A 32-year-old G3P20L2 presents to the obstetrician’s office for a routine OB visit at 30 weeks. She has had no complications during the pregnancy and has had regular prenatal care. Her gestational age is confirmed with a first-trimester sonogram. During the routine OB visit, the fundal height measures 35 cm. All of the following can explain the size-date discrepancy except

**Core Concept**
Size-date discrepancy in pregnancy refers to a mismatch between the expected fetal size based on gestational age and the actual fetal size measured by fundal height or ultrasound. This discrepancy can be due to various factors, including fetal growth restriction, macrosomia, multiple gestations, or errors in dating the pregnancy.

**Why the Correct Answer is Right**
In a normal pregnancy, the fundal height increases by approximately 1-2 cm per week. A size-date discrepancy can be due to fetal growth restriction, where the fetus fails to grow at the expected rate, resulting in a smaller-than-expected size for the gestational age. In this case, the fundal height of 35 cm at 30 weeks is significantly larger than expected, suggesting macrosomia. Other possible causes include multiple gestations, where the fundal height may be larger than expected due to the presence of multiple fetuses, or errors in dating the pregnancy.

**Why Each Wrong Option is Incorrect**
**Option A:** Fetal growth restriction is incorrect because it would result in a smaller-than-expected size for the gestational age, not a larger size.
**Option B:** Multiple gestations is incorrect because it would result in a larger-than-expected size for the gestational age, but it would also be expected to have a higher fundal height than a singleton pregnancy.
**Option C:** Errors in dating the pregnancy is incorrect because it would result in a size-date discrepancy in the opposite direction (i.e., a smaller-than-expected size for the gestational age).

**Clinical Pearl / High-Yield Fact**
When evaluating a size-date discrepancy, it is essential to consider multiple factors, including the patient's medical history, the presence of any medical conditions, and the results of ultrasound measurements. A careful evaluation can help identify the underlying cause and guide management.

**Correct Answer: A. Fetal growth restriction.**

✓ Correct Answer: A. The 5-cm difference is within the error for fundal height measurements