Endo-Repro L26 The Fetus and its Preparations for birth: Flashcards
Pattern of fetal growth is: Determined by
Genome of fetus
Pattern of fetal growth is: Modulated by
Placenta Hormones Environment • Nutrition • Health Metabolic
Pattern of fetal growth is: Hormones
Glucocorticoids, insulin
Insulin-like growth factors (IGFs or sometomedins)
Thyroid hormones
Human placental lactogen
Growth Retardation → IUGR
Defined as birth weight that is more than two standard
Types of IUGR
Type 1 → symmetric
Type II → Asymmetric
Intermediate IUGR
Type 1 (symmetric IUGR )
Decreased growth potential ~20%
Type II (asymmetric) IUGR
Restricted growth ~ 70% cases
Intermediate IUGR
Combination of types I and II
The human placental interface →
Maternal and fetal circulations pass close to each other, but do not mingle, to facilitate the exchange of materials.
Transport Across the placenta types:
- Transported intact
- Partially consumed
- Metabolised
- Not Transported
The Oxyhaemoglobin Dissociation Curve and the Bohr Effect →
The oxygen–hemoglobin dissociation curve plots the proportion of haemoglobin in its saturated form on the vertical axis against the prevailing oxygen tension on the horizontal axis.
Rightward shift → decreased affinity
- This makes it more difficult for haemoglobin to bind to oxygen (requiring a higher partial pressure of oxygen to achieve the same oxygen saturation)
- It makes it easier for the haemoglobin to release oxygen bound to it.
- The effect of this rightward shift of the curve increases the partial pressure of oxygen in the tissues when it is most needed, such as during exercise, or haemorrhagic shock.
The Double Bohr Effect:
- Fetal demand for oxygen regulates fetal oxygenation.
* Increased ph leads to a left shift of curve and an increased affinity for oxygen uptake.
Fetus capacity for gluconeogenesis
Little
Glucose supply
Maternal
Maternal glucose levels depend on
Nutrition
Endocrine control mechanisms
Early pregnancy Glucose and Carbohydrates:
Progesterone:
- Increases maternal appetite
- Builds fat stores
Late pregnancy Glucose and Carbohydrates:
Maternal tissues insulin insensitive:
- More glucose available to fetus
- Diabetes mellitus may develop in mother
Glucose storage provides for
The metabolic neds of the newborn baby until feeding begins
Glycogen is stored
In the liver and cardiac muscle
Glycogen and Fat: Regulated by
Fetal adrenal cortex
Which organ has no glycogen stores
The brain
What regulates fetal fat stores
Insulin
White fat stores
Fatty acids
Brown fat
Heat generation (Nonshivering thermogenesis)
Brown fat plays a crucial role in
Maintaining body temperature of the newborn baby after birth
Brown fat location
Head, neck, back and chest
White fat location
Lower back and buttocks
Amino acids
No increase in materal protein intake
Progesterone increases maternal metabolism efficiency
Fatty acids
Mother accumulates lipids in early pregnancy
Placental transfer and fetal synthesis meet fetal demands
Salt and water
Oestrogen and progesterone stimulate maternal retention
Water exchanges at placenta and non-placental chorion
Iron
Fetal blood has a 2-3 times higher concentration of iron
Maternal iron absorption is enhance
Calcium
Fetal ossification demands much calcium from mother
Maternal absorption of calcium is more efficient
Fetal development requires
Folic acid and vitamin B12
Folic acid
Amino acid metabolism
Vitamin B12
Made by
Provided by
Fatty acid and amino acid metabolism
Provided at expense of maternal stores
Recommended weight gain
11.5-16 kg
Weight gain from Intrauterine contents:
Fetus → 3.3 kg
Placenta → 0.7 kg
Amniotic fluid → 1.0kg
Weight gain maternal contribution
Uterus → 0.7 kg
Blood → 1.3 kg
Breasts →2.0 kg
Adipose tissue and interstitial fluid → 5.0 kg
Response of the Mother to Pregnancy: Cardiovascular changes
Blood volume expands
Cardiac output increases
Response of the Mother to Pregnancy: Respiratory system
Alveolar ventilation increases
Response of the Mother to Pregnancy: Nutrition
Maternal diet should be supplemented with iron and folic acid
