Embryo quality is not related with the baby’s health, but it gives us an idea of the ability of that embryo to implant and lead to a pregnancy. The so-called “embryo quality” in an IVF cycle is a morphological evaluation of the embryos at a specific time, over several days of observation under the microscope. This categorization has been related, in multiple studies, with the probability of pregnancy for each embryo. The morphological embryo quality does not give information about the genetic or metabolic quality of the embryo and, therefore, it’s not associated with the miscarriage risk, pregnancy development, or the baby´s health.
Relationship between embryo quality and baby’s health
There have been several attempts to correlate embryo quality, the health of the baby born and pregnancy development. Oron and col., in 2014, published a study of 1541 women under 41 years of age, who had a single embryo transfer in an IVF cycle. They analyzed pregnancy rate, miscarriage rate, life birth rate and perinatal outcomes according to embryo quality of the embryos transferred. Regarding perinatal outcomes, weight, preterm delivery, preeclampsia, placental abruption and neonatal complications were studied. They observed a higher pregnancy and delivery rate in those cases in which good quality embryos were transferred. But they did not find differences, according to the embryo quality of the embryos transferred, in the miscarriage rate or maternal or neonatal complications.
Embryo quality classification
Although there are many classifications, in Spain the classification of ASEBIR (Association for the study of Reproduction Biology) is the one used. In this classification, oocytes, embryos until day three of development and blastocysts (embryos until day seven of development) are evaluated. Embryos are assigned letters (A, B, C or D) according to their morphological embryo quality and are corelated with their probability of pregnancy. The best quality embryos are classified as “A” and are more likely to implant. Those of lower quality, are classified as “D” and have fewer possibilities.
Factors that influence embryo quality
The embryo quality depends on multiple factors, some are intrinsic factors, that is, the oocyte and sperm used to generate the embryo; and other factors, are extrinsic, such as embryonic culture conditions in the IVF laboratory.
As intrinsic factors, embryo quality depends on the gamete quality (oocyte and sperm), which, in turn, depends on the parents characteristics: age, endometriosis, polycystic ovarian syndrome, hyperprolactinemia, ovulatory factor, ovarian failure, male factor … The most important intrinsic factor is the age of the woman. Woman’s age cannot be changed and it´s responsible, to a greater extent, of embryo quality, pregnancy development, and baby´s health. Other intrinsic factors can be treated to try to improve embryo quality. For example, oocyte quality can improve after oral antidiabetics treatment in women diagnosed with polycystic ovaries; sperm quality sometimes improves with antioxidants and vitamins, with surgical treatment (in the case of varicocoele) or simply decreasing sexual abstinence. In case of overweight, cigarette or alcohol consumption, improving the diet and stopping unhealthy habits can improve both, oocyte and sperm quality.
As extrinsic factors, we can mention all those related with gamete in vitro processing and embryo culture. Laboratory conditions and culture media used are essential, since embryo quality depends, in a large extent, on them. And these factors can be modified. Careful monitoring of new investigations to improve embryo culture conditions, and the implementation of effective proven techniques in the IVF lab, is an essential part of the work of fertility clinics.
In URH García del Real, we take care of every detail to achieve the best quality embryos possible, according to the circumstances of each couple. If you have any questions about this topic, you can make an appointment for a free consultation, call +34 917401690 or we can also offer you a Skype appointment.
Dr. Isabel Pons Mallol – Head of the IVF and Andrology Laboratory