Methods: Thirty-eight samples of the AFI in different pregnancy age were separated by the method of the cellulose acetate thin-layer electrophoresis and their relationship with the pregnancy age and the birth weight was also observed.

• 方法：采用醋酸纤维膜电泳法对38例不同孕周的羊水中淀粉酶同工酶进行分离，并对其孕周和出生体重关系进行观察。