pregnancy and placenta

• full term accepted from week 38
• pregnancy counted from last menstrual period, development is counted from fertilisation
• fertilisation is 14 days since LMP
• preorganogenesis is 2-4 weeks LMP (pre and perimplantation)
• embryonic period is 5-10 weeks LMP (placental growth and organogenesis)
• fetal period is 11 weeks LMP (function and shape, final structure formed)
• earlier malformation will cause more severe consequences
• teratogen is something which causes defects in the fetus
• spina bifida

  • neural tube remains open
  • exposure to amniotic fluid causes degradation of neural tissue in extreme cases
• rubella

  • cause postnatal problems

  cataract, glaucoma, bilateral deafness, congenital heart problems, other disabilities
• early pregnancy factor detected 2-3 days post fertilisation
• hCG detectable in week 4 (8 days post fertilisation)
• embryo's hormones support corpus luteum
• hCG insufficiency can lead to loss of pregnancy
• parental changes

  • organ squashing
  • respiratory function increases
  • digestive problems
  • weight gain (increase in blood volume as well as fetus development)
  • increased HR and stroke volume
  • increased urination and incontinence
• implantation and placenta problems

  • Gestational trophoblastic tumours (rare)

  Overgrowth of trophoblast

  Pregnancy growth looks bigger than stage

  Benign - rarely lead to choriocarcinoma

  • Ectopic pregnancy

  Implantation in uterine tubes

  Unilateral pain

  Displacement pain in shoulder

  Pregnancy has to be terminated

  • Pre-eclampsia

  20 weeks onwards or post-birth

  High blood pressure and proteinuria

  Cause pain below ribs

  May induce early
• later pregnancy problems

  • gestational diabetes
  • gestational hypothyroidism
  • obstetric cholestasis (leakage of bile salts into blood)
  • gestational transient thyrotoxicosis (increased T4 levels as hCG stiulates its production)
• fertilisation results in a zygote
• protective layer is called zona pellucida (until uterus is reached)
• ball of dividing cells is the morula
• blastocyst hatches from zona pellucida for implantation
• implantation occurs between the secretory glands and is usually in the upper quadrants
• implantation

  • blastocyst binds to uterine wall
  • generally between secretory glands
  • fully embedded by day 14
• trophoblast differentiates into

  • cytotrophoblast
  • syncytiotrophoblast
• cytotrophoblast

  • densely packed
  • create villi of the placenta
• syncytiotrophoblast

  • invasive
  • loose with gaps (lacunae)
  • layer separating blood of fetus and mother
• day 9 implantation

  • vacuoles form in syncytiotrophoblast
  • development of extraembryonic membranes (amniotic cavity and formation of yolk sac)
• day 13 implantation

  • extraembryonic cavity grows
  • mesoderm creates chorion
  • syncytiotrophoblast produces hCG
  • cytotrophoblast forms villi invading syncytiotrophoblast
• placenta

  • chorion frondosum increase in villi and create placenta for exchange
  • amnion and chorion fuse to make the amniochorionic membrane
• chorion laeve opposite the fetus is smooth and fuses with the uterine wall
• circulation in placenta

  • maternal into intervillous lakes
  • chorionic villi grow into lakes
  • blood flow from embryonic heart to capillaries, via umbilical arteries
  • fetal blood has higher affinity for oxygen
  • fetal and maternal is separated by syncytiotrophoblast
• placenta function

  • protection
  • gas exchange
  • nutrition
  • waste exchange
  • hormone production
• placental growth more than fetal in 1st trimester
• mother Rh- and father Rh+, fetus is Rh+, can lead to haemolytic disease
• 0-4 weeks problems

  • low placental hormone levels
  • genetic problems, cells don't replicate/survive
  • cell adhesion issues (twinning etc)
• caudal dysgenesis 


  lack of caudal mesoderm (associated with maternal diabetes)
• situs inversus

  • reversal of internal organs
• situs ambiguous

  • partial malrotation
• sacrococcygeal teratoma 


  origins in primitive streak, growth of tumour from tissue
• heart development

  • starts as cardiac tube
  • swellsand loops to form structure
  • growth is areas leads to separation into 4 chambers