Fetal/Maternal Physiology

Why is there an apical beat shift in pregnancy

uterus is enlarged so elevates the diaphragm → pushes up on heart → left-upward displacement causes a lateral apical beat shift

How does heart volume change in pregnancy

1. Heart increases in size about 12% (both increase in myocardial mass and volume)

How does blood volume change in pregnancy

increases 50% of plasma volume triggered by pregnancy hormones (helps to compensate for blood loss at delivery)

beings 1st trimester, rapidly increase in 2nd, plateau in 3rd

how much does cardiac output increase in pregnancy

40% (due to hormonal changes)

how much does heart rate increase in pregnancy

increases 15 bmp in resting maternal heart rate

True or False: primiparous women experience more profound effect on maternal CV system

FALSE: Multiple gestations have even more profound effect on maternal CV system

early sign on pregnancy from renal changes

urinary frequency

renal/bladder changes in pregnancy

1. kidney length inc 1-1.5cm

2. ureters dilate

3. bladder upward and flat

In pregnancy Renal plasma flow increases

by 50-85% above nonpregnant values

where is appendix displaced in pregnancy

superiorly in the right flank area

where is stomach and bowels displaced in pregnancy

1. Stomach is push upward

2. large and small bowels extend upward

why is heartburn common in pregnancy

1. Greater production of gastrin,

2. increases volume and acidity of gastric secretions

3. Dilated lower esophageal sphincter-reflux

why can constipation increase in pregnancy

Intestinal transit times are decreased in 2nd and 3rd trimesters; returns to normal in 2-4 days postpartum

→ due to progesterone

→ increased water absorption → constipation

gallbladder function in pregnancy

Slowed emptying and incomplete, risk for gallstone formation

why is there anemia in pregnancy

RBC expands by 33% and

erythropoiesis of pregnancy increases utilization of iron→ At risk for iron deficiency anemia

Placenta actively transports iron from mother to fetus, so fetus is not generally anemic even when mother is severely deficient

Which clotting factors increase significantly during pregnancy

Factor I (Fibrinogen) and Factor VIII

gestational thrombocytopenia

platelet production increases, but so does platelet consumption from extra blood circulation in placenta so platelet counts can fall below 150,000 in 6% of pregnant women in the third trimester

skin changes in pregnancy

Hyperpigmentation

1. Melasma, mask of pregnancy

2. Linea nigra

3. Striate gravidarum

what substances wont cross placenta membranes

Heparin and insulin are large molecular size

Why do protein-bound drugs have increased placental transfer in pregnancy?

Pregnancy lowers maternal albumin levels → fewer binding sites → more unbound (free) drug → greater placental gradient → more drug crosses placenta.

how many umbilical arteries and function

2

blood from embryo to chorionic villi

how many umbilical veins and function

1

returns blood to embryo

Wharton’s Jelly

connective tissue surrounding arteries and vein of umbilical cord

how big is mature umbilical cord

50-60cm (length)

12mm (diameter)

what can alter the normal sequences of Organs maturation

Preterm or complicated delivery

Foramen ovale

connection between the two atria

Ductus arteriosus

between pulmonary artery and arch of the aorta

What causes a rise in systemic vascular resistance at birth

Cessation of placental blood flow

What event triggers the fall in pulmonary vascular resistance after birth

The newborn's first few breaths → pulm resistence dc → foramen ovale closes and ductus arteriosus constricts

describe alveoli in gestation vs after birth

fetus → filled w fluid and lots of surfactant

after breathing at birth → air replace fluid → Surfactant already lining the alveoli spreads out along the inside of the alveoli.

purpose of surfactant

decrease surface tension at the end of expiration

what to do if drying and suctioning do not induce respirations

additional tactile stimulation→ Slapping or flicking the soles of the feet or Rubbing the infant’s back

after 30 seconds →begin resuscitation measures

what pulse indicates distress in newborn

<100 bpm