Physiology of Pregnancy + Drugs Flashcards
What happens to blood volume, RBC and flow in pregnancy and what does this lead too
Increases
RBC increase by up to 40%
Produces physiological anaemia
What happens to systemic vascular resistance
Decreases
What happens to BP in pregnancy and why
Drops due to drop in resistance + relaxation due to progesterone
Usually returns to normal by 3rd trimester
What happens to CO
Increases due to drop in afterload and increase in SV + HR
What happens to after load, SV + HR
Afterload drops due to drop in resistance
SV and HR increases due to increased O2 demand
What position for pregnant women in resus?
Left lateral
Lying supine reduces CO. by 25% as IVC squashed
Why does 02 demand increase
Increased metabolism
What happens to TV and RR
Increases as increased O2 demand
SOB due to increased RR = physiological but careful of PE
Can lead to mild alkalosis on blood - also due to increased HCO3
What happens to PEFR and FEV1
Unchanged
What does progesterone do
Causes bronchodilator
Asthmatic have less problems in pregnancy
What happens to gut motility and peristalsis and what does this increase risk of
Decreases
Due to smooth muscle relaxation by progesterone
GORD
What happens to intra-abdominal pressure
Increases
What happens to GFR
Increases as increased CO
What happens to creatinine and urea
Increased clearance
Lower levels in pregnancy suggest renal failure
What happens to protein
Increased excretion causing oedema
What happens to ureters
Dilatation and hydronephrosis
Why are pregnant women prone to UTI
Short urethra
Stasis by progesterone
Can cause pre-term labour
Microscopic haematuria common in pregnancy
What happens to urate
Urate increases the same as no of weeks gestation
Why is glycosuria common in pregnancy
Pregnancy is anti-insulin
If that is only symptom the n don’t worry
What happens to iron requirements
Increase
What happens to WCC
Increase but doesn’t mean infection
What happens to platelets
Decrease
What happens to Hg, Hcrit and RBC
Decrease
What happens to CRP
Stays the same so use as marker of infection
What happens to ESR
Increases so can’t use
What happens to liver enzymes - AST / ALT / GGT
Decrease
What happens to alkaline phospate
Increases as produced by placenta
What happens to bile acid
The same
What happens to d-dimer
Increases so can’t use for PE
Must do V/Q scan as CTPA CI
What happens to your thyroid?
Enlarged to trap more iodine as kidneys secrete more
If iodine deficient may develop a goitre
What makes morning sickness worse
Higher B-hCG
Molar / twins
Usually improves by 16 weeks
What is hyperemesis gravidrum
Severe N+V in pregnancy
What happens to HCO3
Increases
What occurs doe to reduced peristalsis
Constipation
What happens to drug absorption
Decreased as D+V + reduced motility
Increased IM due to increased blood flow
What happens to hepatic blood flow
Unchanged
What happens to NaCl and H20 l in kidney
Increased reabsorption
What happens to iron / folate / ca requirement
Increase
What do you need iodine for
Healthy brain + bone
Metabolism
What happens to breast
Increase in size and vascularity
Warm and tender
What are other general adaptions
Immunosuppressed as fetes foreign body
Weight gain 2-10kg
Increased relaxation
Curvature of spine change
What is gravity
Number of times women IS or HAS been pregnant regardless of outcome Twins count as 1 Nulli = none Prim = 1st pregnancy Multi = >1
What is parity
Number of pregnancy >24 weeks
1+2 = 1 >24 weeks and 2 didn’t make
What are Braxton Hicks
Non painful contractions
Later on in pregnancy - 3rd trimester
Irregular
Where do you get info about drugs in pregnancy
BNF
UK tetrology
Drug and lactation database
What are principles of prescribing in pregnancy
Avoid unneccesary Use drugs with best safety Avoid new drugs Use lowest dose for shortest time Avoid 1st 10 weeks Stop or reduce before delivery If safe in<2 should be safe in breast Choose highly protein bound
How is absorption, distribution, metabolism and excretion affected by pregnancy
Absorption - N+V, decreased motility, increased IM and respiratory
Distribution - decreased plasma protein
Metabolism - increased
Excretion - increased GFR so plasma conc may decrease
What happens to drugs in fetal circulation
Less protein so increased drug
Little fat
Reduced enzymes
What does placental transfer depend on
Weight - smal
Polarity - non polar
Lipid solubility
What is teratogenicity
1st trimester
What do folate antagonists cause
Need folate for DNA
Neural tube
Face and limb defects
What are folate antagonist
Methotrexate
Trimethoprim
Nitrofurantoin
AED
What should you do for methotrexate
Stop 6 months prior
What should you do for trimethoprim
Do not give in 1st trimester
What should you do for nitrafurantoin
Not in 3rd trimester
Cause haemolytic anaemia
What do retinoid drugs cause
Aortic arch anomaly
VSD
Face malformation
Oesophageal atresia
LD
Endocrine
In-utero death
What do retinoids require
Contraception
What do anti-convulsants cause
Neural tube defect
What do anti-coag cause
Haemorrhage
CNS
MSK
What does ACEI cause
Renal dysgenesis
Growth
What does NSAID cause
Premature closure of ductus arteriosus
What does alcohol cause
SGA Pre-mature Miscarriage FAS Withdrawal
What do opioids cause
NAS
Resp depressio
What does cocaine cause
Vasoconstriction Hypertension Abruption Premature IUGR NAS
When do you avoid aspirin
Labour
Risk of bleed
Zika
Microcephaly
What does smoking cause
IUGR Pre-term Placental abruption Pre-eclampsia Cleft palate /lip Miscarriage Stillbirth
Thialimiide
Absent limb
Phenytoin / Carbamazepine
Neural tube defect
GDD
Tetracyclne
Yellow teeth
SSRI
Congenital HD
Pulmonary hypertension in 3rd
What is fetotoxicity
2nd / 3rd trimster insult
Functional and growth defect
What drugs should be avoided in breast feeding
Cytotoxic Immunosuppression Aspirin Amiadarone Lithium Iodine Tetracyclien / sulphonamide / quinolone
What does CVS changes cause
Ejection systolic
Forceful apex
3rd HS
What Ax CANNOT be used in pregnancy
Tetracycline Aminoglycoside Sulphonamide Trimethoprim Quinolones
What other drugs should be stopped
ACEI Statin Warfarin Sulphonurea Retinoids Cytotoxic
Aminoglycoside
Ototoxicity
Lithium
Ebsteins
