How Many Embryos To Transfer
When a woman undergoes in vitro fertilization (IVF), the fertility doctor has the ability to transfer multiple embryos during a single cycle. Although some couples are excited at the prospect of twins or triplets, other patients may fear the complications associated with a multiple pregnancy and life with 2 babies. Making an educated decision about how many embryos to transfer during IVF can help patients build or expand a family as safely as possible.
The IVF solution
Although any individual can pursue IVF, the reproductive technology is typically used by women who have been unable to conceive naturally after trying for at least a year. During IVF, the woman is given fertility medications to regulate the cycle and increase egg production. Mature eggs are then retrieved from the follicles and combined with a sperm sample in the lab to create embryos. Depending on the underlying fertility issues at play, some patients only end up with 1 viable embryo, while other individuals will have multiple embryos available to use or store.
Preparing for transfer
After the embryo has grown in the lab for a few days and undergone any necessary biopsies, such as preimplantation genetic testing (PGT), the specimen can be transferred back into the uterus in hopes of successful implantation. In most cases, elective single embryo transfer (eSET) is encouraged, meaning only a single healthy embryo is transferred. The use of eSET decreases the risks associated with a multiple pregnancy, like preterm delivery.
The desire for twins
Although eSET is considered the safest choice, a couple may desire twins for many reasons. Older age is often a driving factor. Women over 40 have limited time remaining to conceive and carry a pregnancy to term successfully. For these patients, a 2-for-1 approach sounds ideal. Other women may understandably think that transferring 2 or 3 embryos is more likely to result in a successful pregnancy, but research shows the opposite is, in fact, true. A recent study found that the live birth rate was 41.3% among women who underwent a fresh eSET transfer and just 32.6% in patients undergoing a double-embryo transfer. Lastly, some couples may just find twins cute, a fact that is hard to argue with.
Multiple health risks
Even though there are many reasons for desiring twins, the reality is that multiples come with an increased risk of complications. Higher rates of miscarriage, birth defects, preterm delivery, low birth weight, cesarean section, hypertension, and hemorrhage have been consistently proven to occur in twin pregnancies. Twin-to-twin transfusion syndrome (TTTS) is another serious complication worth considering. Due to these documented risks, most fertility providers will always start by recommending eSET. However, because each case is unique, there may be some situations where the benefits of twins outweigh the possible health risks.
The single solution
For women undergoing IVF, the best option is to select a single healthy embryo for transfer. With a dedicated fertility team and the proper medications, this approach is more likely to result in a successful pregnancy while reducing the known risks associated with multiples. Although twins may sound like a cute and easy option, the reality is that a single baby is much safer.
