Prenatal development

Human Karyotype

46 chromosomes

Image of your chromosomes

Sperm and Ovum Karyotype (each)

23 chromosomes

Random placement of chromosomes in sperm and ovum cells

Are Sperm and Ovum replicas of Grandparents?

No - there are infinite combinations

How many times are traits/alleles coded?

Twice (each gene exists in pairs, one allele from bio mom, one allele from bio dad)

Genotype

Genetic code: genotype (what the chemical code is on the alleles)

Homozygous

Matching

- Both alleles code for the same thing

- Ex. Two alleles for curly hair

Heterozygous

An organism that has two different alleles for a trait

Phenotype

Manifestation of trait

- How the code manifests on the body

When:

Brown is dominant to red

Red is dominant to blonde

Blonde is recessive

Father has red hair (Genotype: Red Blonde)

Mother has brown hair (Genotype: Brown blonde)

1st grid: Brown hair girl, Brown Red Genotype

2nd grid: Brown hair male, Brown Blond Genotype

3rd grid: Red hair male, Blonde Red Genotype

4th grid: Blonde hair girl, Blonde Blonde Genotype

Sex-linked traits

- Y and X chromosomes

- Traits controlled by genes located on sex chromosomes

- Y -chromosome: all fathers pass to all sons

- X-chromosome: whatever is on it will be expressed in sons, whereas daughters need both if recessive

ex. Color blindness, baldness, heterophilia

--complex inheritance

Y-chromosomes

All fathers passed to all sons

X-chromosomes

Complex inheritance

Intersex

- Neither female nor male

- Starts as physical, then can be psychological

Are intersex individuals hermaphrodite?

No (we don't have individuals with both ovaries and testes)

How many intersex etiologies are there?

13+

What kind of intersex etiologies are there?

Genetic, prenatal and postnatal

Prevalence of non-binary individuals?

1 in 75

Not the same as intersex as being non binary tends to be psychological in its origin, Starts as mental, then can have a physical representation

Prevalence of individuals with ambiguous genitalia?

1 in 2000

External genitalia is not clearly a vulva or penis,it is a lot less frequent than someone who identifies as non binary. You can be intersex, even if you don't have ambiguous genitalia, according to some

Prevalence of individuals whose intersex conditions are physical and not psychological?

1 in 1500

This is one of the definitions of intersex

Genetic intersex

- Chromosomal

- Sex chromosomes

- Controversial

Turner's syndrome

- Xo (only one chromosome)

- Tend to be assigned female at birth

Turner's syndrome prevalence

1 in 2500 "female"

Turner's Syndrome Phenotypic Expressions

- Short

- Wider Neck

- Broad chest

- Don't experience puberty in a typical way

Turner's Syndrome: Secondary sex characteristics

- Menstruation (doesn't occur)

- Ovulation (doesn't occur)

- Breast development (tend to have low estrogen so have less breat development)

This is due to low estrogen

- Some people with Turner's syndrome may identify as women, some may as intersex

Klinefelter's syndrome

XXY (three chromosomes)

Klinefelter's syndrome prevalence

1 in 1000 "male" births

What are individuals with Klinefelter's syndrome assigned at birth?

Assigned male at birth

What are the features of Klinefelter's syndrome?

- Low sperm count

- Infertility

- Breast Development

- Body hair

- Fat distribution

- Depending on what the X and Y chromosomes do, there is a spectrum of phenotypes

- Genitalia can also be diverse

Congenital adrenal hyperplasia genotype

XX

- Congenital (from birth)

- They absorb and produce more testosterone

- Some develop as women but have more muscle

- May identify as transgender, women, queer women, non-binary, intersex etc

- Already absorbed more testosterone in the womb

- Have a spectrum of phenotypes

Congenital adrenal hyperplasia prevalence

1 in 10000

Androgen insensitivity syndrome genotype

XY

- Unable to respond to androgens

- Though genetically male, they develop female physical traits

- Lack of testosterone absorption

- Pointy chin

- Can't have babies

- Lots of internal testes

- Often have a vulva but no uterus

- Tend to be extremely femme, can't menstruate, don't have ovaries, often have internal testes

- Can also be a spectrum

- Prenatal because the onset is prenatally

- Postnatal would be if an individual had an accident to their genitalia

Androgen insensitivity syndrome prevalence

1 in 20000

Atypical development

Number of chromosomes

Inherited Alleles

Mutated Alleles

Number of chromosomes

- You can have a different number of sex chromosomes and still live

- XXX: does not lead to unusual characteristics

- XYY: super male/criminals - have extra testosterone, they were assumed to be more likely to be violent, this is untrue

