Estimated fetal weight
Abbreviation: EFW
Estimated fetal weight (EFW) is a calculation your doctor makes using measurements taken during an ultrasound scan, typically the baby's head size, abdominal circumference, and femur length. A formula combines these figures to produce a weight estimate in grams. EFW is used to monitor whether your baby is growing within a healthy range for its gestational age. Babies measuring below the 10th percentile may be flagged as small for gestational age, while those above the 90th percentile may prompt additional monitoring. Accuracy typically falls within a margin of 10 to 20 percent, so the number is a guide rather than a precise reading.
What This Means for You
Understanding Estimated fetal weight is an important part of your second/third trimester journey. During pregnancy, your care team will use this term regularly. Being familiar with it means you can ask better questions and feel more confident at your antenatal appointments.
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Do not be alarmed if the estimated weight differs from your newborn's actual birth weight. Larger margins of error are common in the third trimester when babies are more tightly packed in the womb.
Related Terms
Source: https://www.acog.org/womens-health/faqs/how-your-fetus-grows-during-pregnancy
Always consult your healthcare provider for personalised advice.
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