Objective: To obtain more information on interindividual variation in early fetal growth by using early fetal ultrasound parameters.
Design and subjects: Individual fetal growth was assessed prospectively in 109 pregnancies by serial ultrasound measurements of CRL and BPD. From the resulting biometry data, individual CRL and BPD growth curves for each fetus were constructed and compared.
Results: A high correlation was found between growth rate and the start of growth of CRL and BPD, r = 0.79 and r = 0.84, respectively.
Conclusion: The high correlation between growth rate and the start of growth of CRL and BPD might imply that a fetus with an impeded start of growth generally has a higher growth rate. This could be called an early pregnancy 'catch-up growth'. This interindividual variation of starting time and fetal growth rate may influence the assessment of gestational age in early pregnancy, if a CRL-curve obtained from cross-sectional measurements is used as a reference. BPD seems to be a more constant parameter with less variation in growth rate.