Original articleComparing early embryo morphokinetics with time-lapse microscopy in patients with low and normal ovarian response to ovarian stimulation
Introduction
Low ovarian reserve and an expected poor ovarian response to ovarian stimulation (OS) affects 9–24% of infertile women undergoing Assisted Reproductive Technologies (ART) primarily depending on the average female age of the infertile population [1]. Poor ovarian responders have lower Anti-Müllerian hormone (AMH) and number of aspirated oocytes as well as higher age compared to normal responders [2]. However, embryo developmental patterns in patients with low and normal ovarian reserve are scarcely described [3,4]. Specific mechanisms associated with age related follicular depletion are poorly understood [5,6], although different causes of low ovarian reserve have been identified: ovarian surgery, genetic defects, chemotherapy, radiotherapy, autoimmune disorders, single ovary, smoking and unexplained infertility [7,8].
In the era of time-lapse microscopy (TLM) and elective single embryo transfer (eSET), many studies have tried to define the best morphokinetic parameters for selection of the embryo with the highest implantation potency [[9], [10], [11]]. The selection of the best embryo is a challenge especially when the initial number of oocytes is low. It is evident that increasing number of aspirated oocytes is associated with higher live birth rates up to a certain level [[12], [13], [14], [15], [16], [17]]. A Chinese study involving 2455 ART cycles supports that in first in vitro fertilization (IVF) treatment patients with 6–10 or 11–15 aspirated oocytes have a better chance for a live birth compared to patients with 0–5 or >15 aspirated oocytes [18]. Additionally, there was a negative association between age and the oocyte pool as well as with the fertilization rate and the number of aspirated oocytes. Information retrieved from The Swedish National Quality Registry of Assisted Reproduction (Q-IVF) including 77,956 fresh IVF cycles in the period 2007–2013 demonstrates that live birth rate increases per cycle when up to 11 oocytes are aspirated [13]. On the other hand no statistical significant difference was identified regarding the blastulation rates, aneuploidy rates and live birth rates when women less than 38 years old with low ovarian response were compared with peer-to-peer women with normal ovarian response [19].
However, it remains unknown whether morphokinetic parameters and cleavage stage patterns differ in embryos from patients with a low ovarian response compared to embryos from women with a normal ovarian response. Further it is unknown if the same morphokinetic TLM parameters can be applied for the prediction of blastocyst formation and implantation rates in both groups. A variety of moprhokinetic parameters have been proposed for being crucial predictors for blastocyst formation and implantation rates: time to PN fading [20,21], time to 2 cell stage (t2), 3 cell stage (t3), 5 cell stage (t5), 8 cell stage (t8) as well as asynchrony from 2 to 3 cells, 5 to 8 cells, multinucleation, reverse cleavage and direct unequal cleavages [[22], [23], [24], [25], [26], [27], [28], [29]]. However, the first cell divisions from 2-to-8 cells and direct unequal cleavages have the most promising predictable value for blastocyst formation and implantation [9,[30], [31], [32], [33], [34]].
Our aim is to study early embryo TLM parameters and cleavage stage patterns from patients with a low ovarian response compared with embryos from patients with a normal ovarian response using the EmbryoScope time lapse system.
Section snippets
Materials and methods
This is a single center retrospective study in a public setting conducted at the Fertility Clinic at Hvidovre University Hospital in Copenhagen, Denmark. The sample of the study (n = 94) was retrieved from the clinical files and EmbryoScope database. 47 patients with normal ovarian response and 47 patients with low ovarian response according to the Bologna criteria after ovarian stimulation were finally included. Women with an AMH ≤ 7.8 pmol/L (measured with Beckman ELISA IOT corresponding to
Results
Patients in the low and normal ovarian response group did not differ regarding Body Mass Index (BMI), smoking habits, IVF/ICSI treatment, use of donor semen and the type of stimulation protocol (short GnRH antagonist or long GnRH agonist protocol) (Table 2). However, women with low ovarian response had less aspirated oocytes and a mean age of 36.6 years, while women with normal ovarian response had more aspirated oocytes and were statistically younger (32.9 years). On average, low responders
Discussion
We found no statistically significant differences regarding early morphokinetic parameters and cleavage patterns between patients with low and normal ovarian response when we adjusted for age. However, we showed a trend for the embryos from patients with low ovarian response to be more likely to cleave slightly slower at three cell (t3), though this has an indicative p-value (dif = 0.884 h; p-value < 0.046). Additionally, the risk for multinucleation at the 4-cell stage was significantly lower
Conflict of interest
None.
Acknowledgement
This work was made possible by an EU/Intereg Reprounion/ESHRE sponsored three months fellowship for EA.
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