Human Dev LVL 5
Amniocentesis: Sampels amniotic fluid surrounding fetus, conducted 15-18th week
Pros & Cons:
Risk of miscarriage, invasive treatment
Able to genetically analyze fetus and get results within a timely manner
Chorionic Villus Sampling: Samples tissue for the chorion, conducted 9-12 weeks
Pros & Cons:
Invasive procedure, higher risk of miscarriage (.5-1%), can't be used prior to 10 weeks can lead to limb defects and miscarriages
Noninvasive Prenatal Testing: takes blood sample from mother to examine cell-free DNA, conducted 10-22 weeks
Pros & Cons:
No risk to the offspring
Fairly new, less accurate than amniocentesis or chronic villus sampling in detecting genetic abnormalities
Level 5 The Antenatal Imaging Apparatus
Ovulation:
Women’s cycle measured between the first day of period from one month to the first day of her period the next month
Ovulation occurs around 14th day, ovaries release an Ovum, a mature egg into the fallopian tube, release triggered by luteinizing hormone, or LH
Any sperm present in reproductive system has about 12-24 hours after ovulation to fertilize ovum before it perishes
Women are born with all eggs she’ll ever have, 1-2 million
The Germinal Period:
First two weeks of prenatal development
Fertilization:
When sperm and egg fuse to create a single cell, The Zygote
Most likely fertilized in the fallopian tubes
Zygote:
Single cell that is created by fertilization with two pronuclei
Morula:
Early cluster of germinal cells that has mulberry-like appearance
Result of mitosis occurring at rate of once every 12-24 hours, by day 4 have a cluster of about 16 cells
Blastocyst
Germinal cell differentiation that forms 3 layers
Trophoblast
Froms the umbilical cord and blood vessels of placenta
Produces blood cells until embryo’s liver develops
Forms amniotic sac, forms chorion
Blastocele
Allows for cell migration
Inner cell mass
Becomes embryo and eventually the fetus
Early in development, cells have ability to differentiate into any type of cell, called totipotency
Between 6-11 days, Blastocyst finds endometrium (inner uterine lining), trophoblast beings secreting enzymes that allow blastocyst to implant into endometrium, Human chorionic Gonadotropin begins to increase into sufficient levels to trigger positive result on pregnancy test
Second period of prenatal development is the Embryonic Period
Gastrulation
Ectoderm
Outer layer that becomes hair, nails, & nervous system
Mesoderm
Middle layer, becomes muscle, bone, reproductive system, connective tissue, & circulatory system
Endoderm
Inside layer, becomes digestive tract and lungs
Neural Tube Closing
Lack of folic acid in mother can cause neural tube defects
Anencephaly, neural tube fails to close at top
Spina Bifida, neural tube fails to close at the bottom
Ectopic Pregnancy:
Implantation in an area other than the uterus
Early Miscarriage
Estimated of all zygotes that are formed from fertilization, 31% will make it to birth, germinal and embryonic periods most risky in terms of miscarriage, estimated 60% of all zygotes won't survive until implantation, of those that do implant 20% will not survive until end of embryonic period
Reasons for early miscarriage:
Errors in Mitosis
Few cells in germinal & embryonic periods, errors in cell division can be devastating to offspring since there are not enough healthy cells to compensate
Inheritance of Defective Set of Chromosomes
Some offspring will not survive with a genetic disorder
Implantation Errors:
Result in conceptus implanting in area other than uterine lining, will not sustain life and can be dangerous for mother, ectopic pregnancy, most commonly occurs in fallopian tubes
Hormonal Issues
Hormonal changes in mother at point of fertilization & throughout pregnancy sustains the pregnancy, if certain hormonal changes don’t occur early, it will not signal body to prepare for pregnancy, instead signals start of menses which ends pregnancy
Cesarean Sections
1/3 of U.S. births occur by cesarean section or “C-section”, World Health Organization has estimated cesarean sections medically indicted in only 15% of births, meaning that it is often recommended in more cases than necessary
Reasons for c-sections
Placental or umbilical cord problems
Baby is in distress
Issues with baby positioning in the uterus (breech position, feet down)
Incision is made in mother’s abdomen, and baby is delivered through incision
Recovery for mother is typically lengthy & demanding
Important vocab to note:
Lanugo, soft fine hair that covers the fetus
Meconium, fetal feces
Quickening, first fetal movements felt by the mother
Vernix caseosa, whitish coating on skin of fetus
Functions: Temperature regulation, act as lubricant during delivery, provides moisturizing properties, antimicrobial properties
Viability, offspring capable of living outside of the womb
Oxytocin, hormone that starts the labor process & allows fetus to prepare for delivery
Placenta, Disc-shaped structure that allows for exchange of nutrients, vitamins, oxygen and waste products between mother and offspring
Neurogenesis, development of new neurons
Neural migration, movement of neurons to proper locations in the nervous system
Cephalocaudal, pattern of growth that refers to idea that head and brain take precedence
