Fetal development in first trimester
All major organ systems develop
Fetal development in second trimester
Completion of organ development
Placenta produces sufficient progesterone to maintain endometrial lining and continue through pregnancy
Fetal development in third trimester
Fetal weight gain
Estrogen production by placenta accelerates at the end of the trimester to stimulate labour and delivery
Pre-embryonic stage
0-2 weeks
Cell multiplication and differentiation
Embryonic stage
4-8 weeks
Body systems form and heart begins beating
Fetal stage
> 8 weeks
Rest of development occurs
Functions of placenta
Develops 3 weeks after fertilization
- Temporary blood rich organ
- Transfers heat
- Gas exchange of CO2 and O2
- Delivers nutrients (glucose, K+, Na+, Cl-)
- Carries away waste (urea, uric acid, creatinine)
- Serves as an early liver
- Barrier against harmful substances
- Endocrine gland that secretes hormones throughout pregnancy
Waste products carried away by placenta
Urea - breakdown of proteins
Uric acid - breakdown of purine
Creatinine - waste product by muscles
Major cardiovascular changes during pregnancy
Increased blood volume Increased plasma volume Increased RBCs Increased risk of thrombosis Increased heart size Increased heart rate Decreased blood pressure Increased stroke volume and cardiac output Increased workload on heart Sensitivity to position
Supine hypotension syndrome
Compression of vena cava, abdominal aorta, pelvic and femoral arteries
If pressure not released:
- decreased cardiac output
- decreased blood pressure
- lower extremity edema
Wharton’s jelly
Gelatinous substance that prevents kinking of umbilical cord
Has a high water content for fast shrinkage after birth
Function of amniotic fluid
- Protects fetus from trauma
- Separates fetus from fetal membrane
- Permits fetal muscle development and movement
- Facilitates symmetrical growth and development of fetus
- Helps keep temperature constant
- Acts as an excretion collection system
- Cushions the cord
4 M’s
Meconium
Multiples
Maturation
Medication
GTPALM
Gravida Term Preterm Abortions Living Multiples
Estimated date of confinement (due date)
First day of last menstrual period, add 7 days, subtract 3 months
Fetal alcohol syndrome
Thought to constrict blood vessels and send them into spasms, reducing blood flow to the baby
Leading cause of birth defects
Effects of tobacco on fetus
Decreased fetal growth Increased spontaneous abortion Increased SIDS deaths Increased premature rupture of membranes Increased premature labour
Spontaneous or induced abortion
Termination of pregnancy before 20 weeks gestation (some sources up to 28 weeks)
S/S= cramping, abdo pain, back ache, vaginal bleeding
Stages of abortion
- Threatened abortion - attempting to take place, and can progress or subside
- vaginal bleeding in first half of pregnancy; continue normal activity - Inevitable abortion - spontaneous abortion that cannot be prevented
- severe abdo pain caused by uterine contractions, vaginal bleeding, cervical dilation - Incomplete abortion - some products of conception remain in the uterus
- potential shock
- OLMC if products are protruding; fundal massage - Missed abortion - fetus dies during first 20 weeks, but remains in uterus
- gradually diminishing of s/s of pregnancy, brownish discharge - Septic abortion - uterus becomes infected
Placenta previa
Abnormal implantation of placenta on the lower half of the uterus
Total or partial
Painless vaginal bleeding in third trimester
C-section required for treatment
Abruptio placenta
Premature separation of a normally implanted uterus
Partial, sever, or complete with either concealed or apparent hemorrhage
Life threatening
S/S= sudden onset of severe abdo pain with or without bleeding
Treat for shock, fluid resuscitation, rapid transport in left lateral recumbent
Pre-eclampsia
Pregnancy induced hypertension
S/S= gradual hypertension (160-180 mmHg), proteinurea, peripheral edema, HA, N/V, rapid weight gain, visual disturbances, pulmonary edema
Effects of pre-eclampsia
Mother:
- impaired renal/liver function, cerebral hemorrhage, placenta abruption, HELLP syndrome
Fetus:
- reduced fetal growth and development
Human placental lactogen (hPL)
Cortisol, growth hormone, and progesterone cause high levels of glucose, but makes mother’s body resistant to insulin so more glucose is available to the fetus
Can cause macrosomia (large baby)
Glucose tolerance test administered at 26-28 weeks
