What is the main reason a nurse advises a primigravida to wait until 15 weeks gestation for amniocentesis?

Waiting until 15 weeks gestation for amniocentesis is primarily related to the availability of sufficient amniotic fluid for accurate sampling. At this stage of pregnancy, adequate amounts of amniotic fluid are present, which is essential for the procedure to be performed safely and effectively. If amniocentesis is conducted too early, there might not be sufficient fluid to retrieve the necessary samples, which can lead to a less accurate or inconclusive result.

While fetal development is a consideration in different contexts, the critical factor for amniocentesis specifically relates to the volume of amniotic fluid available. This ensures that the procedure can yield reliable results for the various tests conducted, including genetic testing and assessments of fetal health. Therefore, the guidance provided by the nurse is sound and reflects the clinical practices surrounding the timing of this important diagnostic procedure.