MR Third Month to Birth: The Fetus and Placenta

what is IUGR

term given to babies that are pathologically small

what is SGA

healthy babies that are below the 10 procentile of weight (dus small but healthy)

A fetus born during the sixth or the beginning of the seventh month has difficulty surviving, why

because the respiratory and neurvous system have not differentiated sufficiently

during which months is fetal length growth most rapid

3-5 months

during which monts is fetal wieght gain most significant

last 2 months

what does the placenta consist of

1. fetal (derived from chorion frondosum or villus chorion)

2. maternal (derived from decidua basalis)

space inbetween = maternal blood

what are the main functions of the placenta

• gas exchange

• nutrient transfer

• antibody transfer

• hormone production

• drug detoxification

what seperates fetal from maternal circulation

1. syncytial membrane (developed from chorion)

2. endothelial cells from fetal capillaries

crown-rump length (CRL)

sitting length of fetus (vanaf wk 8 fetus ipv embryo)

what is the length of pregnancy

280 days, 40 weeks after onset last normal menstrual period (LNMP)

more accurate = 266 days, 38 weeks after fertilization

what is one of the most striking changes taking place during fetal life

the slowing down of head growth (eerst ½ van lichaam, wordt 1/4)

3 stages of labour

1. effacement and dialation of the cervix

2. dilvery of fetus

3. dilervy of placenta

if baby is born much later than calculated delivery date

post mature (ipv premature)

what is a maor growth promoting factor before (and after birth) and what happens its mutated

IGF-1, mutations result in IUGR and the growth reatrdation continues after birth → Laron dwarfism

what is a preterm baby

baby borm before 37 wks of gestation (premature baby shows sign of immaturity in organ systems)

what is hydramnios, polyhydramnios, oligohydramnios

hydramnious and polyhydramnios = excess amniotic fluid

the term used for shortage of amniotic fluid

what are primary causes of hydramnios

• maternal diabetes

• congenital malformations (eg anencephaly, gastrointestinal defects)

• idiopathic causes

these all prevent the fetus from swallowing

faternal twins have and result from

2 amnions

2 chorions

2 placentas (sometimes fused if really close together, de twins hebben dan 2 types of red blood cells = erythrocyte mosaicism)

fraternal twins result from simultaneous shedding of two oocytes that are fertilized by diff sperms (echt 2 seperate zygotes)

monozygotic (=identical) twins have and result from

2 amnions

1 chorions (hierdoor kun je onthouden dat chorion buiten om amnion zit)

1 placenta

monozygotic twins result from splitting of the zygote at various stages, depending on stage of split, they can have diff combinations of placenta chorion and amnion (dus shared of niet)

if before blastocyst: they implant seperatly en have 2 of each

conjoined twins have and result from

1 amnion

1 chorion

1 placenta

conjoined twins form is splitting of monozygotic embryo occurs during the bilamniar germ disc stage or splitting of primitive node and streak

what is vanishing twin

death of one of the twin fetuses

twin–twin transfusion syndrome

one of the twins receives most of the blood flow and grow larger, usually both twins die

TRAP

twins have 2 seperate placenta’s close to each other, but one twin is further in development, resulting in a higher fetal pressure, causing a reverse flow in the other fetus (arteries are O2 rich and go to the lower body first), before blood reaches the 2nd fetus, it has already passed through the first fetus, so it doesnt have enough oxygen anymore to develop organs. other baby may die due to heartfailure (his heart has to beat for both babies)