In Vitro Fertilization (IVF) is a medical procedure where an egg is fertilized by sperm outside the body in a laboratory setting. IVF offers a pathway to parenthood for those facing infertility. While some patients desire multiple births, such as twins, to achieve a larger family size in a single cycle, the medical community prioritizes the health of the mother and child. Policies actively discourage the intentional creation of multiple pregnancies due to complex medical and ethical considerations.
How IVF Multiples Occur and Transfer Policies
The primary mechanism leading to twins in IVF is the transfer of more than one embryo into the uterus, known as Double Embryo Transfer (DET). Transferring multiple embryos substantially raises the risk of a twin or higher-order multiple gestation. Conversely, Elective Single Embryo Transfer (eSET) involves placing only one embryo and is now the standard of care in many clinics for patients with a good prognosis.
Factors influencing a clinic’s decision on the number of embryos to transfer include the patient’s age, the quality of the embryos available, and the history of previous IVF cycles. For younger patients (under age 38) with high-quality embryos, eSET is usually recommended. This approach offers comparable cumulative pregnancy rates to DET over multiple cycles while significantly reducing the risk of multiples.
Health Risks of Carrying Multiples
The medical consensus discourages the intentional pursuit of multiples due to elevated health risks for both the mother and the babies. A twin pregnancy is classified as higher-risk compared to a singleton pregnancy. The mother faces increased chances of developing serious conditions such as gestational diabetes, preeclampsia, and gestational hypertension. Women carrying multiples are also more likely to require a Cesarean section, and they face a greater risk of complications like postpartum hemorrhage and anemia.
For the babies, the most prominent danger is premature birth, with approximately 60% of twins born before 37 weeks. Prematurity is directly linked to low birth weight, which can lead to various immediate and long-term health issues. These issues include respiratory distress syndrome, developmental delays, and extended stays in the Neonatal Intensive Care Unit (NICU). Twins also have a higher risk of conditions like cerebral palsy, making a singleton pregnancy the safest path to a healthy live birth.
Navigating Patient Requests for Twins
While a patient has the right to express a preference for twins, clinics are bound by medical guidelines and ethical obligations that prioritize a healthy singleton birth. The aim of assisted reproductive technology is to achieve the birth of one healthy baby, not to produce multiples. Therefore, a patient cannot simply choose to have twins; the decision rests with the medical team based on established safety protocols.
In some specific situations, such as advanced maternal age, multiple prior failed cycles, or when the available embryos are of lower quality, a clinic may agree to a Double Embryo Transfer (DET). This decision is made to increase the overall chance of achieving any pregnancy, not to guarantee a twin birth. Even with DET, the risk of a twin pregnancy is generally around 25% to 30%, depending on the patient’s specific factors and the quality of the embryos. The medical team balances the patient’s desire for success with the evidence of risk associated with multiple gestations.