Embryonic Development in Relation to Maternal Age and Conception Probability

Abstract

Data regarding association between early embryo development and maternal age is limited and inconclusive. This study has two aims: to evaluate differences in the cleavage stage of embryos in young versus advanced maternal age (AMA) women. To compare the early embryonic development of embryos that result in pregnancy versus no pregnancy. A retrospective study of early embryonic development which was recorded and analyzed using time-lapse imaging was conducted. The kinetic markers of time to pronuclei fading (tPNf) and appearance of two to eight cells (t2-t8) were assessed. For embryos cultured to blastocyst, times to morula (tM), start of blastulation (tSB) cavitated, and expanded blastocyst (tB, tEB) were also recorded. A total of 2021 oocytes from 364 intracytoplasmic sperm injection (ICSI) cycles were evaluated, of which 1223 (60.5%) were derived from young patients and 798 (39.5%) from those of AMA. The mean time points to t3, t4, t5, t6, tSB, tB, and tEB were significantly shorter for embryos derived from younger women, as compared to older women (p < 0.05). Overall, women who conceived presented a faster embryonic development, for both age groups. The mean time points of t2 and t8 were significantly shorter in patients who conceived versus not conceived (p < 0.05). We concluded that older women's age is associated with delayed embryonic development. Embryos that yielded pregnancy cleaved faster compared to those which did not, in both age groups. Thus, when considering which embryo to transfer to women of AMA, selecting the faster-developing embryos may improve the chances of conception.

Keywords: Advanced maternal age; Embryo development; Intracytoplasmic sperm injection cycles; Morphokinetic parameters; Time-lapse imaging.