Association between spontaneous abortion and chromosomal abnormalities of products of conception from spontaneous and ART-conceived pregnancies

Abstract

Objectives: Chromosomal abnormalities are the most common cause of spontaneous abortion (SA). This study aims to analyze the association between SA and chromosomal abnormalities in products of conception, and to compare the impact of different pregnancy modes and different numbers of previous abortions on chromosomal abnormalities, providing clinical consulting references.

Methods: A total of 1 345 SA patients treated at the Affiliated Women's Hospital of Jiangnan University (Wuxi Maternity and Child Health Care Hospital) between January 2019 and December 2023 were enrolled. According to the mode of conception, patients were divided into 2 groups: a spontaneous pregnancy group (S group, n=1242) and an assisted reproductive technology (ART)-conceived group (ART group, n=103). Based on the number of miscarriages, the S group was further subdivided into a spontaneous sporadic abortion group (S-1 group, n=780) and a spontaneous recurrent abortion group (S-2 group, n=462); the ART group was subdivided into an ART sporadic abortion group (ART-1 group, n=68) and an ART recurrent abortion group (ART-2 group, n=35). Chromosomal microarray analysis (CMA) was performed on products of conception.

Results: The incidence of numerical chromosomal abnormalities was 56.79% (443/780) in the S-1 group and 52.38% (242/462) in the S-2 group, while the incidence of structural abnormalities was 4.36% (34/780) and 7.36% (34/462), respectively. There was a statistically significant difference in structural abnormalities between the 2 groups (P<0.05). Among the spontaneous pregnancy SA cases, the incidence of numerical abnormalities decreased with increasing numbers of miscarriages, and was significantly lower in the group with ≥4 miscarriages compared to those with 1 or 2 miscarriages (both P<0.05). The incidence of structural abnormalities in groups with 1, 2, 3, and ≥4 miscarriages was 3.46%, 5.65%, 5.88%, and 4.35%, respectively, with no statistically significant differences among groups (all P>0.05). The incidence of pathogenic copy number variants (pCNVs) plus likely pathogenic copy number variants (LP-CNVs) gradually increases in the group with 1-3 miscarriages, and there was a statistically significant difference between the group with 1 miscarriage and the group with 2 miscarriages (P<0.05). In the ART group, the incidence of numerical abnormalities was 47.06% (32/68) in ART-1 and 37.14% (13/35) in ART-2, while structural abnormalities occurred in 2.94% (2/68) and 11.43% (4/35), respectively, with no significant differences between the groups (both P>0.05). There were no statistically significant differences in the incidence of numerical or structural abnormalities between the S-1 and ART-1 groups, or between the S-2 and ART-2 groups (all P>0.05).

Conclusions: Chromosomal numerical and structural abnormalities are common in SA patients from both spontaneous and ART-conceived pregnancies. Attention should be paid to patients with recurrent miscarriage in genetic investigation.

Keywords: assisted reproductive technology-conceived pregnancy; chromosomal abnormalities; chromosomal microarray analysis; copy number variants; spontaneous abortion; spontaneous pregnancy.