Physiology of Pregnancy Flashcards
What is the average gestation period?
- 40 weeks
What are the trimester time periods?
- 1st trimester = 0-12 weeks
- 2nd trimester = 13-26 weeks
- 3rd trimester = >27 weeks
Some people talk about the 4th trimester, what is this?
- physical and emotional change for first 12 weeks following pregnancy
What is the name of the temporary organ produced during pregnancy that is involved in gestation, fetal nourishment, gas exchange and hormone secretion?
- placenta
The placenta is often referred to as the temporary organ produced during pregnancy that is involved in gestation, foetal nourishment, gas exchange and hormone secretion. What are the 3 blood vessels of the placenta?
- 2 arteries and one vein
- AVA (artery - vein - artery)
The placenta is often referred to as the temporary organ produced during pregnancy that is involved in gestation, foetal nourishment, gas exchange and hormone secretion. Specifically it has been identified as a temporary endocrine gland. What are the 3 key hormones the placenta is involved in secreting?
1 - human chorionic gonadotrophin (HCG) hormone (measured in pregnancy)
2 - progesterone
3 - oestrogen
The placenta is often referred to as the temporary organ produced during pregnancy that is involved in gestation, foetal nourishment, gas exchange and hormone secretion. Specifically it has been identified as a temporary endocrine gland secreting:
1 - human chorionic gonadotrophin (HCG) hormone (measured in pregnancy)
2 - progesterone
3 - oestrogen
What is the role of HCG?
- peaks at 12 weeks
- measured in pregnancy tests
The placenta is often referred to as the temporary organ produced during pregnancy that is involved in gestation, foetal nourishment, gas exchange and hormone secretion. Specifically it has been identified as a temporary endocrine gland secreting:
1 - human chorionic gonadotrophin (HCG) hormone (measured in pregnancy)
2 - progesterone
3 - oestrogen
What is the role of progesterone?
- placental implantation
- smooth muscle relaxation (uterus, gut and ligaments, causing supra pubic dysfunction in some women)
The placenta is often referred to as the temporary organ produced during pregnancy that is involved in gestation, foetal nourishment, gas exchange and hormone secretion. Specifically it has been identified as a temporary endocrine gland secreting:
1 - human chorionic gonadotrophin (HCG) hormone (measured in pregnancy)
2 - progesterone
3 - oestrogen
What is the role of estrogen?
- catalyst in early pregnancy
- stimulates the growth of the uterus and creates cervical changes
Human placental lactogen (hPL) is secreted by by the placenta. What is the role of hPL?
- induces maternal insulin resistance causing hyperglycaemia
- ensures foetal growth but can become pathological as seen with GDM
What is the role of oxytocin in pregnancy?
- works on smooth muscle help uterus contract to deliver the baby
- ejection of milk from the breasts
What happens to RBC count in pregnancy?
- increases by up to 25%
What happens to plasma volume count in pregnancy?
- increases by up to 40% form 2.5-3.7L
Plasma volume increases by up to 40% form 2.5-3.7L during pregnancy. What can this do to osmotic pressure?
- plasma osmotic pressure reduces due to increased plasma volume
- fluid will leave the blood into tissue, can cause swelling in pregnancy
Clotting factors increase during pregnancy. Why can this be good and bad?
- good = reduces risk of haemorrhage if they bleed
- bad = increases risk of thrombosis
Although there is an increase in plasma volume in pregnancy, this does not increase blood pressure. In fact peripheral vascular resistance is reduced, causing heart rate and stroke volume to increase and maintain cardiac output. What drives the reduced peripheral vascular resistance?
- progesterone causes vasodilation
- relaxes smooth muscle including blood vessels
In pregnancy the diaphragm is pushed upwards due to the baby. What does this do to lung volume?
- decreases by 5%
- diaphragm and intra-abdominal pressure push up into the lungs
- thoracic cage relaxes to accommodate so inspiratory capacity increases causing a barrel chest
In pregnancy what generally happens to the following variables:
- oxygen demands
- maternal pCO2
- maternal pO2
- availability of O2 to tissues to aid passive diffusion of the placenta
- increased oxygen demands (also why RBCs and plasma volume increase)
- decreased maternal pCO2
- increase in maternal pO2
- increase availability of O2 to tissues to aid passive diffusion of the placenta
What can hormonal changes do to the upper respiratory airways, causing increased secretion of something?
- hormonal changes cause mucosal oedema
- hormonal changes cause mucosal hyper-secretion
- can cause stuffy nose and snoring and sleep apnoea
What affect can progesterone have on the brain stem in terms of breathing?
- increased ventilation
- increased tidal volume and not respiratory rate
What are some of the most common changes that occur to the musculo-skeletal/dermatological systems?
- lumber lordosis
- ligamentry laxity
- stretch marks (striae gravidarum)
- skin pigmentation – Linea Nigra, melasma, darkened nipples
- carpal tunnel
- sciatica
- cramps
When we look at gastric symptoms, these are normally due to changes in the GIT. What are the 4 most common changes that occur?
- hyperemesis(nausea/sickness)
- oesophageal relaxation
- abdominal pressure (haemorrhoids and reflux)
- constipation (reduced bowel motility)
In a pregnant woman they can experience reflux. What hormone can contribute to this?
- progesterone
- relaxes the smooth muscles of the sphincter muscle at the lower end of your oesophagus
