**Question:** At 15 weeks of gestation, increased alpha fetoprotein in amniotic fluid is seen in:

**Core Concept:**
Alpha fetoprotein (AFP) is a protein produced by the fetus during pregnancy, particularly in the liver and yolk sac. In normal pregnancy, AFP levels in amniotic fluid gradually decrease as gestation progresses, reflecting normal fetal development and growth. However, some abnormal conditions can lead to elevated AFP levels in amniotic fluid.

**Why the Correct Answer is Right:**
In the context of 15 weeks of gestation, increased AFP levels in amniotic fluid are typically seen in cases of certain fetal abnormalities or malformations. The liver is the primary source of AFP production in the fetus. Anorexia, malabsorption, or impaired liver function can lead to decreased AFP production and thus decreased AFP levels in amniotic fluid. However, at 15 weeks, these conditions are less likely, and the primary cause for increased AFP levels is typically due to fetal liver dysfunction or malformation.

**Why Each Wrong Option is Incorrect:**
A. This option is incorrect because normal AFP levels are expected at this stage of pregnancy.
B. This option is incorrect as AFP production is primarily fetal and not maternal.
C. Increased AFP levels at 15 weeks are more commonly seen in cases of neural tube defects (e.g., anencephaly), not only chromosomal abnormalities.
D. This option is incorrect as the primary cause of increased AFP levels is fetal liver dysfunction or malformation, not maternal conditions.

**Clinical Pearl:**
Increased AFP levels in amniotic fluid at 15 weeks of gestation should raise suspicion for cases of fetal liver dysfunction or malformation (e.g., hepatoblastoma, hypospadias, or other liver malformations). Further evaluation is necessary, including ultrasound, amniocentesis, or cordocentesis. In case of increased AFP levels, it is crucial to evaluate for potential fetal abnormalities to ensure appropriate prenatal management and interventions.