Proximodistal, pattern of growth that refers to idea that spine and features closer to center of body take precedence
Amnion, bag that contains clear fluid in which developing embryo floats
Teratogens include any substance or agent that can cause a birth defect
Examples of factors that influence the level of severity of birth defects:
Dose
Greater level dose of a teratogen, more likely it is to cause birth defects & increases the risk of severity
Genetic Susceptibility
Genetics of both mother & offspring influence effect of teratogens
Time of Exposure
During prenatal development, body and brain structures tend to develop at certain time periods, “critical periods” Whatever developing at the time of exposure can be affected
Teratogen Exposures:
Smoking:
Exposure to nicotine prenatally increases the risk of preterm birth, low birth weight, respiratory problems, cardiovascular problems, miscarriage, and sudden infant death syndrome (SIDS
Placenta Previa, problem with location of placenta in uterus, on case of smoking placenta is low in uterus, covering the cervix, offspring smaller
Placental Abruption, Placenta detaches from uterine wall prior to birth, deprives oxygen & nutrients from offspring
Alcohol:
Alcohol was avoided during prenatal development, prevents symptoms of fetal alcohol syndrome
Symptoms:
Lowered IQ, learning disorders, attention problems, memory problems, impaired executive functioning
Low nasal bridge, short nose & flat midface, thin upper lip, micrognathia (small jaw), microcephaly (small forehead), epicanthal folds, short palpebral fissures, minor ear abnormalities
Radiation:
Builds up in areas of body close to uterus & can be passed to offspring, best to avoid, most sensitive time period is between gestational weeks 2 to 18, increases risk of cancer, miscarriage, slowed growth, abnormal brain development
Caffeine:
Consuming more than 200 milligrams of caffeine per day has been shown to increase the risk of miscarriage
Prescription & Non-prescription drugs
Parts of Europe marketed Thalidomide, a sleep aid, as being safe for pregnancy which seemed to reduce symptoms of morning sickness, made widely available over the counter, before effects could be discovered, caused deaths of over 2,000 babies and serious deformities of 10,000 children including malformed/missing limbs, bone & organ problems
Tylenol considered safe during pregnancy
Maternal Diseases:
Rubella:
“German Measles”, puts offspring at risk for cataracts, Cardiac issues, intellectual disability, brain damage, & deafness
Genital Herpes:
Transfer to offspring through infected birth canal & cause brain damage or death, C-section required
Syphilis:
Damaging later in pregnancy, offspring at risk for eye lesions, skin lesions, & blindness
Toxoplasmosis:
Exposed through exposure to cat feces or in soil, offspring at risk of brain damage, loss of vision, & intellectual disability
HIV/AIDS:
3 major ways HIV/AIDS transferred to offspring, during gestation (rarer), during delivery, through breastfeeding
Gestational Diabetes:
Requires treatment during pregnancy, risk of larger than normal birth weight & offspring risk of diabetes
Maternal Nutrition
Nutritional Recommendations
Folic Acid, 400 mcg., prevents neural tube defects
Iron, 27 milligrams, prevents pre-term birth & low birth weight
Iodine, 200 mcg, aids in development of brain & spinal cord
Vitamin D, 600 IU, aids in growth of bones & teeth
DHA, 200 milligrams, aids in development of brain & eyes
Calcium, 1,000 milligrams, Aids in growth of teeth, bones, muscles, hearth, & nervous system
Incompatible Blood Types
RH incompatibility, mother is RH negative, and offspring is RH positive
RH factor has to do with protein found on surface of red blood cells
If RH negative, protein is absent, RH positive protein is present
If mother RH negative & offspring positive, offspring's blood has something forgein to mother’s body & mother’s body will make antibodies to attack what’s perceived as forgein
Precautions such as a series of injections during pregnancy, serve as “vaccine”, untreated can cause anemia, jaundice, heart failure, brain damage, & still birth
Maternal Age
Age of 35+ and adolescents are at greater risk
Ages over 35 increased risks of genetic abnormalities & pregnancy related problems
Adolscents less likely to seek prenatal care, increase likelihood of nutritional issues & other problems
The First Few Minutes of Life:
When baby born, cry & breathe on own, with first few cries, stimulates newborn to breathe, fills lungs with oxygen, changes newborns skin from bluish to pinkish color
Sometime mucus removed from nose & throat of newborn to clear air passageways, research suggests may not be necessary for healthy babies & suggest wiping face, nose & mouth
Umbilical cord clamped & cut leaving umbilical stump on newborn, falls off with next week
If not need medical intervention, newborn placed on mother’s chest for skin to skin, warming baby’s body temperature & regulates heart rate & breathing, cloth hat placed on head for warmth, newborn initiates breastfeeding from this position
After this initial bonding, healthcare providers monitor the infant's vital signs and overall well-being to ensure a smooth transition into the new environment.