Sept12 M3-Normal pregnancy and antenatal care Flashcards
placental dev
- trophoblast forms placenta with cyto and syncytio trophoblasts (cells). implants in endometrium
- primary and secondary villi of the placenta are formed (lacunae are formed by syncytios and then endometrial caps degen and their blood goes in lacunae)
abnormal placentation def (implantation)
excessive invasion of the placenta. it implants too deep in the uterus
maternal surface of the placenta
- discoid chorionic plate (decidual plate) with lobes, cotyledons, placental septae)
- looks like liver
- is a seventh of the fetus weight at term (500g)
fetal surface of placenta
-amnion and chorion, fetal vessels
hormones secreted during pregnancy
- placenta makes hCG (maintains CL), hPL (human placental lactogen), E and P
- pituitary, adrenal and thyroid Hs from mom
- fetal adrenal hormones
2 main cells of placenta
- cytotrophoblasts
- syncytiotrophoblasts
first hormone appearing a few days after implantation
hCG (produce by syncytiotrophoblasts).
hCG functions
- act on ovary to maintain CL and make it prod E + P
- act on thyroid to make it prod more TH (so TSH will drop in T1)
- stims prod of testo from fetal testis (if it’s a male) bc hCG is similar to LH (common alpha subunit. so hCG can act on LH-Rs)
hCG in normal intrauterine pregnancy
doubles every 48 hours DURING T1. then low range later in pregnancy
human placental lactogen fct
- proportion of hPL rises proportionally to placental mass (rises all throughout pregnancy)
- diabetogenic effect on the mother (more serum glucose, more lipolysis, less insulin action)
gestation diabetes mellitus (GDM) is caused by what
hPL
why CL stops making P after the first few weeks of pregnancy
fetal adrenals start making DHEA-S precusor which is aromatased by the placenta into estrogen
estrogen effect on the mother during pregnancy
- higher uterine blood flow and growth
- PG synthesis
- prolactin secretion
- other effects for maternal adapt to pregnancy
uterus changes how in pregnancy
- 50g in beginning. 950 at term
- initially hypertrophies. then distends at end of pregnancy
cervix and vagina in pregnancy
- cervix soften (ripening)
2. vagina mucosa thickens and stretches more easily
when does the uterus get out of the pelvis in pregnancy
at 12 weeks
when does uterus reach the belly button in pregnancy
20 weeks
uterus position in the body at term
xiphoid process (38 weeks. at 40 weeks bit lower bc baby engages)
why CL stops making P after 8 weeks of pregnancy
P starts coming from placenta (like E but the precursor is made by the mother not the baby (DHEAS for E).
the precursor is cholesterol (LDL) and placenta makes it into progesterone
P effect in pregnancy
For implantation of the blastocyst:
-less T lumphocyte resp and less graft rejection and immune resp (if strong, will reject the baby)
-less uterine contractions
-less PG formation
For protection against htn
-reduced angiotensin II responsiveness so SM relaxes
CV changes in pregnancy
- higher HR, higher SV. higher CO
- higher central blood volume (estr) (bc of more RBCs which increases the serum)
- less peripheral resistance (due to vasodilation from P)
- redistribution to blood flow to kidneys and uterus. higher GFR**. uterus P on venous return = varicose veins, hemorrhoids, distended veins, varicosities.
BP changes in pregnancy
BP drops. lowest at 20 wks (orthostatic hypotn)
resp changes in pregnancy
- higher tidal volume (flared ribs)
- more O2 consumption
- higher RR. possible SOB
GI changes in pregnancy
- hypertrophic gums (gingivitis of pregnancy)
- nausea and hyper-emesis, bc of HCG and E2
- acid reflex bc of weak LES bc of estrogen
- constipation
renal changes in pregnancy
- ureteric dilation (stasis, UTI) (Prog)
- increased water excretion (higher freq of voiding)
- increased renal blood flow (GFR)
- occasional proteinuria, glycosuria
E and P during pregnancy
both increasing
- E: increased uterus size and blood flow. softer CT. breast dev and PRL. water retention
- Prog: reduces smooth muscle excitability in myometrium, ureters, vessels, GIT, brain
skin changes in pregnancy
- striae gravidarum (stretch marks on abdomen. back to normal after 6-8 months postpartum bc of collagen reorganization)
- chloasma (sometimes reversible) = pregnancy mask = facial hyperpigm
- linea nigra = black line in body midline (reversible after 6 months postpartum)
cause of skin changes in pregnancy
hormones
changes in HP axis in pregnancy
- higher ACTH
- higher TRH
- higher prolactin (rising up to 30 wks)
- melanocytic activity (skin changes)
- less FSH and LH secretion bc of E2 and P neg feedback + PRL effect
hematological changes in pregnancy
- lower iron stores (may need Hb if iron too low)
- higher blood volume (more plasma and more RBCs
- higher WBCs (is a compensatory mechanism for decreased immune fct)
- Hb progressively dropping until delivery
hematological complications in pregnancy
- increased risk of DVT and PE (aco if FHx or PMHx present)
- increased risk of infection (bc of decreased immune fct): influenza and varicella vaccine in pregnancies*
normal weight gain in pregnancy
12-15 kg mean
dangers of dieting in pregnancy
- poor weight gain = pre term delivery
- excess weight gain = GDM
what is a high risk pregnancy in antenatal care
- pre-existing disease
- previous pregnancy complications
- current pregnancy complications
principles of antenatal care first visit
- PMHx with meds
- obstetric assessment
- PE including breast , thyroid, cardiac. + pap, gono and chlam culture
- trisomy 21 screening discussion
- prenatal bloods (infections like HIV, Hep B, rubella, VDRL. CBC, blood type and Ab screen, TSH, random glucose, Hb electrophoresis)
- UA + urine culture
urine bacteriuria in pregnancy charact
- is abnormal in pregnancy (whereas is normal in other times if is not symptomatic)
- increases risk of pre term delivery
frequency of antenatal visits
- every 4 weeks before 30 weeks
- every 2 weeks from 30 to 35 weeks
- every week after
other steps of antenatal care after first visit
- viability US
- T21 screen results
- screen for GDM
- Dtap vaccination (diphtheria, tetanus pertussis), rhogam (Rho(D) Ig) administration if Rh- (pertussis abx cross placenta)
- growth US
- GBS screen
example of two teratogenic meds commonly used
- ACEis
- ARBs
PEs on subsequent antenatal visits
- fetal auscultation
- inspect legs for edema
- BP
- obstetrical assessment
- weight measurement
- fundal height measurement (should be nbr of weeks +- 3) (symphysis to fundus)
how to assess the fetal presentation and descent
as of 30 wees
- manual exam
- ultrasound
normal HR of fetus
- 170 during pregnancy
- 120-130 at birth
- normal values at age 2-3
when to give intrapartum Abx (during labour)
- positive GBS screen
- GBS bacteriuria
- previous child affected by GBS
- signs of chorioamnionitis (fetal tachycardia, fever)
