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Prenancy timelines (2 of them)? Clinically used one?
266 days (fertilization) or 280 days (LNMP) which is clinically used
What occurs during each trimester?
1 trimester (0-3 months; 0-12 weeks after LNMP): all major systems develop
2 trimester (4-6 months; 13-28 weeks after LNMP): fetus grows sufficiently in size; US can be used to visualize
3 trimester (7-9 months; 29-40 weeks after LNMP): fetus can live if born prematurely; weight determines maturity
What tool can be used to determine size, predict expected delivery date, and probable age of fetus?
The most critical period in development is?
when cell division, differentiation and morphogenesis are at their peak
Rank the following in terms of what grows earliest.
- Earliest to Latest
- CNS & Heart
- Brain (critical from 3-16 weeks)
- External genitalia (in later weeks)
The period from 0-8 weeks after conception is called?
What organs develop during this time?
- Embryonic period
- development of all major organ systems
Which period in pre-natal life is most sensitive to abnormal developement?
Fertilization, bi-laminar disc (epiblast/hypoblast), implantation in endometrium
Appearance of primitive streak, gastrulation and differentiation of three germ layers, neuralation (notochord development), heart and embryonic blood vessels form. Cardiovascular system development is correlated with urgent need for blood vessels to bring O2 and nourish embryo
Neural tube formation, neuropores close, folding of embryo, pharyngeal archs appear, heart produces ventral prominence to pump blood, upper limb buds form (before lower limbs), otic pits (interal ear) and lens placodes (future eyes) are visible
Growth of brain (and head), mesonephric ridges indicate site of mesonephric kidneys (interim kidneys)
*Ultrasound can be done now
elbows, handplates, digital rays (future fingers), lower limbs (4-5 days after upper limbs), embyo movement,
intestines move to extraembryonic coelom to accompany rapidly growing intestines (umbilical herniation)
Limbs undergo considerable changes (future digits more noticeable from notches), ossification of bones in upper limb,
Digits of hand and feet seperate
Purposeful movement of limbs
embryo has distinct human characteristics, but head abnormally large
Name of week 9 to birth?
What is special about this period?
How can the growth of this embryo be measured?
- Fetal period
- proliferation, differentiation, increase in size
- crown-rump length (head to butt), or crown-heel length
Weeks 9-12 (month 3)?
- CRL > CHL (i.e. the head to butt region grows more)
- 11th week - Intestines return to abdomen
- early on the liver used to be major site of erythropoiesis, but now that process starts in spleen
- urine is produced
- gender can be distinguished at 12 weeks
Weeks 13-16 (Month 4)?
- Bones visible on Ultrasound
- Fetal ovaries differentiated and contain oogonia
Weeks 17-20 (Month 5)?
Fetal movements (quickening)
Fetal skin covered with vernix caseosa
(mix of dead epidermal cells and fatty secretions) to protect skin from exposure to amniotic fluid
- Eyebrows, head hair, and lanugo (fine downy hair covering fetus) are visible
- Uterus and vagina form
- testes descend (but still in abdominal wall) as are the ovaries
Weeks 21-26 (month 6)?
- Weight gain
- surfactant secreted
**fetus can technically live outside womb but may die from respiratory failure since it is immature
Weeks 26-29 (Month 7)?
- Fetus can survive if given intensive care
- lungs and pulmonary vasculature are developed
- the CNS has matured to a stage where it can direct breathing
- bone marrow is major site of erythropoiesis
Weeks 30-34 (month 8)?
- skin is pink
- fetuses 32 weeks and older usually survive is born prematurely
Weeks 35-38 (Month 9)?
- nervous system is sufficiently mature to carry out integrative fxns
- Testes are in scrotum
**undescended testes (cryptorchidism)
1. morphological defect (inherited i.e. chromosomal abnormality)
2. morpological defect NOT inherited (fetal alcohol syndrome)
3. abnormal form from mechanical forces (i.e. not enough amniotic fluid)
Syndrome vs. Association?
Syndrome: group of anomalies that have common cause (down syndrome)
association: nonrandom appearance of multiple anomalies that occur together more freq. than by chance..cause has not been determined (i.e. VACTERL - veterbral, anal, cardiac, tracheoesophageal, renal, limb anomalies)
Most of congenital anomalies are environmental, genetic, multifactorial, unknown?
agent that can produce congenital anomaly
At what time during embryonic period does this mess you up?
- causes meromelia (missing part of limbs) , amelia (missing limb) , or micromelia (small limbs)
- 24-36 days (1 month) after fertilizationcontraindicated in pregnant women
Retinoic Acid problem?
Critical period to NOT take it?
Isoretinoin (acutane) shouldnt be taken 1 month after fertilization or causes craniofacial dysmorphism, cleft palate, cardiovascular anomalies, NT defect, mental retardation
iPledge = mandatory distribution program intended to prevent drug use during pregnancy
Fetal alcohol syndrome?
- maternal consumption of alcohol
- mental retardation, microcephaly (small head), short palpebral fissures (short eyelid), epicanthal folds, maxillary hypoplasia (upper jaw), short nose, thin upper lip, abnormal palmar creases, joint anomalies, congenital heart diseases
caused by excessive cell death in neural crest cells
Cig. smoking causes intrauterine growth restriction.
what are more common as a result of cig. smoking?
what does nicotine do?
chronic fetal hypoxia?
- 1. premature delivery (twice as freq.), low birth weight
- 2. decrease blood flow to fetus
- 3. low oxygen levels
Rubella virus causes what?
sensorineural hearing loss, eye defects (glaucoma), and cardiac defects
**Can cross placenta
- most common infection of fetus, majority are asymp. fetus, 10% of symptomatic fetus present:
- jaundice, hepatosplenomegaly (large liver/spleen), petechial rash, microcephaly (small head), motor disability...
Toxoplasmosis is caused by what?
- Caused by parasite
- symptoms: chorioretinitis, hydrocephaly (build up of CSF in head), intracranial calcifications (Ca2+ deposits in brain)
most fetus asymp. but can develop visual impairment, hearing loss later
Folic acid helps what?
If you have a family history what dose?
No family history what dose?
- neural tube closure
- 4.0 mg FA (prior to and during preg.)
- 0.4 mg FA (3 months b4 conception)
Spina bifida occulta?
spinda bifida cystica (meningocele, meningomyelocele)?
small seperation of gap in one or more spinal vertebrae
cyst-like protrustion in vertebral arch (only meninges are exposed in cyst-like sac, meninges and spinal cord and or nerve roots are exposed in cyst-like sac)
sac-like protrusions of brain and meninges through opening in skull
absence of a major portion of brain
X-rays in preg. women can cause what?
microcephaly, spina bifida, cleft palate, limb defects, CNS anomalies
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