1、 Reproductive technology
Reproductive technology is one of the important factors that affect the ratio of male to female in the second generation of IVF. At present, the widely used IVF technology mainly includes in vitro fertilization (IVF) and preimplantation genetic diagnosis (PGD). In the process of in vitro fertilization, doctors collect female eggs and male sperm, and place them in culture dishes for fertilization. Then, after culture and screening, select the best quality embryos to implant into the female uterus. In PGD technology, embryos carrying certain sex genes are screened by genetic testing of embryos, so as to achieve the purpose of sex selection.
The development and application of these reproductive technologies provide a feasible way to choose the sex of IVF. However, according to the restrictions of relevant laws and regulations as well as ethical and moral principles, some countries or regions have strict restrictions on the sex selection of IVF. Therefore, the impact of reproductive technology on the male female ratio of second-generation IVF varies from region to region.
In addition, reproductive technology itself has certain technical limitations. For example, in PGD technology, there may be some errors in genetic screening of embryos. Therefore, the impact of reproductive technology on the male female ratio of second-generation IVF infants needs to be considered in combination with other factors.
2、 Genetic factor
The sex ratio of the second generation IVF is also affected by genetic factors. The sex is determined by the sperm carried by the father. The sperm carrying X chromosome is female sperm, and the sperm carrying Y chromosome is male sperm. Therefore, the ratio of X and Y chromosomes in the father's sperm will directly affect the ratio of male to female in IVF.
However, the proportion of X and Y chromosomes in father's sperm is not completely random, but is affected by a series of genetic mechanisms, including the sequencing mechanism of genetic material in the process of spermatogenesis, and the genes related to sex determination in genetic material. The complexity of these genetic mechanisms makes the male female ratio of IVF also subject to genetic factors.
In addition, some studies have shown that the mother's childbearing age may also be related to the ratio of men to women in IVF. Mothers of different ages may affect the chromosome behavior during egg development, thus indirectly affecting the sex of IVF.
3、 Disease treatment
The treatment of certain diseases may also affect the ratio of men to women in IVF. For example, some therapies or drugs have an impact on the implantation and development of embryos, which may lead to different survival rates of male and female embryos. These different survival rates may have an impact on the final sex ratio of IVF.
In addition, some studies also found that certain diseases, such as polycystic ovary syndrome, were related to the ratio of men to women in IVF. These diseases may change the endocrine system of female patients, thus affecting the combination and fertilization process of sperm and egg, and ultimately affecting the sex ratio of IVF.
4、 Cultural and social factors
The male female ratio of IVF is also influenced by cultural and social factors. In some societies and cultures, boys are endowed with higher values and status. Therefore, some families may prefer to choose boys as the sex of IVF. The existence of this preference may lead to the imbalance of the ratio of men and women in IVF.
At the same time, social expectations for the ratio of children may also affect the ratio of men and women in IVF. For example, in some areas, people generally hope to have a family with both sexes, which may make the sex selection of IVF more balanced. Therefore, the influence of cultural and social factors on the male female ratio of the second generation IVF cannot be ignored.
Summary
To sum up, the male female ratio of second-generation IVF infants is affected by many factors. The development of reproductive technology provides a way to choose the sex of IVF, but it is limited by laws, regulations and ethics; The proportion of X and Y chromosomes carried by sperm is different due to genetic factors; Disease treatment may lead to different survival rates of male and female embryos; Cultural and social factors affect the family's gender preference and expectations for the proportion of children. Therefore, the formation of the male female ratio of the second-generation IVF is a comprehensive process.