- Down Syndrome: third chromosome on the 21st pair

-> More likely to have heart issues

- if you get a third chromosome on any other chromosome pair, it does not sustain life

- Triploidy: when they have three chromosomes everywhere

- Can have different numbers of sex chromosomes, and still live

- Due to errors during cell division, resulting in structural or numerical abnormalities

Inherited Alleles

Huntingtons, Tay-sach's, PKU, cystic fibrosis, sickle-cell anemia

Huntingtons

- Dominant: having one allele for Huntington's will make it express

- 100% fatal

- Symptoms don't show up until their 40s

- Usually dominant fatal diseases fall out of generations, but this one doesn't because it gives time to reproduce

- Rapid degeneration and decay of the brain tissue

- Can plan for this through genetic counselling

Tay-sachs

- 100% fatal

- Recessive: both parents have to be carriers (only 25%)

- Appears around 3 years old, tends to kill by then

- A baby is born healthy and develops fine but their condition gets worse at the age of 3

- Tends to run in irish and jewish people

Genetic counselling is important because you can do IVF

- Screen the embryos and can implant the right embro (so we can avoid)

PKU

- Not fatal

- Recessive

- Both parents have to be carriers, only 25% chance

- If it's caught early, it can be avoided with proper diet at birth

- Body can't break down and digest amino acids, it becomes poison and causes brain damage

-> Usually in meat, cheese and beans

- At every Canadian public hospitals, infants are screened for PKU and can be put on an alternative diet and have a pretty typical lifestyle

Cystic fibrosis

- Mucus builds up in the digestive and respiratory tract -> causes respiratory congestion

- Constantly get pneumonia

- Recessive

- A lot of progress in terms of life expectancy for these individuals through medical science

Sickle cell anemia

- Co-dominant (something expressed in a non blended way)

- Have some blood cells that are round, but some that are crescent and moon shaped that hurt

- The crescent moon shaped blood cells hurt -> causes chronic pain

- Prevalence higher in black individuals because of high malaria counts

- The sickle cell can't carry the malaria disease because of the shape

Mutated alleles

- No family history, but one family member has different phenotype/genotype than their family due to mutation

Ex. albinism (spontaneously happens all through the animal kingdom)

What does pregnancy consist of?

1. Conception

2. Zygote formation

3. Embryo formation

4. Fetus implantation

5. Healthcare

When is the zygote and embroyo formed?

First trimester (trimister is relevant to the parent but not the offspring)

When does the fetus develop?

During the second and third trimester

Gestational Age

38 weeks

How many weeks does pregnancy last for the parent?

40 weeks

Conception to birth day cycle

28 day cycle

What day is the egg released?

Day 9-16

How long does the egg live?

24-48 hours

Conception

Tend to say we are pregnant from when we last had menstruation

Sperm meets the egg

25% implantation and pregnancy

75% chemical pregnancy (spontaneous miscarriage, chemically you were pregnant but your body and you didn't know it)

Out of those 25%, 15% will miscarry and probability increases with age

Fertilization

- Takes place in the fallopian tube

- 24-30 hours: chromosomes combine

- 36 hours: zygote divides into 2 cells

- 48 hours: 4 cells

- 3 days: 16-32 cells

- 4 days: Blastocyst of 100 cells - A ball of unspecialised cells

Main purpose of period of zygote: to multiply cells

If zygote embeds in fallopian tube: fatal to parent, symptoms: severe cramping in first two weeks- ectopic pregnancy

Implantation

- 5 days: zygote enters uterus

- 6-7 days: attaches to uterine wall

- 12-14 days: implanted on uterine wall

Implantation is complete (can get a pos on pregnancy test)

Connects with blood vessels

Signals parent's brain

Triggers hormones

Physiological reactions

Germ Disc

- Component of blastocyst sphere (the full blastocyst won't become the offspring, some will become placenta, etc → support for growth)

- Potential to turn into embryo

Gastrulation

Germ Disc

3 layers of cells

Ectoderm: outer layer: becomes skin, hair, peripheral nervous system

Mesoderm: middle later: becomes muscles and subcutaneous fat

Endoderm: inner layer: becomes the central nervous system (brain and spinal column), and digestive tract

