pregnancy

Question 1

1st trimester

Answer 1

0-13 weeks (not clear pregnant)

Question 2

2nd timester

Answer 2

13-26 weeks (clearly pregnant)

Question 3

what happens at week 26 (2nd -> 3rd timester)

Answer 3

absolute limit viability

Question 4

3rd trimester, and physical changes

Answer 4

26-39 weeks (very clearly pregnant, with abdomen large and angle of back posterior to compensate)

Question 5

what happens between weeks 37-41

Answer 5

term

Question 6

when do maternal and placental changes occur in pregnancy

Answer 6

maternal changes occur throughout, and placental changes are complex and occur mostly in first half (most risks during first trimester)

Question 7

maternal changes: 1st term (and later)

Answer 7

altered brain function, altered hormones (mainly steroids), altered appetite (quantity and quality; GI imbalance causes hyperemesis gravidarum “morning sickness”), altered emotional state (unpredictable), altered immune system (to allow pregnancy to continue but still retain resistance to disease)

Question 8

maternal changes: 2nd term (and later)

Answer 8

increased blood volume, increased blood clotting tendency, decreased blood pressure (unusual as normally increased blood clotting and increased blood pressure go together), altered fluid balance (kidneys in overdrive alongside increased blood volume)

Question 9

maternal changes: 3rd term

Answer 9

increased weight, altered joints (become more flexible)

Question 10

maternal endocrinology throughout pregnancy: HCG

Answer 10

rises during week after implantation occurs and rapidly peaks at week 9 during first trimester (measured in pregnancy test) to keep endometrium from shedding, before declining rapidly and plateauing low

Question 11

maternal endocrinology throughout pregnancy: placental lactogen

Answer 11

slow increase from week 5 to term

Question 12

maternal endocrinology throughout pregnancy: oestrogens

Answer 12

slow increase from week 5 to term

Question 13

maternal endocrinology throughout pregnancy: progesterone

Answer 13

fast constant increase to term (100x more than body has previously dealt with)

Question 14

relative risk to maternal health in early parts (1st and 2nd trimesters) of pregnancy

Answer 14

small

Question 15

what is the main risk to maternal health or life linked to

Answer 15

delivery

Question 16

fertilised egg size vs size of infant

Answer 16

<1mm -> 30cm

Question 17

define conceptus

Answer 17

everything resulting from the fertilised egg (baby, placenta, fetal membranes, umbilical cord, amniotic fluid)

Question 18

define embryo

Answer 18

baby before it is clearly human (e.g. 5-6 weeks with liver to make erythrocytes)

Question 19

define foetus

Answer 19

baby for the rest of pregnancy (3 months)

Question 20

define infant

Answer 20

less precise, normally applied after delivery

Question 21

when do blastocysts exist, and what 2 layers of cells do they contain

Answer 21

before embryo (e.g. 9 days), containing epiblast and hypoblast

Question 22

count for pregnany to ensure mother can roughly know how long

Answer 22

gestation age = first day of last menstrual period (as don’t know when ovulation occured, but usually approx. 14 days after)

Question 23

describe Carnegie stages of human development

Answer 23

summary of developmental changes, with distinct changes in development to appear more human

Question 24

significance of 2 week delay between ovulation and first day of last menstrual period

Answer 24

no huge difference at term, but viability is dramatically affected by gestational age

Question 25

how to observe pregnancy

Answer 25

observe in utero or outside (e.g. ultrasound), and with measurements by circulating factors (e.g. in blood), or dimensions

Question 26

what are used to study mechanisms of pregnancy

Answer 26

other animals (e.g. fish, chick, mouse) as similar structures develop similarly to humans, as gene families involved in development are similar

Question 27

difficulty with using other animals to model human mechanism of pregnancy

Answer 27

different pregnancy lengths etc. (but also not just size dependent), so must be cautious

Question 28

when is embryo/foetus most vulnerable to teratogen

Answer 28

during first 8 weeks as most rapidly developing, although brain vulnerable into second trimester also

Question 29

what can mal-development help to identify

Answer 29

when conceptus is most vulnerable, and which structures are most vulnerable

Question 30

describe foetal structure of placenta

Answer 30

disc (about 20cm diameter), with blood vessels and with thinner layer around called foetal layer which encloses amniotic fluid, and umbilical cord connecting to baby

Question 31

describe maternal structure of placenta

Answer 31

made up of 30-60 components (cotyledons) which are main subdivisions, with gaps between them due to maternal tissue being left behind in uterus

Question 32

describe basic placental structure of cotyledon

Answer 32

very branched structure (placental villus tree with many subdivisions for large surface area), with central stem through which blood vessels pass, where communication of materials between maternal and foetal blood supplies occur (both circulations don’t come into contact with each other, but oxygen and other nutrients exchanged from oxygenated maternal artery to deoxygenated foetal artery, before returning to foetal heart via foetal vein - similar to adult pulmonary system with respect to artery and vein oxygenation and deoxygenation)

Question 33

4 key features of placenta

Answer 33

very branched square structure provides large surface area, very effective for transport of molecules, anchors baby securely for 9 months, intimate contact between maternal and placenta tissues (plays part in immunology)

Question 34

5 functions of placenta (SEBIC)

Answer 34

separation (maternal and foetal blood systems), exchange (between blood systems), biosynthesis (very active, producing HCG, oestrogens, progesterone etc.), immunoregulation (unique with no variablity, as contains antigens to signal human, but not which human), connection (anchor)

Question 35

how does placental villous tree develop

Answer 35

starts as single layer of cells in blastocyst -> proliferate and differentiate -> branches as iterative (repeating) process to become more complicated and have a larger surface area, becoming a “placental villous tree”

Question 36

describe contact at 8 weeks gestation age to allow more growth of baby

Answer 36

spiral artery remodelling allows very large volumes of blood can access from maternal circulation to placenta during 2nd and 3rd trimesters, with cytotrophoblast shell limiting blood and oxygen supply to embryo during 1st trimester to prevent free oxygen radicals going into rapidly dividing cells

Question 37

4 outcomes of placental mal-development

Answer 37

miscarriage (late 1st trimester), miscarriage (2nd trimester), pre-eclampsia (early delivery), foetal growth restriction (small infant)