Pregnancy & Labour Flashcards

Question

Reasons for Altered joints?

Answer 1

Changes in pelvis to make connections more flexible to permit child-birth.

Answer 2

o Production of factors – supress the maternal immune system from the utero-placental interface. This results in a reduction of Th1 responses and increased Th2 responses. o Placenta cells expresses unusual HLA – placental HLA are almost invariant (HLA-G has 5 known sequence variants – normal HLA-A and others have millions of variants) and very simple. This is thought to identify the tissue as human but due to its simplicity, no other information is given. HLA-G can also supress some leucocytes and down-regulate maternal immune responses.

Answer 3

o Conceptus – everything resulting from the fertilised egg. o Embryo – the baby up to week 8 of development. o Foetus – the baby for the rest of pregnancy. o Infant – applied after delivery typically.

Answer 4

 Again, remember that timings used to discuss embryology are usually from point of fertilisation, 2 weeks after LMP timings used in timings of pregnancy – the embryology timings are PF – Post-Fertilisation.

Answer 5

o First trimester – 50g. o Second trimester – 1050g – viable at 500-820g stage (21-24 weeks). o Third trimester – 2100g.

Answer 6

o Too few sex chromosomes – Turner’s syndrome – 45 X0. o Too many sex chromosomes – Klienfelter’s syndrome – 47 XXX, 47 XYY, etc. o Too few autosomes – non-viability, as does 45 Y0 [no x chromosome – one is essential] o Too many autosomes – Downs Syndrome – trisomy 21.

Answer 7

 Most risks to the pregnancy occur in the first trimester of pregnancy. The main risks associated with pregnancy in the 3rd trimester is to do with the birth: o There are 4 main organs (lungs, digestive system, immune system and brain) that have limited use in utero so late development is logical but problems developing here become apparent at birth.  This also may cause problems with pre-term birth.

Answer 8

Separation between maternal and fetal vascular system Exchange nutrients and waste products Biosynthesis Immunoregulation of whole of pregnancy [ensures no rejection of conceptus] Connection: placenta must anchor the pregnancy in place SEBIC

Answer 9

 Primary subunit is the placental villus that has the branches. o This provides a large surface area for exchange between the maternal and foetal vascular systems.  Note that the veins contain oxygenated blood and the arteries contain deoxygenated blood as the placenta carries out a parallel function to the lungs during pregnancy.  Note the separation of the maternal and foetal systems despite being near.  Cotyledons – the maternal surface of the placenta is sub-divided into cotyledons. Each contains one or more villi. (The gaps between cotyledon contains maternal tissue = decidua)

Answer 10

Approx. 9 days PF, the conceptus is completely implanted in the maternal endometrium. 1. IMPLANTATION of conceptus into endometrial epithelium. 2. Trophoblast layer of the conceptus forms 2 layers → cytotrophoblast (CTB, inner) and syncytiotrophoblast (STB, outer layer) - Note: Placenta originates from the cytotrophoblasts layer. 3. STB sends out PROJECTIONS to embed onto the endometrium + LACUNAE → form in STB gets filled with maternal blood. 4. CTB expansion into STB → PRIMARY CHORIONIC VILLI 5. Mesoderm line (fill) these villi → SECONDARY CHORIONIC VILLI. 6. Embryonic blood vessels form in the mesoderm → TERTIARY CHORIONIC VILLI [Cytotrophoblasts proliferate into the syncytium to form a columnar structure which becomes a villous structure] 7. CTB cells from the villi grow towards the decidua (maternal tissue between cotyledon) and form a CTB SHELL . This has plugs. 8. ~6th week → the villi reach maternal spiral arteries → CTB invade the spiral arteries → SPIRAL ARTERY REMODELLING i.e. arteries become wide bore = greater exchange of nutrients 9. ~10-12th week → CTB plugs breakdown and placenta exposed to full maternal blood flow. [note: decidual gland hypertrophy supplies nutrients during 1st trimester - not maternal blood - maternal blood when plugs breakdown that block spinal arteries] - The source of the nutrients (glands: histotrophic) rather than maternal blood (haemotrophic) is different

Answer 11

If the placenta is not anchored properly, the increased pressure as it is exposed to the maternal blood supply can lead to a detach and a miscarriage.

Answer 12

 The remodelling converts the narrow bore spiral vessels into wide-bore vessels to transport more volumes of blood. o The ctb cells replace the vascular endothelium and VSMCs which is important as it means the vessels here cannot respond to vasoconstrictors.  The placenta has no nerves so can be cut without harm

Answer 13

 Placenta regulates its own growth/development through autocrine functions.  The maternal decidua mainly seems to restrain (modulate) placental growth/development so the placenta is optimal both for the baby and mother.

Answer 14

Most risks to the mother lie in delivery and labour. Risks: o Remodelling of the spiral arteries means that vessels can lose relatively large amounts of blood after delivery – this should be limited by contractions of the uterus after the placenta has been delivered. o Placenta must be checked carefully to make sure all has been delivered as it is quite inflexible and any left in the uterus may lead to ineffective uterine contractions.

Answer 15

o Most severe risk is in defects in the gametes – chromosome irregularities. - Loss of any autosome is not compatible with life  miscarriage. - Changes in sex chromosomes is generally less severe (loss is more serious than gain). • Turners is a loss of a sex chromosome and leads to infertility. o Infants born before 32w GA are at the greatest risk due to incomplete development of the 4 organs (brain, lungs, digestive and immune systems)

Answer 16

o Most serious problem is incomplete anchorage in the 1st trimester. Possibly due to:  Developmental problems.  Detachment in the late 1st trimester. Note: Placental delivery after baby delivery is importnat.

Answer 17

 Stillbirth – death of the infant within the uterus, so that it is delivered without signs of life. o Some definitions include the viability limit (23w) so any dead births before this are miscarriages and any after this are stillbirths.

Answer 18

 Detection – via monitoring of foetal wellbeing: o Ultrasound – monitor foetal movements. o Foetal blood flow assessment – Doppler ultrasound.