WI- Conception and Fetal Development

first day of the last menstrual period

What is consider the last menstrual period?

When used correctly most reliable estimator of gestational age

Why is the last menstrual period important?

lunar month, 10 specifically/ 40 weeks

How do clinicians measure pregnancy gestation and how long is pregnancy?

Fertilization and Implantation

Placenta Development

-Placenta

-Fetal Membranes

-Chorionic Villi

-Umbilical Cord

-Amniotic Fluid

What are the components of the pre embryonic stage?

Fertilization

sperm and ovum unite at conception to form a zygote

12- 24 hours

How long does an ova fertile last?

72 hours

How long does a sperm fertile last?

around day 6-7

At what day does blastocyst attach to uterine wall and trophoblast cells develop outside of blastocyst?

Day 11-12m

At what day does the embryo implant and placenta begin to form?

produce hormones(hCG, progesterone, estrogens, hPL, Relaxin, Inhibin)

Metabolic functions(respiration, nutrition, excretion, and storage)

What is the placenta function?

15 to 20 segments called cotyledons

What is the placenta made up of?

Maternal portion of placenta

• After implantation, the endometrium is called the decidua

• Red, flesh-like surface

• Fetal Membrane: Chorion

Fetal portion of placenta

• Covered by amnion (fetal membrane)

• Shiny, gray

Chorion and Amnion

What are the two fetal membranes?

Chorion

• Outside; toward uterus

• Develops from trophoblast

• Contains chorionic villi (next slide) on the surface

• Becomes the covering of fetal side of the placenta

• Contains major umbilical blood vessels

Amnion

• Inner cell membrane develops from interior cells of the blastocyst

• Becomes covering of the umbilical cord

• Covers chorion of the fetal surface of the placenta

Chorionic Villi

fingerlike projections that extend into endometrium

-Obtains O2 and nutrients from maternal blood

-Dispose of CO2 and waste products into maternal blood

no; fetal needs are met through diffusion

Do Chronic Villi and maternal vessels communicate directly?

Wharton’s jelly

a specialized stretchy connective tissue that prevents compression of umbilical cord in utero

2 Arteries and 1 Vein

How many veins and arteries are involved with the umbilical cord?

embryonic

What portion of the placenta does the umbilical cord fuse with?

provides circulatory pathway from chronionlc villi to embryo

What does the umbilical cord do?

waste from fetus to mom; small

What is the function of the arteries in the umbilical cord?

O2 and nutrients from mom into fetus; large

What is the function of the veins in the umbilical cord?

Amniotic Fluid

• First gets fluid from diffusion from maternal blood

• Amount ↑ as pregnancy progresses

• Fetus swallows fluid; Fluid flows in/out of fetal lungs

• Fetus urinates into fluid => ↑ Volume

Fluid

• Maintains temperature

• Source of oral fluid

• Repository for waste

• Protects fetus from trauma

• Allows for freedom of movement assisting

musculoskeletal development and growth

Oligohydramnnios

les than 400 mL of amniotic fluid

Polyhydramnios

Greater than 2000 mL of amniotic fluid

from day 15 to 8 weeks post conception

How long does the embryonic period last?

the embryonic period

What is the most critical time in the development of organ systems and main external features?

Teratogen

agent that acts directly on the developing fetus, causing abnormal embryonic or fetal development

viruses, bacteria, heavy metals, medications, chemicals, radiations, etc.

What are examples of teratogens?

birth person and fetal genotype

stage of development when exposure occurs

dose and duration of exposure of the agent

What does the effects of teratogen depend on?

malformations of the heart, limbs, eyes, and other organ systems as early as 3 weeks post conception

What are the types of outcomes with teratogens?

alcohol, cocaine, lithium, valproic acid

What are the four major chemical teratogens?

growth restriction,cognitive impairment, microcephaly, various malformations of face and trunk

What are the effects of alcohol?

cardiac and central nervous system anomalies, growth restriction

What are the effects of cocaine?

heart anomalies

What are the effects of lithium?

neural tube defects

What are the effects of valproic acid?

TORCH

Microorganisms associated with known congenital disease

T- toxoplasmosis gondii

O(other)- Listeria, Treponema pallidum, varicella zoster virus, enteroviruses, and parvovirus B19

R- Rubella

C- Cytomegalovirus

H- herpes simplex virus-1 and 2

What does TORCH stand for?

Toxoplasmosis

parasite that invades tissues and damages fetal brain

Toxoplasmosis S/S

Fever, fatigue, headaches, swollen, lymph glands, muscle aches/pains

Rubella birth defects

deafness

cataracts

heart defects

intellectual disabilities

liver and spleen damage

low birth weight

skin rash at birth

risk of miscarriage or stillbirth

cause of autism

What could rubella lead to?

False

True or False: Pregnant women should get the MMR vaccine

greater than 1:8- Immunity

less than 1:8- Susceptible

Rubella Dx

1 month

How long should a women wait after the MMR vaccine to get pregnant?

Cytomegalovirus

member of herpes family

Chronic infection – 50% of people have antibodies to CMV

• The most common perinatal infectious agent (1% live births)

• Close contact - CMV passed through body fluids (saliva, urine, blood, vaginal secretions, semen)

Cytomegalovirus S/S

fever, sore throat, fatigue, swollen glands(mild

Cytomegalovirus Prevention

hygiene, especially hands; no sharing of utensils

Congenital CMV

• 1:200 babies born with congenital CMV

• Infant Mortality Rate: 3-10% in infants w/symptomatic CMV

• 1:5 babies with congenital CMV will be sick or have long-term health problems

hearing loss, developmental & motor delay, vision loss, microcephaly, seizures

What are the long term effects of CMV?

