Probability of twins with fiv and artificial insemination

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In vitro fertilization (IVF) and artificial insemination (AI), the main techniques of assisted reproduction, are associated with a higher probability of pregnancy in twins (non-identical twins) or of more infants. About 60% of twin pregnancies come from these techniques.

While it is true that these treatments may increase the likelihood of double pregnancy, many studies are currently aimed at reducing this type of pregnancy. The main reason is the high risk involved both in maternal health and in the development of babies.

Next you have an index with all the points that we are going to treat in this article.

Index

Probability of twins with IVF and artificial insemination

Twins or twins?

It is important to note that, in the case of double pregnancy after IVF, they are usually twin or twin twins and not identical twins or monozygotic twins. Here's the difference between the two:

  • Twins or bicyclic twins: they come from two eggs and two different spermatozoids, that is, from different embryos that have developed in the same pregnancy. They do not have to have the same sex or the same physical characteristics. Therefore, they would simply be two brothers who are the same age.
  • Identical twins: they come from the same embryo which, during the first rounds of cell division, has been fragmented into two parts giving rise to two identical embryos. Therefore, they contain the same genetic information, which means that they are necessarily of the same sex and very similar physically.

Regardless of whether they are identical twins or twins, pregnancies in which two fetuses develop simultaneously are called twins.

In Assisted Reproduction ORG you have the possibility to get the first free visit in a clinic to inform you of the treatment that suits you best.

Check out the discounts we have in the Discounts Section:

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Why is there a greater chance of twins' pregnancy?

It is estimated that, naturally, the probability of having twins is 1.1%. In contrast, that of having identical twins is 0.4%. In assisted reproduction, however, according to the statistical report of the Spanish Fertility Society (SEF) of 2014, the rates of twin births (both twins and twins) with their own eggs are 19.4% for each IVF transfer and 11.2% with artificial insemination.

Probability of twin delivery for assisted reproduction

The rates of pregnancy and twin birth increase considerably when using assisted reproduction techniques for two reasons:

  • Transfer of two or three embryos in in vitro fertilization.
  • Stimulation of ovulation to mature more than one ovule in artificial insemination.

In both cases there is the possibility of implanting more than one embryo, so a twin pregnancy could occur. The goal is to increase the probability of pregnancy, but this also increases the probability of multiple pregnancy (pregnancy of two or more babies).

To avoid this type of pregnancy, there is currently a tendency to transfer a single embryo and to control the medication in artificial insemination very well so that only 1 or 2 eggs mature.

In contrast, for a multiple pregnancy to occur naturally, the following factors influence:

  • Maternal age: the older the mother, the greater the probability of having twins, especially in women over 35 years of age.
  • Family inheritance: There is a greater probability of having a multiple pregnancy if there have been family history.
  • Race and geographical area: there is a higher incidence of twins in the black race, followed by Caucasian, Hispanic and Asian.
  • Maternal weight: a Body Mass Index (BMI) of 30 or higher causes a woman to have more than one ovule at each ovulation, so there is a greater chance of having twins.
  • Having previously had twins: having had a previous twin birth doubles the chances of re-conceiving two babies, since the woman has a tendency to release more than one ovule in each cycle.
  • Have had children before: women who have had one or more previous children are more likely to have a twin pregnancy than those who have their first pregnancy.
  • The diet: inadequate nutrition is accompanied by a lower rate of twin pregnancy, while women who eat properly and take supplements of folic acid have a higher rate.

Probability of twin pregnancy in IVF

In vitro fertilization (IVF) is an assisted reproductive technique in which women are given hormonal medication to stimulate ovarian production.

Thus, the development and maturation of more than one ovule is achieved and, therefore, a greater number of embryos will be obtained by recovering a greater quantity of eggs in the follicular puncture.

After the embryos are cultured, they will be transferred to those with greater implantation potential, that is, those of higher quality. It can be done on both day 3 and day 5, depending on the needs of the patient and the possibilities of the reproductive center.

The number of embryos to be transferred will be chosen by the patient, always taking into account the advice of the medical specialists and the laboratory. The Spanish law on techniques of assisted human reproduction (Law 14/2006) allows the transfer of up to three embryos.

