Fundal Height of 16 cm at 16 Weeks Gestation
A fundal height measurement of 16 cm at 16 weeks gestation is normal and follows the expected correlation where fundal height in centimeters approximately equals gestational age in weeks during the mid-second trimester.
Normal Fundal Height Parameters
- Between 20-31 weeks gestation, fundal height in centimeters should equal weeks of gestation, with a confidence interval of ±3 weeks 1
- At 16 weeks gestation specifically, the fundal height measurement of 16 cm falls within expected parameters for normal fetal growth 1
- The fundus typically reaches the umbilicus at approximately 16.6 ± 0.9 weeks gestation 1
Clinical Context and Accuracy
- Carefully derived obstetric estimates using fundal height measurements can be reliable for assessing gestational age, with a standard deviation of approximately 11.4 days when combined with other clinical findings 1
- This measurement technique has accuracy approaching that of reliable menstrual history (SD: 10.2 days) 1
Important Caveats
Common pitfall: Gestational age may be overestimated by assuming the fundus reaches the umbilicus at exactly 20 weeks, when it actually occurs closer to 16-17 weeks 1
- Serial measurements are more valuable than a single measurement for assessing appropriate fetal growth 1
- If there are concerns about fetal size discrepancies, ultrasound biometry should be performed at intervals of no less than 2 weeks, with 3-4 week intervals being more reliable due to inherent measurement error 2
When to Consider Further Evaluation
- If subsequent measurements deviate significantly from the expected centimeter-to-week correlation (beyond ±3 weeks), ultrasound evaluation should be considered 1
- For pregnancies requiring growth surveillance, ultrasound remains the preferred method for precise fetal weight estimation and characterization of growth patterns 3