How Are Twins Formed in IVF?

2024-05-13 17:09:46，visits： 402

In human reproduction, the occurrence of twins is always a fascinating phenomenon. Whether fraternal or identical, it sparks the interest of many. Particularly for those considering egg freezing and IVF, there is a heightened curiosity about how identical twins are formed.

The occurrence rate of identical twins is relatively low both in natural conception and IVF pregnancies. However, during the IVF process, the likelihood of identical twins is slightly higher, ranging from approximately 0.72% to 3.3%. There are several reasons for this phenomenon.

Firstly, it's important to understand that during the IVF embryo culture, the embryos may spend an extended period in the culture medium. This can cause the zona pellucida of the embryo to harden, leading to compression of the inner cell mass and subsequent splitting, resulting in the formation of two embryos. Additionally, a lack of growth factors or cytokines in the culture medium may also induce splitting of the inner cell mass, leading to the occurrence of identical twins. Other factors such as maternal age and the use of ovulation-inducing drugs may also play a role.

The process of a single embryo splitting into twins can occur in several stages. Within the first 72 hours after fertilization, if cell mass splitting occurs, it may result in the formation of twin placenta, fused placenta, twin chorions, twin amniotic sacs, or identical twins. Subsequently, between days 4 to 8 after fertilization and beyond day 8, cell mass splitting may lead to the formation of a single placenta, single chorion, single amniotic sac, or identical twins.

The majority of twins born through IVF are fraternal twins. Although many families may desire to have twins through IVF, experts do not recommend it due to the increased burden and risks associated with carrying twins simultaneously. Twins also share maternal nutrition, which may affect their relative allocation and increase the risk of premature birth. In comparison, the method of freezing embryos and transferring them at an appropriate time is considered safer and more reliable.

If you have any questions or need further information about IVF, we sincerely invite you to consult the expert team at IVF USA. Led by Dr. Nathan Zhang, our team has extensive experience and professional knowledge to provide you with the most suitable solutions. IVF USA currently offers egg freezing, IVF, and third-party reproductive services. Our services extend beyond the United States to include Japan, Thailand, Mexico, Taiwan, Hong Kong, and other regions. We collaborate closely with top IVF specialists worldwide. Whether you are facing the challenge of egg freezing or IVF, we are dedicated to providing you with support and assistance.