Flashcards in Repro 9.2 Foetal Growth and Development Deck (60)
When does the foetal period begin and end?
Begins at the 8th week post conception and ends at birth
In general terms what happens during the foetal period?
Growth and maturation of systems laid down during the embryonic period to fit the individual for birth and postnatal life
What are the most important body systems for determining survival outside the uterus?
What is the embryonic period also known as?
Organogenetic period - intense morphogenesis and differentiation. Includes little weight gain. Absolute growth is very small except the placenta
What causes major weight gain during the foetal period?
Early foetal period - protein deposition
Late foetal period - adipose deposition
What are the potential reasons for a small neonate?
Intra-uterine growth retardation
What 3 broad categories may age of foetus be estimated by?
Duration of pregnancy
Syphysis - fundal height
How is the duration of pregnancy assessed?
Age since mothers last menstrual period (+2 weeks of fertilisation age)
Why is the duration of pregnancy prone to inaccuracy?
Irregular menstrual cycles
Mother may not be confident of last menstrual period date
How can the developmental criteria be assessed?
What is measured during ultrasound to assess development?
Biparietal diameter of head
How can age be assessed after delivery?
Weight and appearance
Why and when is crown-rump length measured?
7 - 13 weeks to date pregnancy and estimate EDD. Crown rump length increases rapidly in pre-embryonic, embryonic and early foetal periods so will give a good indication of age
What is biparietal diameter of the head?
Distance between parietal bones of the foetal skill (assessed in T2 and 3)
What are abdominal circumference and femur length used for?
Used with BPD for dating and growth monitoring
Also useful for anomaly detection
What is symphysis-fundal height?
Distance from the symphysis pubis to top of uterus
How is the symphysis-fundal height measured?
Can be measured with a tape measure and should relate to weeks (e.g. 20 weeks, 20cm although plateaus after 36 weeks)
Height of fundus can also be measured in relation to other structures e.g. umbilicus, xiphisternum
Where is the uterus palpable at week 12?
Above the pelvis
How is intrauterine/foetal growth restriction assessed?
A lag of 4cm or more of the fundal height
What sources can cause variability in estimation of foetal age?
Number of foetuses
Volume of amniotic fluid
Extent of engagement of the head
Postion of the foetus
What are the advantages of ultrasound?
Can be used in pregnancy to calculate age also location, number and viability
What is the purpose of the 20 week scan?
Assess foetal growth and anomalies
What is considered to be low, normal and high birth weight?
Low 4500g = macrosomia
What are the 4 phases of maturation of the lungs?
Canalicular (16-26 wks)
Terminal Sac (26 - term)
Alveolar period (late foetal to 8 years)
What development of the respiratory tract occurs in the embryonic period?
Bronchopulmonary tree forms
Respiratory diverticulum is separated from the oesophagus by the tracheoesophageal septum
What histological changes occur in the respiratory system in the pseudoglandular phase?
Duct system forms
Airways formed as far as terminal branches
What histological changes occur in the respiratory system in the canalicular phase?
Building from bronchioles, some terminal sacs begin to form at 24 wks
What histological changes occur in the respiratory system in the terminal sac phase?
Many primitive sacs form and some primitive alveoli
Differentiation of pneumocytes to type I and II
Surfactant formed from week 20
What histological changes occur in the respiratory system in the alveolar period?
Alveoli form (95% post-natally)