Assessment of Gestational Age Flashcards
How is gestational age conventionally described?
Gestational age is described in days or weeks after the last menstrual period.
What is the typical difference between gestational age and post-conceptual age?
Gestational age is usually 2 weeks longer than post-conceptual age.
What is considered preterm birth?
Preterm birth is defined as birth before 37 completed weeks gestation, up until and including 36 weeks and six days.
What is the average duration of gestation in days and weeks?
The average duration of gestation is 280 days or 40 weeks.
What percentage of women deliver on the expected due date?
Only 4% of women actually deliver on the expected due date, which is typically at 40 weeks of gestation.
The World Health Organisation (WHO) categorises preterm birth according into:
- Extreme preterm: <28 weeks.
- Very preterm: 28–32 weeks.
- Moderate to Late preterm: 32– <37 weeks.
- Term: 37–<42 weeks Post term (=post dates): ≥42 weeks.
What is the gold standard for gestational assessment, particularly in early pregnancy?
Early ultrasound, typically performed before fourteen weeks, is the gold standard for gestational assessment.
How accurate is ultrasound between 14 and 22 weeks for gestational assessment?
Ultrasound between 14 and 22 weeks is accurate within 7–10 days for gestational assessment.
What are some other antenatal methods used for estimating gestational age?
Other methods include the date of last normal menstrual period (LMP), assessment of uterine size before 18 weeks, and the measurement of Symphysis-Fundal Height (SFH) from 18 weeks. However, these methods can be unreliable.
When to measure the SF
from 18 weeks
Is there a simple and reliable postnatal method for establishing a newborn infant’s gestational age?
No, unfortunately, there is no simple and reliable postnatal method for establishing a newborn infant’s gestational age.
What are some limitations of current methods for determining gestational age in newborns?
All current methods have limitations and wide confidence intervals.
How are measurements of anthropometry affected when determining gestational age in newborns?
Measurements of anthropometry, including weight, head circumference, body length, and foot length, are all affected by varying rates of intrauterine growth and weight gain
What is reported to be a reliable marker for gestational age between 27 and 34 weeks?
The regression of the anterior vascular capsule on the lens of the eye.
Is the regression of the anterior vascular capsule on the lens of the eye useful outside the age window of 27 to 34 weeks?
No, it is technically difficult and not useful outside that age window.
