of membranes that hold a developing embryo/fetus until shortly before birth) • Conjoined twins: monozygotic twins whose bodies are joined during pregnancy • Vanishing twins: as many as 1 in 8 pregnancies start out as multiples but only a single fetus is brought to full term • Twin studies: a behavior genetic research method that involves a comparison of the similarity of monozygotic and fraternal twins

Practice Question 1 Shelby is talking with her doctor about prenatal screening. She wants to know what will be covered in the screening. Which of the following is not a condition prenatal screening tests routinely screen for? • genetic diseases • birth defects • cancer • chromosomal abnormalities

Practice Question 2 Which of the following is not considered a recessive trait or disease? • red hair • nearsightedness • Huntington disease • male pattern baldness

Prenatal Development

Learning Outcomes: Prenatal Development 3.2: Explain the main stages of prenatal development 3.2.1: Differentiate between development during the germinal, embryonic, and fetal periods 3.2.2: Examine risks to prenatal development posed by exposure to teratogens 3.2.3: Explain potential complications of pregnancy and delivery

Periods of Prenatal Development • The Germinal Period (Weeks 1-2) • The fertilized egg forms a zygote as a one-cell structure • The genetic makeup and sex of the baby are set • During the first week, the zygote divides and multiplies through process of mitosis for about 7-10 days and has 150 cells then implants into the uterine lining • The Embryonic Period (Weeks 3-8) • Upon implantation, the multi-cellular is called an embryo • The placenta, a structure connected to the uterus to provide nourishment and oxygen from the mother to the embryo via the umbilical cord, is formed • Cells continue to differentiate, the heart starts beating, organs begin to form and function • Growth occurs from head to tail(cephalocaudal) and from the midline outward (proximodistal) • About 20% of organisms fail during the embryonic period

Periods of Prenatal Development, continued • The Fetal Period (Weeks 9-40) • Fetus (at about 9 weeks), about the size of a kidney bean and begins to look human • By 12 weeks, the fetus has all body parts • By 16 weeks, the fetus is about 4.5 inches long with fully developed fingers and toes and visible fingerprints • Organ systems continue to develop and rudimentary neurons in the brain are developed by 24 weeks • The age of viability is reached at about 22 to 26 weeks • By week 37 all of the fetus’s organ systems are developed enough that it could survive outside the mother’s uterus without risks associated with premature birth

Environmental Risks • The developing child is most at risk for severe problems in the first three months • Teratogens are factors that can contribute to birth defects which include some maternal diseases, drugs, alcohol, and stress as well as environmental and occupational exposures • Alcohol: consumption particularly during the second month of prenatal development may lead to neurocognitive and behavioral difficulties that can last a lifetime and can frequently result in fetal alcohol spectrum disorders (FASD) • Tobacco: Nicotine levels travel through the placenta to the fetus and has been associated with low birth rate, placenta previa, birth defects, preterm delivery, fetal growth restriction, and sudden infant death syndrome

Environmental Risks, continued • Drugs: if prescription medication is required, the lowest possible dose should be used • Illicit drugs can cause low birth-weight, withdrawal symptoms, birth defects, or learning and behavioral problems • Environmental Chemicals: can include an exposure to a wide array of agents including pollution, organic mercury compounds, herbicides, and industrial solvents • Sexually Transmitted Infections: can complicate pregnancy and may have serious effects on both the mother and developing baby • Maternal Diseases: maternal illness increases the chance that a baby will be born with a birth defect or have a chronic health problem • Maternal Stress: Because of a link in blood supply between mother and fetus, stress can leave lasting effects on a developing fetus

Environmental Risks, continued • There are several considerations in determining the type and amount of damage that might result from exposure to a teratogen • Timing of exposure: if a substance is introduced during a particular bodily structure’s critical period of development, damage may be greater • Amount of exposure: Some substances are not harmful unless the amounts reach a certain level • Genetics: genetic make-up plays a role in the impact a particular teratogen might have on a child • Being male or female: Males are more likely to experience damage due to teratogens than females

Complications of Pregnancy and Delivery • Minor side effects of pregnancy are potentially very uncomfortable and include nausea, heartburn, gas, hemorrhoids, backache, leg cramps, insomnia, constipation, shortness of breath, or varicose veins • Major complications can pose health risk to the mother and child and often require special care: • Gestational diabetes • Hyperemesis gravidarum • Preeclampsia • Deep vein thrombosis • Increased susceptibility to infections • Peripartum cardiomyopathy

