Unit 2: 12 + 13

when is implantation

6-10 days after conception

how long does pregnancy last

40 wks or 280 days

what is the critical period

day 15 - week 8

at the end of 8 weeks

baby looks human and organ systems and external structures are present

teratogens

any substance that causes abnormal development

• most harmful during the critical period

the three germ layer

by 4 weeks, the ectoderm, mesoderm and endoderm from

ectoderm

outer most layer, from nervous system and skin

mesoderm

middle layer, form;

• muscle, cartilage ad skeletal

• kidneys

• reproductive system

• cardiovascular system

when do cardiac anomalies happen

3-5 weeks

endoderm

middle layer, forms:

• endocrine gland

• respiratory system,

• GI tract

• liver and pancreas

when is the fetal heart beating

5 weeks , it is the first system to develop

ovum period

conception - 14 days

embryo period

15 days - 8 weeks

fetal period

9 weeks and beyond

chorion

• outer membrane of the amniotic sac

• becomes fetal side of the placenta

• has major umbilical vessels that branch to the placenta

amnion

• inner membrane of the amniotic sac

• becomes the covering of the umbilical cord

• as fetus grows, amnion gets bigger to accommodate baby

amniotic fluid

• 98-99% water

• increases weakly

what volume should the amniotic fluid be

• by 8 wks 10ml

• by 15 wks 250 ml

• at 32 weeks it stabilizes at 800 mL

oligohydraminos

• less than 300mL and 32 weeks or more

• indicates fetal renal impairment

polyhydraminos

• over 2 liters @ 32 weeks or more

• indicates GI

functions of amniotic fluid

• thermoregulation for baby

• fluid/electrolyte homeostasis

• oral fluid and storage for waste

• musculoskeletal development - freedom of movement

• contains immunoglobulins and has antibacterial factors

• keep baby untangled with umbilical cord and amniotic bands

yolk sac

• cavity on the other side of the developing embryonic disc

• transfers maternal nutrients and oxygen for the first 5-6 weeks

umbilical cord

• 2 arteries that carry deoxygenated blood from baby back to placenta

• 1 vein that carries oxygenated blood to baby

• 40-70cm @ term

• knots can prevent perfusion

Whartons jelly

• gel in cord to keep it patent and prevent compression

placenta uses

• all waste products and CO2 are sent back to maternal blood via placenta

• O2 and other nutrients sent to baby via placenta

• acts as our fetus’s lungs

• also stores nutrients baby needs

placenta growth

• begins forming @ implantation, complete by week 12, grows until 20 weeks\

• covers ½ of uterine wall by 20 weeks

maternal-placenta embryonic circulation is in place by ?

day 17 - also when baby’s heart beats, but we cannot hear it yet

Placenta hormones

• HCG

• Progesterone

• hCS

• progesterone

HCG

• detected in 8-10 days in maternal blood

• max levels at 60-70 days then drops

• signals ovaries to keep progesterone high which keeps our uterine lining from shedding and nutrient rich

progesterone

• decreases contractility of smooth muscle (including uterus)

• maintains endometrium

• stimulate maternal metabolism

• stimulates development of brats alveoli

women who lack progesterone …

are unable to keep a pregnancy bc the uterus will contract without it causing miscarriages and pre-term labor

• can be given PO or vaginally

Estriol

• form of estrogen

• produced by placenta at wk 7

• measured to determine placenta function

• increases by the end of pregnancy

what maternal factors can affect placental perfusion

• hypertension

• hypotension

• low cardiac output

• hemorrhage

• cocaine

• teratogens

viability

capability of fetus to survive outside the uterus

fetal hemoglobin

• has a much higher affinity for O2

• carries 20-30% more O2 than maternal hemoglobin

• baby has 50% more hmg than mom

• baby will take iron form mom wether she has enough or not, she may likely end up anemic

supine hypotension

• when mom lies on back, pressure from baby compresses vena cava

• diminishes blood return and lowers BP

• mom can get faint and nauseas

• mom should lie on her Left side and upper body elevated

umbilical vein

• carries oxygenated blood to the fetal liver to perfuse hepatic portal vein and to ductus venosus

ductus venosus

• located in liver

• majority of blood is shunted to inferior vena cava

• blood enters right atrium

foramen ovale

• located between right and left atrium

• shunts blood from right atrium to the left atrium (bypasses the right ventricle & lungs)

ductus arteriosus

• after the blood goes to the left atrium and ventricle, it goes to pulmonary artery

