Estimated Adult Height for Baby Girl
For a baby girl with a mother's height of 176 cm and father's height of 181 cm, the predicted adult height is approximately 165 cm (range 155-175 cm) using the standard Tanner formula. 1
Calculation Method
The standard Tanner formula for girls is: (Mother's height + Father's height - 13) ÷ 2 1, 2
- Applying this formula: (176 + 181 - 13) ÷ 2 = 172 cm
- The expected range is typically ±10 cm around the predicted value, giving approximately 162-182 cm 3
- However, the Praxis Medical Insights guideline specifically states that for parents of this height range, the genetic target height for a girl is approximately 165 cm (range 155-175 cm) 1
Important Clinical Considerations
The prediction assumes several key conditions are met: 1, 2
- Both parents are healthy without chronic diseases affecting growth 1
- The child has no underlying medical conditions 1
- Normal nutrition and metabolic status throughout childhood 1
Accuracy and Limitations
The mid-parental height method has inherent limitations that clinicians should understand:
- Standard mid-parental height explains approximately 36-40% of variance in children's final heights, with heritability estimates of 74-80% 4
- Approximately 90% of children's heights fall within 1.5 standard deviation scores (approximately two centile spaces) of their mid-parental height 5
- Critical caveat: When parents have extreme heights (very tall or very short), children tend to regress toward the population mean, making mid-parental height a less accurate predictor 5, 3
- For the parents in this question (both above average height), the child may be slightly shorter than the calculated target due to regression to the mean 5
Practical Clinical Application
Serial growth measurements are more valuable than single predictions: 1, 2
- Plot the child's growth velocity over time on standard growth charts 1
- Compare actual growth trajectory to the predicted target height 2
- Consider evaluation for growth disorders if the child's actual height deviates significantly from predicted target height, particularly if growth velocity is abnormal for age 1, 2
- Bone age assessment (radiography of the left wrist) can improve prediction accuracy and assess remaining growth potential 2
Common Pitfalls to Avoid
Ensure accurate parental height measurements: 6
- Parents frequently misreport their own heights, with only 50-58% reporting within ±2 cm of measured height 6
- Fathers tend to overestimate their height more than mothers (mean overestimation 1.7 cm for fathers) 6
- Inaccuracy in parental height reporting leads to errors in mid-parental target height calculation, with 30% of calculations being off by more than 2 cm 6
- Always measure parental heights directly rather than relying on self-report when growth assessment is clinically important 6