- Specialization occurs at the start of the period of the embryo through gastrulation

- Gastrulation: When three layers pinch together

Week 3

- 3 weeks gestational age

- Can see the neural tube

- We're a neural tube at this point and it's incomplete

- Folic acid allows the neural tube to close

- Should go on folic acid as soon as you know you're pregnant

- Gap on the lower tube could lead to spina bifida and paralysis

- Gap at the top of the neural tube will lead to miscarriage

- Vestigial structure: tails and gills (no functional purpose, due to evolution)

- Size of a sesame seed

Week 4

- Organ & Limbs

- Start to see the buds of limbs

- Couple cells start to specialize to star organs, but the organs aren't functioning yet

- Eyes

-> Type of organ

-> Some photoreceptive cells - not elaborate yet

- Limb starts at the torso and then grows out

- Eyes are a couple of photoreceptive cells

Week 5

Kidneys

- Cells that become kidneys become more advanced

- Kidneys come earlier because we use urinary tract in the womb

Mouth and Tongue

- No lips -> primitive looking hole

Week 6

- Looks more human

- Face "details"

- Tail is shed

- Mature face

- No elbow or knees

- Lips

- Nose

- Eyelids

- Shed tail

- Limbs get longer

- Don't yet have elbows or knees

Week 7

- Neurogenesis -> first brain cells, growth of neurons, neurons develop

- Start of a few cells

- Brain and Nervous System

- Nerve cells are disorganized -> unsure if they feel pain

Week 8

- Head is much bigger

- Size of acorn

- Knees

- Ankles

- Elbows

3rd Month

- All human embryos are default female

- Looks feminine up to this point

Sexual development

- Release of testosterone

- Change ovaries to testes

- Vaginal structure to penis

-> Change ovaries to testes

-> Have to transition to male if enough tesoterone

-> This is when the change to male does not happen for some intersex people

- Twins: boy twin has to slow down here (takes like a month), slows down in all maturation... and girl twin keeps going so girl twin ends up coming out bigger and more mature

- Premie (and non premie) boys are more likely to develop health issues... this is also why boys tend to be slower developmentally (well into age 5-6) due to the exhaustive process of growing a penis - some scholars believe that this difference has lifelong implications

4th Month

- Feel movement (Kicks - indication in the past that miscarriage is likely not to happen)

- Quickening

- Strong enough to make waves

5th Month

- Lanugo - hair all over body, peach fuzz

-> Purpose: to help keep us warm because fetus doesn't have good cardiovascular functioning, which helps keep us warm

- Vernix - waxy, cheese like coating

-> Makes us more waterproof - helps keep us from being pruny (like when fingers get all weird when in water for long time)

6th Month

Neurogenesis Milestone

- Most neurons are created (but can still create more during life)

- Taste preferences

-> Amniotic sac can taste like certain things based on what parent eats

- Preference for rhymes & voices

- Sensitive to light

-> Don't think they can see colors yet

- Nervous system is functioning

- Hypersensitive to mother's voice

- Can respond to light

- Current cut off for Canadian legal abortions

7th Month

- Can breathe with assistance in incubator

- Age of viability (as early as 22 weeks)

-> Advanced lung development

-> Brain specialization

-> Body temperature regulation

8th Month

- Lunago sheds (peach fuzz sheds) because of body fat

- If baby born before this then they may still have the lunago

- Body fat increase

9th Month

- Position for birth

- Best position -> head down, back out

- Brain Specialization

Birth

- Baby moves to cervix

- Hormone trigger uterine muscles

- Amniotic fluid pushed against cervix

- Cervix will enlarge

- Sometimes amniotic sac may rupture, but not always

- Cervix will start to dilate (get bigger)

- Parents can't trigger labour

- Hormones are triggered when babies push against the cervix, causing labour since the uterus contracts

Labour Stage 1 - Early Labour (Pre-labour)

- Labour is not painful

- No need to push

- 10-16 hours (less for 2nd child)

- Contractions weak and irregular

- Cervix 5cm dilated

- Braxton hicks only contract on side of uterus, actual contractions are on top of the uterus

- Efacement: vaginal canal shorter

Labour Stage 1 - Active Labour

- Lasts 2-8 hours

- Contractions very strong and regular, start to hurt

- Cervix 7-8 cm dilated

Labour Stage 1 - Transition

- Post painful part

- When infant head has to overpass parent's pelvic bones → want baby to be head down back out bc don't want baby's knob on head to hit pelvic because it's painful

