Background: Fundal height measurement is a standard clinical assessment tool used in prenatal care. This study compared the fundal heights growth curves of two ethnically distinct groups of pregnant women. We were motivated by our clinical experience with one group where fundal heights seemed 'small for date' and by the reluctance of this group to undergo further testing, especially ultrasound.
Methods: A prospective cohort study compared the fundal heights growth curve of 48 Caucasian and 40 Hmong women from two clinics in central Wisconsin (USA).
Results: Southeast Asian Hmong women were found to have a slower rate of fundal height growth than Caucasian women (significantly different average slopes of .88 vs. .95, respectively). An expectation of linear growth appeared more valid for Caucasian than Hmong women. At 40 weeks, regression based estimates overestimated the Caucasian sample by 1.3 weeks and the Hmong sample by 2.7 weeks. ANCOVA procedures remained significant while controlling for group differences in height. Fundal height measurements were moderately predictive of birth weight for the Hmong sample but not the Caucasian sample (multiple r=.39).
Conclusions: Considerable differences emerged between fundal height measures for the Hmong and Caucasian samples. The improved ability to differentiate groups following control of variance due to height as well as the ability to predict birth weight from fundal height curve in the Hmong group argue for value of normative development using more homogeneous groups. Clinicians should consider the applicability of fundal height norms to their clinical populations and may be able to have more confidence in using fundal height as an evaluative tool with more appropriate norms.