Small babies Flashcards
How does growth occur in the embryonic period of development?
Absolute growth of embryo is minimal but morphogenesis of the body shape and development of all the organs begin in this stage; majority of growth occurs in the placenta. This occurs via action of IGF-2 hormone.
What is the mechanism of growth at 0-20 weeks gestation?
Hyperplasia which occurs via cleavage to increase cell number
How does growth occur in the foetal period of development?
Accelerated growth and weight gain. In the early foetal period, weight gain occurs due to protein deposition. In the late foetal period, weight gain occurs due to fat deposition. This occurs via action of IGF-1 hormone.
What is the mechanism of growth at 20-28 weeks?
Combination of hyperplasia via cleavage and hypertrophy of existing and developing structures.
What is the mechanism of growth at 28 weeks-term?
Hypertrophy of present structures such as the organs.
What are the different methods for dating pregnancy?
Crown-rump length, symphysis-fundal height, head circumference, femur length
What is used to determine gestational age before 24 weeks?
Crown-rump length- this the length of the foetus from head to bottom only used between 7-13 weeks in first trimester.
From 13 weeks: Head circumference and femur length that can be used to term.
How many ultrasounds do pregnant women receive in a standard pregnancy?
2 ultrasounds
One at 12 weeks to rule out ectopic pregnancy and number of foetus
One at 20 weeks to assess foetal growth and anomaly and view the fully formed heart chambers.
What is the CRL at 9 weeks?
5cm
What is the CRL at 38 weeks?
36 cm
How is foetal age estimated?
LMP (LAST MENSTRUAL PERIOD) which can be inaccurate
Abdominal circumference and femur length for detecting anomalies
Ideally use developmental criteria for accurate estimation
How is foetal wellbeing assessed in pregnancy?
Foetal movement, obstetric/ultrasound scan, biochemical tests and measurement of uterine expansion from symphysis-fundal height
What are the biochemical tests?
Levels f
hCG: important in first trimester
human placental lactogen: for metabolic regulation of foetal insulin sensitivity
Oestriol
A-fetoprotein
What is oestriol?
Pregnancy form of oestrogen which is important for triggering the development of the organs in the foetus.
What is a-fetoprotein?
Produced by embryonic hepatocytes which transport bilrubin, drugs and heavy metal ions in foetal blood circulation. It has a poor predictive value for low foetal growth and is expensive.
What is the issue with symphysis-fundal height?
Unreliable for detecting intrauterine growth restriction but can track uterine expansion to gauge foetal growth and is cheap and easy.
How does body proportion of the foetus change in pregnancy?
Head makes up the majority of CRL in early pregnancy, and proportions change as there is more accelerated lower limb and body length growth.
Why is nutrition important in pregnancy?
To support foetal development, which is reliant on maternal stores from the moment of conception. Malnutrition not only causes issues in utero, such as intrauterine growth restriction (both symmetrical and asymmetrical) but also lead to increased incidence of chronic disease in adulthood.
What is the Barker hypothesis?
Foetal responses to inadequate nutrition due to maternal factors or the placenta will increase the likelihood of chronic disease in adulthood.
What are the important hormones for foetal growth?
Insulin
IGF-1
IGF-2
Leptin
Epidermal growth factor and Transforming growth factor-alpha
What is the role of insulin in foetal growth?
Maternal insulin which cannot cross placenta but acts on placental receptors to stimulates the uptake of glucose in the foetus; foetal pancreas can also produce insulin.
This will increase foetal mass and create glycogen stores to be utilised during maximum demand in late gestation.
What is IGF-1?t
Insulin-like growth factor 1 which IS released via action of growth hormones to promote bone and tissue development. It increases the sensitivity of the cells to insulin and action of protein synthesis and fat deposition for we
When are IGF-1 levels most dominant?
Nutrient dependent and act primarily in the second and third trimester
What is IGF-2?
Insulin-like growth factor 2 which regulates foetal development
When are IGF-2 levels most dominant?
Nutrient independent and act primarily in the 1st trimester for morphogenesis.
What is leptin in foetal development?
Cytokine produced by the placenta which is important for foetal growth.