The Prenatal Journey pt 2

Fertilization

cellular multiplication

Pre-embryonic period

• first 2 weeks after conception

• rapid cellular multiplication and differentiation

Embryonic period

• from 3rd week after fertilization through end of 8th week

• fetus at 8 weeks

Yolk sac

• develops 8-9 days after conception

• essential for transfer of nutrients during 2nd-3rd weeks of gestation

• hematopoiesis until week 8 when fetal liver takes over

• atrophies and is incorporated into umbilical cord

When does the placenta take over?

12 weeks

Circulation

• heart begins to beat and circulate blood by end of 3rd week

• heartbeat visible on ultrasound by week 6

• umbilical vein (ONE)

• umbilical artery (TWO)

Umbilical vein

ONE VEIN - oxygenated blood from placenta to fetus

Umbilical artery

TWO - removes waste, deoxygenated blood from fetus to placenta

Placental formation

• develops from trophoblastic cells and is well established by 8-10 weeks and fully functional at 12 weeks

• protects fetus and provides oxygenation, nutrition, waste elimination, and hormones

Amniotic membranes

• early protective structures

• 2 separate membranes

• amnion and chorion

• slightly adherent, form amniotic sac

Amnion

inner amniotic membrane

Chorion

outer amniotic membrane

Amniotic fluids

• fetal urine and lung secretions primary contributors in late gestation

  • mainly water before 20 weeks

• slightly alkaline

• contains antibacterial, other protective substances

• important for muscle development/movement

Umbilical cord

• usually located in the center of the placenta

• approx. 55 cm long (21 in); 1-2 cm diameter

• 1 vein, 2 arteries

• Wharton’s jelly

Wharton’s jelly

protects umbilical cord from compression

When is the first trimester?

conception to 12 weeks

First trimester

• transforms from embryo to fetus by week 8

• organogenesis complete by week 9

• heartbeat by Doppler by week 10

• face with recognizable features by week 10

Estimated length by end of first trimester?

5-6 inches

Estimated weight by end of first trimester?

2 oz

When is the second trimester?

13 to 27 weeks

Second trimester

• a time of rapid growth and organ refinement

• lanugo present/quickening by week 20

• fetal respiratory movements and surfactant production by week 24

Lanugo

fine hair all over the body, provide cushion by binding to vernix (white cheesy stuff)

Surfactant

in the alveoli to help decrease surface tension to keep them open

Age of viability?

24 weeks (debatable)

Estimated length by end of second trimester?

14-15 inches

Estimated weight by end of second trimester?

2 lbs 12 oz

When is the third trimester?

28-40 weeks

Third trimester

• eyes are open by week 28

• rapid brain development

• full lung maturity by week 36

• complete SQ fat deposition by week 38

Estimated length in third trimester?

19-21 inches

Estimated weight in third trimester?

7-8 lbs

Hormonal changes before conception

pituitary hormones

• affect ovarian follicular development

• prompt ovulation

• stimulate the uterine lining

Hormonal changes after conception

ovarian hormones

• maintain endometrium

• aid in implantation

• decrease uterine contractility

• initiate breast ductal system development

Estrogen

• promoted enlargement of genitals, uterus, and breasts

• increases vascularity

Progesterone

• relax smooth muscles

• decrease uterine contractility

• relaxes pelvic joints/ligaments

Estrogen and progesteron suppress?

FSH and LH

Hormonal changes before 12 weeks

hCG from fertilized ovum stimulates corpus luteum to make estrogen and progesterone

Hormonal changes after 12 weeks

placenta takes over in production of estrogen and progesterone

Uterine changes

• increased vascularity

• dilation of blood vessels

• hyperplasia

• hypertrophy

• development of decidua

Hyperplasia

increase in cell number; increases functionality, workload, and tissue size due to cell proliferation

Hypertrophy

increase in cell size, decreases functionality, increases workload, organelle size and contractility

Decidua

tick uterine membrane lining

Chadwick’s sign

• violet-blue color of mucosa and cervix

• increased vascularity

Leukorrhea

• white discharge

• increased mucus production

• formation of mucus plug

Hegar’s sign

softening of the lower uterine segment

Goodell’s sign

softening of cervical tip

Vaginal preparation for eventual birth

• thicker mucosa

• looser connective tissue

• hypertrophy muscles

• lengthening of vaginal vault

Acidic vaginal environment

• increased lactic acid

• protects from some organisms

• more susceptible to yeast infections

Increased vascularity and sensitivity

increased sexual interest, especially in the 2nd trimester

Breast changes

• fullness

• heaviness

• vessel dilation

• heightened sensitivity

• areolae more pigmented

• Montgomery’s tubercles

• colostrum

Montgomery’s tubercles

glands that appear as small bumps on areola

Colostrum

• liquid gold

• can appear as early as 16 weeks

• can take 3-5 days for milk production to start after delievery

Integumentary changes

• chloasma/melasma - can be permanent

• linea nigra - can resolve after 1 year

• striae gravidarum - permanent but fade

• palmar erythema - constant itching/redness of palms; can be a sign gallbladders issues

Chloasma

“mask of pregnancy”; symmetric patches of brownish/grayish hyperpigmentation

Neurological changes

• decreased attention span/concentration/memory

• HA

• carpal tunnel syndrome

• sciatica (nerve pain)

• syncope/fainting

  • BP can change DRASTICALLY so move slowly!

Musculoskeletal changes

• lordosis

• diastasis

Cardiovascular changes

• blood pressure changes (supine hypotension)

• stasis of blood in lower extremities

  • risk for varicose veins and venous thrombosis

• increased plasma (up to 50%)

• physiologic anemia and increased need for iron

• greatest risk of anemia at 32-34 weeks

• cardiac hypertrophy

• increased HR (palpitations)

• heart sounds (systolic murmors)

Supine hypotension

lying on back and become dizzy r/t uterus putting pressure on aorta and inferior vena cava which decreases blood flow

Respiratory changes

• increased oxygen consumption

• elevated diaphragm (less room!)

• increased chest circumference

• dyspnea

ENT changes

• nasal stuffiness

• congestion

• increased mucus production

• epistaxis (nose bleed)

Renal changes

• increased estrogen & progesterone

• increased blood flow

• pressure from enlarging uterus

Renal changes to monitor for

• static urine

• UTIs (increased risk)

Upper GI changes

• N/V in early pregnancy r/t hCG

• pica

• gums bleed easily

• difficulty swallowing r/t relaxation of smooth muscle

• heartburn/reflux

Lower GI changes

• abdominal discomfort

• distension

• cramping

• constipation/flatulence

• round ligament pain

• pelvic pressure

Psychosocial adaptation to pregnancy

• accepting pregnancy

• identity w/ mother role

• emotional attachment w/ fetus

• reordering personal relationships

• preparing for childbirth