Introduction
Recurrent pregnancy loss (RPL) is defined as two or more pregnancy
losses before 20 weeks with a 1-3% incidence rate from ESHRE in 2018
[1]. In addition to unexplained miscarriage accounting for 50% of
RPL [2], other factors, such as female age, uterine anomalies,
endocrine disturbances, autoimmune antibodies, thrombophilia and
chromosomal aberrations, are known risks of RPL[3]. Parental
chromosomal aberrant couples, called carriers, account for 2-4% of the
recurrent pregnancy loss population[4, 5]. Unbalanced gametes
generated from chromosomal aberrant parents are associated with RPL, but
no direct causal relationship has been proven between the parental
chromosome and RPL, because foetal chromosomal abnormalities of abortion
tissue are common not only in carriers but also in noncarriers[6,
7]. No consensus exists regarding the difference in pregnancy outcomes
between carriers and noncarriers with RPL to date. Additionally
preimplantation genetic diagnosis (PGD) has been performed increasingly
at several centres worldwide, and has been applied for patients with
chromosomal aberrations. Can PGD improve live birth rates compared with
natural conception or expectant management (NC or EM) in RPL carriers?
However, no evidence has substantiated the reproductive outcome benefit
of these carriers after EM or after PGD. Recurrent pregnancy loss with
abnormal chromosomes is a frustrating challenge for clinicians because
no convincing evidence of effective therapy exists for these patients.
The present study aimed to systematically analyse the best evidence from
the efficacy literature to illustrate these associative questions.