In Utero
Placenta
fetomaternal organ
begins with implantation of blastocyst
ends with delivery in 3rd stage of labor
Provides
nutrition, gas exchange, waste removal, a source of hematopoietic stem cells, endocrine and immune support
Basal plate
Circulation:
Umbilical: placental
Systemic:
Vitelline: yolk sac > later portal
Ectoderm > Skin (Epidermis), Enamel, brain
Mesoderm > Bone, Cartilage, Fat, Muscle (Cardiac, skeletal), renal tubule cell, Blood, Reprod, some GUT
Endoderm > GIT, Resp, Endo, epithelium of Middle ear (inc eustachian) some GUT
AFP ? foetal albumin ?different interaction with hormones thus protecting foetus from maternal levels
High in germ cell tumours, hepatocellular carcinoma, ataxia telangiectasia
high maternal level for gestation in neural tube defects
Low maternal level for gestational age in down syndrome
Amniotic fluid
Adequate amniotic fluid is required for normal foetal movement and growth, and as a cushion for foetus and cord
Oligohydramnios (less than normal for gestation)
- 7% > Foetal compression syndrome (↑uterine pressure, ↓foetal movement): limb positional/craniofacial deformities
- cord compression > death
- Pulmonary hypoplasia
Foetal swallowing, urine production and lung fluid dictate amniotic fluid level
Also intramembranous absorption (across amnion into foetal circulation) can limit polyhydramnios
IUGR > diversion of blood from kidneys > reduced urine output > oligohydramnios
Renal agenesis > Oligo
PPROM > Oligo
oesophageal/duodenal/jejunal atresia > polyhydramnios if not compensated for by IMAbsorp
Majority are idiopathic
Start of second trimester starts swallowing and passing urine
Cord prolapse = loop of cord into cervical canal prior to or with presenting part > cord compression