This is a complicated decision. The goal is to achieve pregnancy, but without forgetting the risks related to double gestation. Therefore, more and more specialists recommend the transfer of a single embryo. Thanks to the improvement of the methods of embryo selection it is possible to have a very good probability of pregnancy with a single embryo, thus reducing the probability of multiple pregnancy.

According to data collected from 22 European countries by the European Society for Human Reproduction and Embryology (ESHRE), after an FIV or ICSI, 73.6% of pregnancies are single-born (single-pregnancy), while 24, 4% are twins.

On the other hand, according to the statistical report of the Spanish Fertility Society (SEF) of 2014, the rate of twin birth with own eggs for each transfer in Spain stands at 19.4% this year, while in 2000 was 28.7%.

Therefore, strategies followed by reproductive health professionals are lowering twin pregnancy rates.

Is there more chance of identical twins?

Although the majority of multiple pregnancies resulting from in vitro fertilization are from twins (dizygotic twins), there also appears to be a greater tendency for twin pregnancies (monozygotic twins).

It is estimated that there is an increase of approximately 1.5-2% of pregnancies of monozygotic twins. Therefore, even transferring a single embryo would have a small chance of pregnancy of twins.

Identical twin probabilities for in vitro fertilization

It is not known exactly why this increase occurs, although there are different hypotheses about the mechanisms that can justify it. The zona pellucida seems to have an important role, since for the embryo to implant it is imperative that it leaves this shell once it reaches the blastocyst stage.

In general, the embryo leaves without problems because it exerts a mechanical and enzymatic action on it, but, under certain circumstances, it may happen that the embryo is split in two when leaving the zona pellucida. It is believed that it can happen by:

  • The manipulation of the zona pellucida in ICSI (intracytoplasmic microinjection of spermatozoa), which can be used as an alternative to conventional IVF to fertilize the eggs.
  • Assisted hatching, which consists of making a hole in the zona pellucida to facilitate the exit of the embryo for later implantation.
  • The hardening of the zona pellucida caused by ovarian stimulation.
  • The development of the embryo in culture media under in vitro conditions.

Probability of pregnancy of twins by artificial insemination

In artificial insemination (IA), a previous step of ovarian stimulation is performed, only in a much milder way than in the case of IVF.

Low doses of medication are given to control the exact time of ovulation and so the semen is deposited at the optimum time, increasing the probability of pregnancy.

In order for a gestation of twins to be inseminated, it is necessary for two ovules to be expelled in ovulation, both of which are fertilized, that the two embryos generated develop into blastocyst and that they can implant.

In contrast, for a twin pregnancy, the embryo resulting from the fertilization of an egg must be divided into two. In an artificial insemination, the fact that the embryo is fragmented during its development does not seem to be increased, so the probability of identical twins can be considered the same as in a natural way.

According to the statistical report of the Spanish Fertility Society (SEF) of 2014, the percentage of twin pregnancies with artificial insemination is 10.6%.

User questions

How can I get pregnant with male twins by in vitro fertilization?

There is no way to increase the likelihood that they are identical twins or to ensure that two babies are going to get pregnant. However, it is possible to increase the likelihood of having twins when transferring two embryos. It is important to keep in mind that the risks increase in this type of pregnancy, since there is a greater probability of maternal and fetal complications.

In order to choose the sex of the embryos, a preimplantation genetic diagnosis (PGD) should be made, but in Spain sex selection is only permitted for therapeutic purposes.

Multiple pregnancy of twins is at greater risk because of in vitro fertilization or artificial insemination?

In principle there is no greater risk because pregnancy is achieved by assisted reproduction. The multiple pregnancy itself is considered high risk, whether it is achieved naturally or not. Pathologies such as gestational diabetes, hypertension or preeclampsia may appear in the mother in greater proportion.

In the baby, there may be prematurity and low birth weight. This implies that there are organs such as the lungs that are not mature and, therefore, the probability of survival is reduced.

Can I choose to have twins in my fertility treatment?

You can choose to transfer two embryos instead of one to increase the probability of pregnancy and thereby increase the likelihood of twin pregnancy. However, there is no way to ensure that both will be deployed.

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