Normal amniotic fluid index by gestational week in a Chinese population. Central-South China Fetal Growth Study Group.

OBJECTIVE

To construct an ultrasonography-based gestation-specific amniotic fluid index (AFI) curve in a Chinese population.

METHODS

Routine obstetric ultrasonography examinations were performed in 5496 normal pregnancies (more than 95% first births) in five obstetric ultrasound laboratories in Central-South China from January 1, 1992, to December 31, 1993. A gestation-specific AFI curve was constructed and compared with previous studies.

RESULTS

The gestational ages of the patients included in this study ranged from 16 to 40 weeks. The gestation-specific AFI showed patterns similar to those observed previously, with the median being 72 mm at 16 weeks, increasing to 119 mm at 26 weeks, and then gradually declining to a median of 91 mm at 40 weeks. However, the absolute value of AFI in this Chinese population was consistently and substantially lower than values reported in previous studies in populations with mixed parities.

CONCLUSION

Different standards of AFI are needed for different populations.