**Core Concept**
Amniocentesis is a prenatal diagnostic procedure that involves withdrawing a sample of amniotic fluid for genetic analysis. The gestational age at which amniocentesis is performed is crucial to ensure accurate results and minimize complications.

**Why the Correct Answer is Right**
The most appropriate gestational age for performing amniocentesis is between 12-16 weeks of gestation. This timing allows for the optimal balance between the accuracy of chromosomal analysis and the risk of amniotic fluid leakage, fetal membrane rupture, or other complications. At 12-16 weeks, the amniotic fluid volume is sufficient to obtain a reliable sample, and the risks associated with the procedure are relatively low. Moreover, this gestational age provides sufficient time for the mother to make informed decisions regarding the pregnancy, including the option for termination, if necessary.

**Why Each Wrong Option is Incorrect**
**Option A:** Performing amniocentesis at 10-12 weeks may be too early, as the amniotic fluid volume may not be sufficient to obtain a reliable sample, potentially leading to inaccurate results.
**Option C:** Amniocentesis at 20-25 weeks may increase the risk of amniotic fluid leakage, fetal membrane rupture, or other complications, as the amniotic fluid volume decreases with advancing gestation.
**Option D:** Performing amniocentesis at 25-30 weeks may be too late, as the risks associated with the procedure increase with advancing gestation, and the accuracy of chromosomal analysis may decrease due to changes in amniotic fluid composition.

**Clinical Pearl / High-Yield Fact**
A crucial aspect of amniocentesis is the importance of ensuring that the procedure is performed by an experienced practitioner in a sterile environment to minimize the risk of complications. Additionally, the mother should be counseled on the risks and benefits of the procedure and the potential implications of the test results.

**✓ Correct Answer: B. 12-16 weeks. This gestational age provides the optimal balance between accuracy and safety for amniocentesis.**