"If you want to have a baby, just make a test tube baby?" In fertility counseling clinics, such questions are not uncommon. With the popularization of assisted reproductive technology, many families regard IVF as a "customized fertility tool" and believe that they can independently choose the gender of the fetus or deliberately pursue twin pregnancies.
,.In the case of natural conception, the probability of having twins is only about 1%, but through IVF technology, this probability can be increased to about 20%. Doctors sometimes transfer two embryos. If two embryos are successfully implanted and developed at the same time, twins are formed. If the two embryos happen to be of different sexes, a dragon and phoenix fetus will be formed.
,“”.Twin pregnancy is medically regarded as a high-risk pregnancy. It may cause complications such as gestational hypertension, diabetes, and postpartum hemorrhage to the mother, and may increase the risk of premature birth and low birth weight to the fetus. Therefore, the global consensus in the reproductive medicine community is to give priority to recommending single embryo transfers to ensure the safety of mother and infant.
1. Technical possibility and randomness
The core mechanism for IVF to increase the probability of twins lies in the number of embryos transferred.
.The number of embryos transferred must strictly follow the principle of individualized evaluation: single embryo transfer is generally recommended in clinical practice for patients under 35 years old and with good ovarian function; patients aged 35-40 can be relaxed to 2 embryos based on the quality of embryos; even if the age is over 40 years old, the number of transplants usually does not exceed 3. If a woman's physical conditions are appropriate, however, even if two embryos are transplanted, the outcome is still multiple: it may be twins (about 20% probability), it may be a single fetus (only one embryo is implanted), or even all implants may fail.
“”,.When the two transplanted embryos happen to be a male and a female, a dragon and a female can be formed. However, the gender of the embryo is randomly determined at the moment of fertilization, and fertility doctors cannot judge the gender of the embryo with the naked eye before transplantation.
It is worth mentioning that if only one embryo is transplanted, even if this embryo naturally divides into two fetuses in the uterus (with a probability of about 3%-5%), it will still result in identical twins. In other words, both fetuses will have the same gender, and it is impossible for them to be fraternal twins.
2. Strict legal and ethical restrictions
my country's "Administrative Measures for Human Assisted Reproductive Technology" clearly stipulates that fetal gender identification and selection for non-medical needs are strictly prohibited.
<>,.This means that unless one or both couples have a genetic disease with sexual chromosome connections (such as hemophilia, Duchenne muscular dystrophy, etc.), embryonic genetic diagnosis through the third generation in vitro fertilization technology (PGD) is required to avoid inherited diseases in offspring, otherwise any form of XY selection is illegal.
(PGD/PGS),,,.These are illegal operations and patients should remain vigilant.
3. Treat technology rationally and respect the laws of life
The core mission of IVF technology is to help infertile couples give birth to a healthy new life.
.Pursuing a specific gender or fetal number is not only not allowed by law and recommended by medicine, but also deviates from the original intention of technological development.
,,,,,.On the road to life inheritance, health and safety are far more important than gender and quantity.