Estimate of genetic variants using CNV‐Seq for fetuses with oligohydramnios or polyhydramnios

BACKGROUND: Oligohydramnios or polyhydramnios, is associated with chromosomal aberrations, particularly aneuploidy. However, its correlation with copy number variation (CNV) remains unclear. METHODS: We retrospectively analyzed 428 cases with an abnormal level of amniotic fluid, comprising of 139 cases of single ultrasound findings (SU group) and 289 cases of multiple ultrasound findings (MU group), by CNV sequencing (CNV‐Seq) and followed their pregnancy outcomes. RESULTS: The overall detection rate of clinically significant findings was 8%, with 5% in the SU group and 11% in MU group. Besides, 18 microdeletion/microduplication syndromes were detected, with the highest rate of renal cysts and diabetes syndrome (22%, 4/18). Also, the rate of termination of pregnancy in MU group was much higher than that in the SU group (29% vs. 10%, ***p < 0.001), and in the MU‐oligohydramnios subgroup, it was the highest (34%), regardless of cases with chromosomal anomaly and lost to follow‐up. CONCLUSION: Our results showed that the abnormal level of amniotic fluid, especially combined with other ultrasound abnormalities, is closely related to chromosomal abnormalities and genetic CNVs. CNV‐Seq may be useful in investigating pregnancies with an abnormal amniotic fluid level.