- Contractions extreme and constant

- Cervix 10cm dilated

Labour Stage 2

- Start pushing (when baby's head is past pelvic bone)

- Baby moves down birth canal

- Crowning (can see baby's head past the cervix and it's moving past the birth canal)

- Baby is born

Labour Stage 3

Afterbirth

- 10-15 minutes

- Placenta

- Detach from the uterine wall and leave mom's body

- Can cause toxic shock in the mom if it's not out

- Other support structures

- Tends not to have pain

- Nursing causes uterine contractions, so nursing the baby can help get placenta out

Complications

- Induction

-> Pitocin (artificial oxytocin)/Oxytocin

-> Oxytocin makes muscles contract

-> Pitocin makes the uterus contract, can medically induce labour

- Irregular position

-> Can massage the baby to coax them into the right position, but doesn't always work

- Breech position

- Cephalopelvic disproportion

-> Caphal: head, pelvic: pelvis

->Head to pelvic ratio is not enough to get the baby through the vaginal canal

-> Often happens with petite mom and large baby

-> c-section is needed

- Preeclampsia

-> most fatal for pregnant mothers (highest cause of maternal death)

-> Has to do with proteins in the placenta that causes elevated blood pressure and enlargement of the heart and may cause a heart attack

- Prolapsed umbilical cord

-> Umbilical cord gets around neonate's neck, so they can't breathe

-> Umbilical cord can get pinched

-> May be c-section, or use other techniques

Cesarean Section

- Incision made in abdomen

- Increased bleeding

- Risk of infection

- Little risk for babies

-> survivability rate is high

- Over recommended

-> Often recommended for subsequent c-sections

- Mothers need extra rest

Pain Management

Nitrous oxide -> Helps with anxiety, not pain, calms the nerves (pain may lessen as a result), laughing gas, use this only when contractions are happening

Narcotics -> controversial since it can affect the baby, can only be done in stage 1 active, can slow the baby's heart rate, make them sleepy during the birthing process and we want them to be alert ex. demerol or fentanyl

Epidural -> needle injects into spinal column, paralyzes and makes you numb completely down, don't impact the baby, correlated with more c-sections since due to not being able to feel anything, it makes it harder to push

Prenatal Health Care

- Personal history

- Blood pressure

-> Due to preeclampsia

- Dental records

-> Have to do before pregnancy - painful to do while pregnant

-> Tooth infection can lead to miscarriage

- Urinary & blood

-> Want to see HCG levels double every 48 hours

- Ultrasound

-> First trimester ultrasound, one later on to see anatomy, one at end to see position

- Pelvic exam

- Uterus measurements

-> Take a measuring tape and measure from pubis bone to fondis (top part of uterus) → the amount of centimeters is the amount of weeks on average

Genetic Screening

- Genetic counselling

-> Less common

- In vitro Fertilization

- Amniocentesis

-> Done at 8 weeks gestational

-> Needle through vaginal canal and draw a bit of amniotic fluid to run a DNA test... this increases the risk of miscarriage because may rupture amniotic sac at week 10

-> Used to see if there's a genetic disorder

- Chorionic Villus Sampling

-> Week 14, done by sampling the placenta to run DNA test

-> Used to see if there's a genetic disorder

- Newborn Screening

-> Heel prick test

-> Most common

Teratogens

- Agents, such as chemicals and viruses, that can reach the embryo or fetus during prenatal development and cause harm

- Not worried about teratogens influencing the zygote because their blood vessels aren't connected to the mom's blood vessels → before you get positive on the pregnancy test, the baby is not affected

- Dangerous influences

- Genotype

-> Some people are genetically more sensitive to teratogens

- Dosage

- Critical Periods

-> Critical periods of development

-> Eg: The critical period of arm development will be affected by teratogens then

Diseases

- HIV

-> Transmission of HIV from the biological mother to infant; antiviral treatment during prenatal period drastically reduces transmission to less than 5 percent

-> Herpes - have to do C-section because if vaginal birth then baby could get cold sores on face

- Syphilis

-> can lead to miscarriage

-> Can have severe implications on embryo

-> can be treated with antibiotics

-> Premature birth, low birth weight, and fetal death; congenital diseases

- Zika

-> From mosquitos - linked to a small head (microcephaly) - have to wait nine months after travelling somewhere with mosquitos

