From the Guidelines
If you are a twin and have 2 embryos implanted during fertility treatment, you do have an increased chance of having twins, with a likelihood of approximately 30-40%, compared to the natural twin rate of about 3%. Being a twin yourself suggests a possible genetic predisposition to multiple births, particularly if you are a fraternal twin. When two embryos are transferred during procedures like IVF, the chance of both successfully implanting and developing is significant, as noted in the ESHRE guideline on the number of embryos to transfer during IVF/ICSI 1. However, not all implanted embryos will successfully develop, and sometimes one embryo can split to form identical twins. Your personal medical history, age, and the quality of the embryos also influence the outcome. It's essential to discuss the specific risks and possibilities with your fertility specialist, as twin pregnancies carry higher risks, including premature birth, low birth weight, and pregnancy complications, as highlighted in the ACR Appropriateness Criteria for multiple gestations 1.
Some key factors to consider when deciding on the number of embryos to transfer include medical, economic, social, and psychological consequences of transferring more than one embryo, as well as patient wishes regarding family building and clinical recommendations for the specific patient case 1. The ESHRE guideline strongly recommends that healthcare professionals discuss these issues with patients and involve both members of the patient couple in the decision-making process.
It's also important to note that elective single embryo transfer (eSET) is considered the preferable approach towards safe and effective ART, as it reduces the risk of multiple pregnancies and associated complications 1. However, the decision to transfer one or more embryos should be made on a case-by-case basis, taking into account the individual patient's circumstances and the quality of the embryos.
In terms of the risks associated with twin pregnancies, it's crucial to be aware of the potential complications, such as premature birth, low birth weight, and pregnancy complications, as well as the increased risk of congenital anomalies and placenta previa 1. Regular ultrasound monitoring and antenatal surveillance can help identify potential complications early on and improve outcomes for both the mother and the babies.
Ultimately, the decision to transfer two embryos during fertility treatment should be made after careful consideration of the potential risks and benefits, and in consultation with a fertility specialist who can provide personalized guidance and support throughout the process.
From the Research
Risk of Having Twins with 2 Embryos Implanted
- If you are a twin and have 2 embryos implanted, the risk of having twins is higher compared to having only one embryo implanted 2.
- A study found that transferring two good-quality embryos was associated with significantly higher rates of twin pregnancy compared to transferring one good-quality or no good-quality embryo (26% vs 12.8% vs 9.3%) 2.
- However, the study also found that female age over 35 and poor-type endometrium were associated with reduced rates of twin pregnancy 2.
Factors Affecting Twin Pregnancy
- The decision to transfer one or two embryos during in vitro fertilization (IVF) remains inconclusive, as it depends on various factors such as the woman's age, embryo quality, and medical history 2, 3.
- A study found that IVF accounted for 21.4% of twin births and all triplet births in a given population, highlighting the increased risk of multiple births with IVF 3.
- Another study found that singletons conceived through IVF had increased risks of preterm birth and low birth weight compared to spontaneously conceived singletons, even after controlling for maternal age 4.
Perinatal Outcomes
- A study found that preimplantation genetic diagnosis (PGD) was not associated with an increased risk of preterm birth or low birth weight compared to autologous IVF cycles 5.
- Another study found that frozen embryo transfer (FET) was associated with lower risks of placenta previa, placental abruption, low birth weight, and perinatal mortality compared to fresh embryo transfer, but higher risks of pregnancy-induced hypertension and large for gestational age 6.