A comparative cytogenetic study of miscarriages after IVF and natural conception in women aged under and over 35 years.

Purpose: To compare the frequency and the spectrum of karyotype abnormality in the first trimester miscarriages in women aged under and over 35 years, who conceived naturally (NC) and who conceived through in vitro fertilization (IVF).

Methods: Comparative analysis of cytogenetic data obtained by karyotyping of miscarriages in patients who conceived naturally, and who conceived through IVF. Patients were subcategorized by their age: <35 years (NC, n = 173; IVF, n = 108) and ≥ 35 years (NC, n = 107; IVF, n = 111).

Results: A total of 499 miscarriage karyotypes was analyzed. The spectrum and the relative proportions of different cytogenetic categories in karyotypically abnormal miscarriages differed neither between the NC and IVF patients aged <35 years, nor between the NC and IVF patients aged ≥ 35 years. In the patients aged <35 years, the incidence of abnormal miscarriage karyotype was lower in the IVF group (37.04 % vs 62.43%). In the patients aged ≥ 35 years, the incidence of miscarriages with cytogenetic pathology did not differ between the NC and the IVF group (75.70 % vs 58.56%). The lowest frequency of karyotypically abnormal miscarriages (29.82%) was detected in the young IVF-treated patients at <7 weeks of gestation.

Conclusions: IVF does not increase the risk of a pregnancy loss because of abnormal embryonic karyotype, nor does it increase the preponderance for any specific type of cytogenetic abnormality in both patients aged under and over 35 years. In young IVF-treated women early pregnancy loss is generally caused by non-cytogenetic factors. Identification of a cytogenetically normal spontaneous abortion is clinically significant and reinforces the importance of developing an appropriate diagnosis and treatment strategies for IVF patients in order to reduce the risk of euploid pregnancy loss.