-> Microcephaly, hearing and vision loss, and intellectual disability

- Toxoplasmosis

-> Mom is asymtomatic

-> Bacteria that lives in cat and sometimes rabbit poop

-> Linked with miscarriage

- Salmonella

-> Food-borne

-> Can be asymptomatic, but cause miscarriage

- Listeria

-> Food-borne

-> Can be asymptomatic, but cause miscarriage

Recreational drugs - alcohol

Damage to developing organs; fetal alcohol spectrum disorder (FASD)

Recreational drugs - Nicotine

- Low birth weight, smaller baby, premature birth, stillbirth

- If you smoke something that isn't oxygen, you are starving the baby of oxygen and baby can't grow without oxygen, may come early because don't have adequate respiratory supply

- Linked to allergies and asthma

- Don't know if it's the nicotine itself or just the smoking part

Recreational drugs - cannabis

- Decreased growth; deficits in attention and long-term executive functions; increased impulsivity

- Harder to measure

- Heavy use is linked with hyperactivity and learning disability

Recreational drugs - caffeine

- Safe level of caffeine - 200mg a day

- Increasing embryos heart rate, so they may not grow the best

- Withdrawal after born, higher heart rate, smaller size

Medicinal drugs - Thalidomide

- Very short or missing arms and legs and other congenital birth defects when taken during early pregnancy

- Drugs prescribed to help with morning sickness, but is toxic to babies -> stops limb development, inhibits growth of arms and legs

Medicinal drugs - Aspirin

- Miscarriage if high doses are taken early in pregnancy; increased risk of bleeding if low doses are taken

- Causes miscarriages because it's a blood thinner

- Not Tylenol or advil

Medicinal drugs - Certain antidepressant medications

- Risk is not clear

- Everyone is different but some aren't good for fetal development

Other medicinal drugs

Sedatives (anything that makes you sleepy, the baby may OD on sedatives, eg: anxiety pills), Herbal remedies (Not well regulated, so much do research before taking supplements)

Chemicals

- Pesticides

- Cleaning spray

- Industrial Chemicals

- Heavy metals

-> Lead

-> Mercury

-> Though the placenta tries to filter these out, it doesn't do a great job... ex. Tuna has mercury

Chemicals - Lead

Increased risk for miscarriage, preterm birth, and low birth weight; damage to brain,kidneys, nervous system; learning or behavior problems

Chemical - Mercury

Brain damage and hearing and vision problems

Hazards

Radiation, heat, injury

Hazards - Radiation

- Organ anomalies, slowed growth, or nervous system abnormalities depending on exposure timing

- Sun, tanning beds, hottubs, heating pads

Lifestyle

- Age

-> If you have a baby too young, your hips will be disproportionate since hips are often underdeveloped

-> People can have healthy pregnancies into their 40's if they freeze their eggs

-> Once over 40, chromosomal abnormalities start to climb

- Exercise

-> No contact sports

-> Balance becomes compromised later on in pregnancy

-> Fetus can shift without telling your nervous system

- Sleep and rest

-> Lowers cortisol level, increases oxygen supply

-> Stress is as problematic to an embryo as cigarettes - deplete oxygen to embryo just as much as cigarettes

- Hydration

- Nutrition

-> Folic acid, lean protein, antioxidants, fibre

- Iron: hurts the parents, baby will steal mom's iron (may need iron blood transfusions or supplements for mom)

Apgar Scale

- First assessment done after birth

- 10 is the highest scale, below 3 is stillbirth, 0 is an emergency

Apgar Scale: Appearance

- Rosy appearance is good, blue appearance is not good

- Blue feet often means circulatory systems hasn't kicked in yet

- Can cause loss of black babies because some people aren't trained to recognize blue feet for them

Apgar Scale: Pulse

- Good heart rate, wanna see a fast pulse

- Irregular or slow = 1

- No pulse = 0 = emergency

Apgar Scale: Grimace

- Crying; good natural response

- Measures reflex irritability

- A cry

- A baby who comes out alert and crying = 2= good

- If no crying, or vocalizing but have a smirk/responsive = 1 »»no response = 0

Apgar Scale: Activity

- Movement of limbs

- Measures muscle tone

- Want to see them moving their limbs

- Low level activity = 1

- Ragdoll = 0

Apgar Scale: Respiration

- Breathing

- Expect normal breathing to be pretty fast = 2

- Slow breathing = 1

- No breathing = 0 = start CPR

- 0= emergency, 7-10=-3 pretty good, under 3= still birth