Maternal Mortality • About 830 women die from preventable pregnancy or childbirth-related complications around the world every day • Almost all maternal deaths (99%) occur in developing countries • The lifetime risk of maternal death in high-income countries is 1 in 3,300 compared to 1 in 41 in low-income countries • A pregnancy-related death is the death of a woman while pregnant or within 1 year of the end of a pregnancy, regardless of the outcome, duration, or site of the pregnancy, from any cause related to or aggravated by the pregnancy or its management • Top causes of pregnancy-related deaths include cardiovascular disease, non-cardiovascular diseases, and infection or sepsis • Spontaneous abortion, miscarriage, is experienced in approximately 20-40% of undiagnosed pregnancies and in 10% of diagnosed pregnancies and typically occurs before the 12th week of pregnancy

Practice Question 3 What is the number one cause of pregnancy-related death in the United States? • Hemorrhage • Sepsis • Preeclampsia • Cardiovascular diseases

Class Activity: Prenatal Screening • Get into groups and have someone in charge of writing down main discussion points for the following questions: • What are the pros and cons of receiving prenatal screening tests? • Why might some mothers decide not to have these tests? • Once you have several discussion points, create your argument either in favor of or against prenatal screening • As a group, present your argument to the class

Birth and Delivery

Learning Outcomes: Birth and Delivery 3.3: Describe approaches to childbirth and the labor and delivery process 3.3.1: Describe various approaches to childbirth 3.3.2: Describe a normal delivery, including the stages of childbirth 3.3.3: Examine risks and complications with newborns

Childbirth • Mongan Method or HypnoBirthing(Dick-Read method) emphasizes relaxation and proper breathing with contractions as well as family support and education • The Lamaze Method emphasizes the woman to be in control of delivery through muscle relaxation, breathing through contractions, having a focal point during contractions, and having a support person • The Bradley Method helps women deliver naturally with few or no drugs emphasizing excellent nutrition and exercise, relaxation techniques for pain, and the partner as coach • Nurse Midwives assist with deliveries for women who are at low risk for birth complications at home, in a birthing center, or hospital • Home Births are most common for women who have had previous children, are over 25, and who are white

Childbirth, continued • Birthing Centers present a more home-like environment than a hospital labor ward with more options during labor and decor meant to emphasize the normality of birth • Water birth can help alleviate discomfort and pressure for the mother and can include laboring and/or giving birth in a warm tub of water Hospital birth is the most common and can include either natural pain relief methods or medications and medical interventions that relieve pain, such as an epidural or inhaled nitrous oxide

Process of Delivery • The first stage of labor is typically the longest with uterine contractions initially lasting about 30 seconds 15 to 20 minutes apart but increasing in duration and frequency to more than a minute and 3 to 4 minutes apart • During the first stage, the cervix dilates to 10 centimeters or just under 4 inches and take 12-16 hours for first children and 6-9 hours for women who have previously given birth • The second stage involves the passage of the baby through the birth canal and take about 10-40 minutes with the head delivering first and the umbilical cord clamped and cut • The third stage is relatively painless when the placenta is delivered and occurs within 20 minutes after delivery of the baby • Cesarean section is the use of surgery to deliver babies and may be necessary when vaginal delivery poses a risk to baby or mother

Newborn Assessment and Risks • The Neonatal Behavioral Assessment Scale (NBAS) assesses the baby’s motor development, muscle tone, and stress response • APGAR: conducted 1 to 5 minutes after birth and measures the heart rate, respiration, muscle tone, reflex response, and color on a score of 0 to 2 with any total scores 5 or under being a cause for concern • Low birth weight is less than 5.8 pounds, resulting in difficulty maintaining body temperature and higher infection risk • Premature birth is less than 37 weeks gestation and can be triggered by anything that disrupts the mother’s system • A lack of adequate (hypoxia) or complete (apoxia) oxygen shortly after birth can lead to brain damage and other disorders and is typically caused by umbilical cord problems, birth canal problems, blocked airways, and placenta abruption

Practice Question 4 Which stage of labor is typically the longest? • The first stage • The second stage • The third stage • They are all the same length

Class Activity: Ethics and Pregnancy • Get into groups and have someone in charge of writing down main discussion points • Discuss the ethics of using medical technology during pregnancy • Consider when prenatal intervention is ethical and when it is not • Support your ideas with current research • Create a short presentation to present to the rest of the class

Quick Review • What is the evolutionary psychology perspective of lifespan development? • What are the genetic components of conception? • What is the importance of genes in genetic inheritance? • How do chromosomal abnormalities occur and what are the most common? • What is the value of prenatal testing? • How do genetics and the environment interact? • How are monozygotic and dizygotic twins different? • How does development differ during the germinal, embryonic, and fetal periods? • What are the risks to prenatal development posed by exposure to teratogens? • What are potential complications of pregnancy and delivery? • What are various approaches to childbirth? • What does a normal delivery involve, including the stages of childbirth? • What are the risks and complications with newborns?

Lifespan Development