Fetal Age Assessment: Methods of Calculating Gestational Age

This article will focus on methods of determining fetal age, a crucial factor in monitoring and managing pregnancy.

Based on Ossification Points:

• Ossification points refer to the appearance of bone ossification centers in the fetal skeleton, which can be used to estimate gestational age.

• Among these points, the upper end of the tibia is the latest to appear during pregnancy.

Based on Amniocentesis:

• Amniocentesis is a procedure that involves extracting amniotic fluid for analysis to evaluate fetal health.

• This test can reveal the color of the amniotic fluid, reflecting the fetal condition. For example, blue amniotic fluid may indicate fetal distress, while reddish-brown amniotic fluid may be associated with fetal demise.

• However, amniocentesis cannot determine whether a pregnancy is premature or full-term.

Based on Ultrasound:

• Ultrasound is a non-invasive imaging technique commonly used to monitor pregnancy.

• Between 7-13 weeks of gestation, the crown-rump length of the fetus is used to assess gestational age.

• From 13-23 weeks of gestation, the biparietal diameter of the fetal head is a reliable indicator of gestational age.

Based on Epithelial Cell Examination in Amniotic Fluid:

• This test evaluates fetal maturity.

• Nile blue staining is used to stain the epithelial cells in amniotic fluid.

Based on Creatinine Levels in Amniotic Fluid:

• Creatinine levels in amniotic fluid increase with gestational age.

• At 36 weeks of gestation or beyond, creatinine levels in amniotic fluid are approximately 2mg%.

Based on Other Tests:

• Other tests may be employed to determine gestational age and assess fetal maturity.

• Lecithin/Sphingomyelin ratio > 2 is the most valuable indicator for diagnosing fetal maturity.

Note:

• These methods are merely reference points.

• Accurate gestational age determination requires the combination of multiple methods and evaluation by a qualified medical professional.

Conclusion:

This article has presented several common methods for determining gestational age. Understanding these methods can help you monitor your pregnancy effectively and proactively.