There are no official guidelines to assist in answering this question. I will search for relevant research papers instead.
From the Research
Prenatal Ultrasound Frequency for Suspected Macrosomia
- The recommended frequency for prenatal ultrasound in a fetus with suspected macrosomia is not explicitly stated in the provided studies.
- However, the studies suggest that a single ultrasound examination at late gestation, close to birth, is the simplest method currently available to predict large-for-gestational-age (LGA) and macrosomia 1.
- Another study proposes a two-stage strategy for identifying pregnancies with a LGA fetus, which includes routine fetal biometry at 36 weeks' gestation and another scan at 38 weeks if the estimated fetal weight is above the 70th percentile 2.
- The American College of Obstetricians and Gynecologists (ACOG) recommends that women with a suspected large-for-gestational-age fetus should be offered ultrasound estimation of fetal weight at 36-38 weeks of gestation, but the frequency of ultrasound examinations is not specified.
- A study published in 2020 found that large-for-gestational-age diagnosed during second-trimester anatomy ultrasound is associated with the development of gestational diabetes mellitus and large-for-gestational-age at birth, but it does not provide guidance on the frequency of prenatal ultrasound 3.
- A 2025 study found that late third-trimester ultrasound estimation of fetal weight has a good ability to identify and predict large-for-gestational-age at birth, but it does not specify the optimal frequency of ultrasound examinations 4.
Key Findings
- A single ultrasound examination at late gestation is sufficient to predict LGA and macrosomia 1.
- Routine fetal biometry at 36 weeks' gestation can be used as a screening test for fetal macrosomia, and another scan at 38 weeks can be used to confirm the diagnosis 2.
- The frequency of prenatal ultrasound examinations for suspected macrosomia is not explicitly stated in the provided studies.
- Ultrasound estimation of fetal weight at 36-38 weeks of gestation is recommended for women with a suspected large-for-gestational-age fetus, but the frequency of ultrasound examinations is not specified 4, 3.