Herpes Simplex Virus

viral infections causing painful, recurrent lesions- oral and genital

Neonatal HSV

• Incidence: 1 in 2000 live births in U.S.

• Transmission: 85% intrapartum; also ascending infection, postnatal contact

• may be localized to skin, eyes, mouth, CNS, or disseminated

• Encephalitis and disseminated disease have a high mortality rate =>Neurologic sequelae common among survivors

HSV Prevention/ Treatment

• Pts w/active genital ____ infection given antiviral

therapy beginning Week 36

• Acyclovir 400 mg or Valacyclovir 500 mg

• Culture & Sensitivity (C/S) recommended in active ___

infection at term and with prodrome symptoms

• Avoid acquiring during pregnancy (3rd trimester greatest risk)

Congenital Syphilis

Transmitted via placenta during pregnancy or contact w/maternal

lesions post-birth

Congenital Syphilis risk factors

late/no prenatal care, inadequate maternal screening, HIV

Congenital Syphilis risk to fetus/ newborn

untreated maternal syphilis- 40% chance of miscarriage, stillbirth, or death

hepatosplenomegaly, copious nasal secretions (snuffles- very infectious, lymphadenopathy, mucocutaneois lesions(very infections), pneumonia, osteochondritis and pseudoparalysis, edema, rash, hemolytic anemia, thrombocytopenia

What are the clinical manifestations around 1-2 months?

CNS, bones and joints, teeth, eyes, and skin

What are clinical manifestation if not treated at birth?

Cogenital Syphilis Goal

• Prenatal testing & treatment early and close to birth

• Prompt treatment usually prevents fetal infection

• Delay can lead to various fetal issues)

• Should be performed during 1st prenatal visit

• Immediate testing for people with no prenatal care

9 weeks gestation to birth

How long does the fetal stage last?

Viability

ability of the fetus to survive outside the uterus which is typically with the help of medical interventions

22 weeks

What is the earliest a baby can be safely born?

cardiovascular system

What is the first system to function during development?

1. Ductus Venosus

2. Foramen Ovale

3. Ductus Arteriosus

What are the three shunts?

Allow the Blood to bypass the Fetal Liver and Lungs

What is the purpose of the 3 shunts?

increase O2 blood from placenta goes to umbilical vein

1st step of oxygenated blood from placenta to fetus

O2 blood to nonfunctioning liver

2nd step of oxygenated blood from placenta to fetus

Most O2 blood bypasses liver through ductus venosus

3rd step of oxygenated blood from placenta to fetus

Increased O2 blood to Inferior Vena Cava

4th step of oxygenated blood from placenta to fetus

Increased O2 blood to right atrium(bypasses Right Ventricle and lungs) through foramen ovale to the left atrium (LA) (increased pressure in the fetal lungs make blood flow easily from RA to LA)

5th step of oxygenated blood from placenta to fetus

Increased O2 blood to left ventricle

6th step of oxygenated blood from placenta to fetus

Increased O2 blood to aorta

7th step of oxygenated blood from placenta to fetus

Increased O2 blood to body

8th step of oxygenated blood from placenta to fetus

IVC and SVC also have deoxygenated blood that goes to right side of heart to be cleared by parent

1st step of deoxygenated blood from fetus to placenta

Blood foes to Right Atrium— Right Ventricle— pulmonary artery avoids lungs by going from the ductus arteriosus to aorta— to descending aorta to umbilical arteries

2nd step of deoxygenated blood from fetus to placenta

to placenta to be cleared by Parent

3rd step of deoxygenated blood from fetus to placenta

begins in embryonic life and continues into childhood

When does the respiratory system finish development?

pulmonary surfactants

used to determine degree of fetal lung maturity— ability of lungs to function after birth

Ex- Lecithin and Sphingomyelin

Lecithin

most critical surfactant required for postnatal lung expansion

Sphingomyelin

remains constant in amount

2:1- 35 weeks gestation

What is the L/S ratio that is considered mature?

Respiratory Distress Syndrome(RDS)

due to insufficient surfactant— alveoli collapse— decrease gas exchange— hypoxemia

RDS S/S

grunting sound, increase respiratory rate (RR), retract their muscles trying to inhale and get oxygen

during the 6th week

When does hematopoiesis begin in fetal liver?

Around Week 24

When does Bone marrow over for the fetal liver?

after 6 weeks

When do antigenic factors( blood type and Rh factors) present?

around week 4-5

When does the hepatic system develop?

Week 12

When does bile begin to form?

umbilical vein

Where does the liver get its blood supply from?

Bilirubin

brownish yellow substance found in bile and is produced when liver breaks down old RBC

main route

Fill in the blank: Placenta is _____ ______ for bilirubin elimination

Foregut

forms the esophagus, stomach, and duodenum(5- 6th week)

Midgut

becomes the small intestine and part of the large intestine

Hindgut

gives rise to the colon and rectum

helps digestive system mature and contributes to development of lungs (fluid moves in/ out of airways)

What is the purpose of fetus swallowing amniotic fluid?

Meconium

waste products (swalllowed AF, mucus, bile, dead cells) collect in intestines as dark green/ black ________

Week 5- not fully functional until after birth

When do kidneys form?