• connects pulmonary artery to the aorta

• bypasses lungs and brings blood straight to aorta to perfuse the rest of the fetus

2 umbilical arteries

• carry deoxygenated blood from descending aorta back to placenta

• some deoxygenated blood will enter back into heart via inferior vena cava

how are the shunts able to function in utero

• the high pressure from fluid filled lungs

• after birth when the lungs are clear of fluid, the pressure lessens and the foramen ovale is not able to function and closes off

how does the ductus arteriosus close off after birth

• when umbilical is cut, the prostaglandins decrease which closes the shunt

in the first 24 hours after birth

• shunts can still be heard as a murmurs

• usually means nothing in first 24 hours unless accompanied by other issues

GI system

• matures by 38 weeks

• gastric emptying and peristalsis at month 5

• baby produces meconium with peristalsis in utero

if baby has a BM in utero?

• if baby has a BM in utero meconium could go to lungs and lead to aspiration

• usually won’t happen unless baby is under stress

• greater chance if baby is not delivered by term

Hepatic system

• liver and biliary tract form by week 4

• glycogen storage by wk 9-10

• glycogen storage is double than an adult @ term bc they need more energy storage under stress

• iron stores iron to last 5 months post birth

what could put a baby under stress

• being cold

• respiratory problems

• hypoxia

bilirubin in utero

• fetus liver doesn’t process bilirubin , placenta does

• after birth, baby needs to process bilirubin

• predisposed to hyperbilirubinemia → jaundice

Coagulation factors

• can’t be synthesized in fetal liver bc of lack of vitamin. K

• vitamin k given @ birth

respiratory system

• starts to develop @ wk 4

• fully develops at wk 17

• wk 24 - term: surfactant is secreted

when does baby have sufficient surfactant levels

32 weeks

renal system

• kidneys form @ wk 5

• function @ wk 9

• urine secreted into amniotic fluid

• cortisol levels rise as due date approaches

• newborns need to void in 24 hours after birth

nuerologic system

• spinal cord develops from long end of neural tube

• @ term fetal brain is ¼ size of an adult brain

• eyelids are fused until 24-26 wks

thyroid develops @?

wks 3-4

reproductive system

• characteristic appear at 9 weeks

• fully differentiated at 12 weeks

• girls are born with total supply of ova (eggs)

musculoskeletal system

• bones and muscles start to develop at wk 4

integumentary system (vernix & lanugo)

• vernix is thick @ 24 wks and is scant by term

• leave the vernix once baby comes out

• lanugo - covered @ 20 wks , scant by term

integumentary system (hair and nails)

• eyebrows @ wk 12

• nails @ 10 wks

• do not cut nails in hospitals, fingers are very vascular

immunologic systen

• IgG crosses placenta

• fetus makes IgM

• IgA found in colostrum

dizygotic twins

• fraternal

• 2 different ova → 2 different babies

• 70% of all twins

• risk increases with age, parity and ART

• more common in black women

monozygotic

• identical & same sex

• 1 ova that divides → 2 babies

• 0.4% of all pregnancies

• babies that share the same sac and placenta are at a higher risk of umbilical twisting than babies with their own sac and placenta

conjoined twins

• splitting is not complete and occurs late

• always from monozygotic twins

what hormones cause the changes to anatomy and physiology in pregnancy

high levels of estrogen and progesterone

how does the uterus weight change during pregnancy

from 4-70g to 1200g @ term

how does the uterus volume and shape change during pregnancy

from 10 ml to 5 liters @ term

goes from pear shaped to globular

at 7wks, 10 wks and 12 weeks, how big is the uterus

7 - hen gg

10 - orange 2x original size

12 wks - grapefruit

when does the uterus rise to the abdominal cavity

12 weeks

when do women show?

