The absence of a positive result after the transfer procedure can be a consequence of aneuploidy – the presence of chromosomal abnormalities in the genetic material of the embryo. According to statistics, the risks increase in proportion to a woman’s age. Accordingly, how many embryos are transferred during IVF also depends on the age of the future mother. The higher they are, the greater the risk percentage:
- Under the age of 35, one out of three healthy embryos is aneuploidy;
- After the age of 35 aneuploidies is more common in two embryos out of three;
- before age 40, five embryos out of six are abnormal;
- after age 44, only one embryo in ten has no chromosomal abnormalities.
During in vitro fertilization, the healthiest embryos with no abnormalities are selected for transplantation.
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To determine their viability and decide how many embryos to transfer during IVF, a pre-implantation genetic screening procedure is carried out. Its essence is as follows: after the fifth day of development trophectoderm is taken to detect chromosomal. The procedure is completely safe and allows identifying fully healthy embryos.
There are a number of unquestionable advantages of pre-implantation genetic screening, as follows:
- An embryo with the highest viability will be selected for implantation;
- The chances of getting pregnant from the first pregnancy increase many times over;
- It is possible to select the right number of embryos, i.e. the possibility of multiple pregnancy is excluded;
- Minimization of the risks of giving birth to a child with genetic abnormalities.
The genetic screening procedure also helps to identify abnormalities that may or may not show up later in the development of the embryo.
HOW MANY EMBRYOS ARE RECOMMENDED TO TRANSFER?
How many embryos can be implanted during IVF depends on many factors. For more information, it is recommended to read the experts’ answers to the questions that are especially often asked by clients who want to have a child by in vitro fertilization:
- What are the chances of successful in Vitro Fertilization and a favorable pregnancy outcome? If the genetic screening procedure has been performed, which resulted in the selection of the healthiest embryo, the success rate is higher than 60%. If we transfer two embryos without screening, the success rate ranges between 65%.
- How many embryos are implanted during IVF and what is the probability of multiple pregnancy? When two embryos are implanted, there is about a 30% chance of twins being born. If one embryo is selected for the procedure the chances of twins are also there, but it happens in 1 out of 100.
- What is the chance of a miscarriage? The risks of spontaneous abortion are present in every case of IVF. However, if an embryo is implanted after screening, the chance of miscarriage is no more than 11%, whereas if two embryos are implanted without this procedure, the chance is 20%.
- What is the risk of preterm birth? The probability of premature birth in a pregnancy through in-vitro fertilization is low, not more than 11% in a singleton gestation. In multiple gestation, the probability of premature birth is somewhat higher, at around 30%.
- What will the baby’s birth weight be? The figures given are usually standard. Most babies born after IVF procedure weigh about 3.5 kg. If there was a multiple pregnancy, the weight of the newborn is somewhat lower and usually does not exceed 2.7 kg.
- Is a baby at risk of developing cerebral palsy? The percentage of risk depends on whether or not there was a preimplantation genetic screening procedure. If this is done, the chance of being diagnosed with cerebral palsy is no more than 1/1000. If not, the risk increases slightly and is 7.4 per 1,000.
Without an individual approach to the situation, it is impossible to determine in advance which measure will be more effective – the implantation of one embryo after the screening procedure or two embryos without the involvement of such a procedure. It is advisable to consult a specialist to get answers that are as close to accurate as possible. In some cases, it is quite acceptable to implant two embryos, as the probability of a favorable outcome of pregnancy is high. Sometimes, however, a woman should postpone the issue of having a second baby for a little later.