Physiology of Pregnancy Flashcards
T/F the fetus is susceptible to teratogens in the first 1-2 weeks of pregnancy
False; the first ‘2 weeks of pregnancy’ are days 1-14 (ovulation) and actually before conception; during days 14-28 (4 weeks pregnant) teratogens are not thought to have effects because the organ systems don’t start developing until 4 weeks
Early pregnancy is considered to be
weeks 3-4, ie after conception (4 weeks from LMP)
Embryonic phase is from week
3-8 (5-10 from LMP)
Fetal phase is from week
9-38 (term; 11-40 from LMP)
Congenital malformations to organ systems are programmed during what phase of development?
Embryonic phase - weeks 3-8 from conception
The fetus is considered to be fully functioning at the end of week
8 (10 since LMP)
The foetal period is characterized by
exponential growth and maturation of the organ systems
Issues that face growth and development during the fetal period result in
functional deficits in the organ systems; can be some minor morphological abnormalities
Human chorionic gonadotropin is produced by
the trophoblast (becomes placenta)
The membranes surrounding the fetus are
amnion (inner) and chorion (outer)
The role of the fetal membranes is
protect fetus and allow fluid transfer (but mainly goes through umbilical cord)
The umbilical vein carries __________ blood and the umbilical arteries (2) carry ________ blood
vein carries the oxygenated blood; 2 arteries carry deoxygenated blood (and waste products)
The placenta is formed from
trophoblast cells that invade the endometrium
What are blood lakes within the placenta?
invasion of trophoblast cells into the endometrium breaks down uterine blood vessels and arterioles forming lakes; chorionic vili contain embryonic blood vessels (foetal capillaries) extending into the lakes
What is the purpose of formation of blood lakes?
These regions are safe from vasoactive/vasoconstrictive agents affecting the mother (eg stress, exercise, increased BP) tf the fetal blood supply is not affected by them (exception is pre-eclampsia)
Amniotic fluid is composed of
urine, liquid from lungs
T/F the gut is inactive during development
False; it is fully functioning though nutrition comes via teh umbilical vein; the foetus swallows amniotic fluid which helps with development
T/F the kidneys are functional during development
True; they are producing urine that goes into the amniotic sac; waste products still exit via umbilical arteries
Amniotic fluid functions
as a buffer; allows foetal movements and growth; development of GI
Oligohydramnios
low amniotic fluid volume; can be detrimental to foetal growth, lung growth, and movements
Placental function surmises which organ systems?
Lungs, kidneys, GIT
T/F exercise is dangerous in pregnancy
False; as long as uteroplacental blood flow is regulated and maintained and blood flow is not shunted excessively to muscles
Which hormones are produced by the placenta?
hCG, human placental lactogen (hPL), estrogen and progesterone
hCG from the placenta functions to
rescue the corpus luteum so it can take over for LH and FSH which have declined
human placental lactogen (hPL) from the placenta functions
in breast development and maternal metabolic effects
Estrogen and progesterone from the placenta function
essentially for almost all of the pregnancy adaptations and maintenance; major role in breast development
Other hormones produced by the placenta include
growth factors, CRH, ACTH
Monozygotic twins arise from
one zygote that splits and forms 2 embryos; tf they are genetically identical and the same sex because they come from a single fertilized ovum
Dizygotic (fraternal) twins arise from
2 oocytes ovulated and fertilized by 2 separate sperm; tf they are non genetically identical and can be the same or different sex
Development and maturation of organ systems through the foetal period is largely driven by
cortisol
What must occur prior to labour?
Maturation of the fetal organs and softening of the cervix
What must occur during labour?
dilation of cervix (1ocm); rhythmic uterine contractions of the myometrium (outer muscle layer); once initiated maintained by positive feedback - eg oxytocin
Parturition is triggered by
CRH, ACTH cascade, hormones from placenta and fetus, cervical stretch as the baby drops lower in the uterus, oxytocin from the posterior pituitary (uterine contraction and lactation), prostaglandins from the uterine wall stimulate contractions
What is the role of cervical stretch in parturition?
As the fetus drops lower in the uterus, the cervix stretches, upregulating oxytocin release from the posterior pituitary and triggering uterine contraction that furthers cervical stretch
What is the role of oxytocin in parturition?
Triggers uterine contractions and prostaglandin release from the uterine wall in response to stretch of the cervix; contraction to deliver the placenta
What is the role of prostaglandins in parturition?
Stimulated release from uterine wall by oxytocin, facilitate uterine contraction
During pregnancy, ___________ stimulate development of mammary glands
estrogen, GH, cortisol
Late in pregnancy, ________ stimulates conversion of mammary ducts to _____________
progesterone; secretory epithelia capable of producing milk
Before birth, lactation
is suppressed by prolactin-inhibiting hormone (PIH); milk production is inhibited by high estrogen and progesterone
After birth, lactation
is stimulated by high levels of prolactin and low levels of estrogen
What is the benefit of breast milk?
It contains all the nutrients and immunity needed specifically by the infant to survive
Suckling inhibits
PIH
Prolactin stimulates
production of milk
Oxytocin in lactation stimulates
milk ejection in response to suckling
Lactation inhibits ______ which inhibits _________
GnRH - the ovarian cycle and ovulation to prevent another pregnancy - natural birth spacing
Suckling stimulates
inhibition of PIH/production of prolactin to stimulate milk production (next feed) and oxytocin for milk ejection (current feed)