14 weeks, may be earlier in multiparity

where is the uterus palpated at 12-14 weeks vs 20-22 weeks vs term

symphysis pubis , then umbilicus , will go up to typhoid process by term

lightening

between 38-40 weeks, fundal height decreases to just below zyphoid proccess

• happens 2 weeks before birth in nulliparity

• multiparty: 2 wks or right before before labor

Hagars sign

• assesses compressibility and softening of isthmus(Lower utuerus) while cervix is firm

• bimanual exam by practitioner

• @ 6 wks

Braxton hicks

• intermittent contraction felt after mo. 4

• not labor, not painful

• feels better as women move around

• preterm labor is often missed bc women think its Braxton hicks

how does uteroplacental blood flow change in pregnancy

• increases by 10 fold bc of estrogen

• 1/6 of entire maternal blood in in uterine vasculature

• uterine contractions can decrease blood and O2 to baby

bellottement

• passive movement of unengaged fetuss

• palpates uterus and baby moves

• recognized at 16-18 weeks

quickening

• 14-18 weeks (earlier in multiparty)

• firs recognition of baby movement

• "flutter” feeling

cervix changes in pregnancy

• firm closed structure to maintain pregnancy

• may become for friable (easy to bleed after exam/ sex)

• in labor, it become elastic, dilates and eface (shortens)

Goodall sign

• softening of cervical tip

• probable sign of pregnancy @ 6th week

• due to increased vascularity and hyperplasia

operculum

• formation of mucus plug

• barrier for bacteria (contains endocervical cells and immunoglobulins)

cycle changes during pregnancy

• no ovulation or menstruation

• suppressed FSH and LH

• increased estrogen and progesterone

vagnial and vulva changes

• enlarges

• increases sensitivity

• edema

• varicosities

Chadwick sign

• increased vascularity makes mucosa and cervix violet blue

• @6-8 weeks

leukorrhea

• white/ gray discharge with fainty odor

• should not be green or have a foul odor

• from stimulation of cervical cells

ph of vagina changes

• becomes more acidic (3.5-6)

• prevents infection that lead to preterm labor

• makes mom more vulnerable to candidiases

breast changes

• fullness

• increases sensitivity (may be painful)

• increased pigmentation

• stretch marks

• increased vascularity

lactogenesis stage 1

• estrogen stems growth and proliferation of milk ducts

• progesterone - development of mammary lobes

• prolactin - production of colostrum

• HPG - produces colostrum in 2nd trimester

blood volume changes

• increases 40-50%

• peaks @ 32 weeks

• rapidly rises during 1st half

• protective and hydration factors

• dependent edema: swelling in feet when they are not elevated

cardiac output

• increases 30-50% during pregnancy

• peaks @ 25-30 weeks, declines 20% @ 40 wks

  • blood pressure changes

how much does HR increase

10-20 beats/min

vena cava / supine hypotensions syndrome

• when mom lies on back her inferior vena ova is compressed and decreased blood flow to heart

• BP drops

• mom should lay on L side with elevated head

structural cardiac changes

• heart is elevated and rotated forward to the left

• apical pulse is found higher and more lateral 1-1.5cm

blood component changes

• increase in RBCs

• decreases H & H , anemia

• 5-6X more at risk for thromboembolic issues

• higher risk if there is more blood loss in labor

structural changes of respiratory system

• O2 consumption increases by 20-40%

• chest breathing replaces abdominal breathing (diaphragm pushed up)

• may have dyspnea, gets better with lightening

• nasal congestion due to vasodilation

functional respiratory changes

• tidal volume increases by 40%

• chronic mild hyperventilation

• rate will not change

GI changes

• nausea/ vomiting @ 4-12 wks (peaks @ 9)

• epulis - red nodule on gums

• pytalism - excessive slaivation

• pyrosis - heartburn (progesterone effects heart smooth muscle)

• constipation (progesterone effects heart smooth muscle)

• microbiome changes

• iron absorbed more readily

• abd discomfort - round ligament pain

gallbladder and liver changes

• may get gallstones from thicker bile

• decreased emptying time

GU changes

• pressure on bladder from enlarging uterus

• kidneys enlarge

• ureter dilates

• increase in voiding

• irritability of bladder mimicking UTI

• GFR increases by 50%

fluid and electrolyte changes changes

integumentary system changes

• hyperpigmentation of alveoli, nipple, vulva, axilla, stimulated by melanotropin

• hair/ nail growth

• acne changes

melasma / cholasma

• “mask of preganancy“

• blotchy dark spots of cheeks , nose forehead

• more likely in darker skin

• 16th week and on

• increases until term, fades after birth

• intensified by sun