Based on multi-center clinical research resources, a large-scale prospective cohort study will be conduted to make a more accurate diagnosis and intervention plan of Non-immune fetal hydrops (NIFH), and then establish NIFH accurate treatment strategy which is suitable for China's national conditions.

1. Etiological study of Non-immune fetal hydrops(NIFH):

   1. Etiological study of NIFH in mid-pregnancy period;
   2. Etiological study of NIFH and hygroma colli in first trimester;
   3. Value assessment of technology for exome sequencing in diagnosis of NIFH;

2. The accuracy of NIFH intrauterine intervention and its effect assessment:

   1. Perinatal outcomes of NIFH ;
   2. The effect of intrauterine treatments.

Inclusion Criteria:

• Cases corresponding to diagnosis standards
• Willing to accept the regular follow-up

Exclusion Criteria:

• Immune hydrops fetalis
• Multiple pregnancy, except for twin-to-twin transfusion syndrome IV