Impact of the Number and Quality of Embryos Transferred in Multiple and Single Pregnancies

To investigate the relation between maternal age and embryo quality in choosing how many embryos should be transferred to obtain high pregnancy rates with minimal risk of multiple gestations.

Cross-sectional study, with secondary data analysis, including infertile couples undergoing Intracytoplasmic Sperm Injection, between 2005-2013, in the Assisted Fertilization Center - Fertility. The data was analyzed using the SPSS 16.0, in a descriptive and bivariate way using the chi-square test, P <0.05. Approved by the CEP UNISUL.

54.8% of pregnancies occurred with women ≤ 35 years. The prevalence of single pregnancy was 2.42 times the multiple pregnancies and no significant increase in multiplicity in the transfer of 3 or 4 embryos. The percentage of positive pregnancies was prevalent in the age group ≤ 35 years, regardless of embryo quality. Regardless of age, the greater the number of high quality transferred embryos, the higher the multiplicity. This was not observed with low-quality embryos. With high quality embryos, the prevalence of positive pregnancies in middle age women was 9% lower when compared to those aged ≤ 35 years, with a P = 0,310. With low-quality embryos, the prevalence of positive pregnancy in this age group was 39% lower when compared to those aged ≤ 35 years, with a P < 0.01.

The greater the number of high quality transferred embryos, the higher the multiplicity. However, this relationship is not true for low quality embryos. When only high quality embryos are transferred, the patients with intermediate age have similar pregnancy results to those from younger patients. Already with low-quality embryos, this same age group presents similar pregnancy results to older patients.