19 Jan 2022
In vitro fertilisation (IVF) is a form of assisted reproduction that has been closely linked to the conception of twins. It is not uncommon for patients that undergo this procedure to request their doctors to arrange for such multiple births. But is this something that can be orchestrated and is it safe?
The answer is not quite clear cut. When undergoing IVF treatment, a woman’s ovaries are stimulated to produce many eggs. When matured, these eggs are retrieved and mixed with healthy sperm from the male partner or donor. This allows for fertilization to occur and embryos to develop.
After genetic testing to identify healthy embryos, a select few are transferred into the woman’s uterus in hopes of successful implantation that will confirm pregnancy. The trend has been to transfer more than one embryo into the woman’s uterus, especially when there is a higher risk of the treatment failing due to such factors as the woman’s age or a history of failed IVF treatments. The idea that prevailed was that by implanting more than one embryo, a woman was likely to at least have one successful implantation.
However, this policy resulted in a higher than usual rate of multiple pregnancies for women that conceived through IVF. The birth of twins rose by about 72% between 1980 and 2018. Non-identical twins are the most common type of multiple pregnancies that occurs with infertility treatments.
Some countries are now limiting the number of embryos that can be transferred in a single cycle of IVF treatment. This change in regulations has seen a drastic reduction in the number of multiple births from assisted reproduction procedures.
A few countries like the UK will allow no more than two embryos to be transferred for women under the age of 40 and no more than three embryos for women over this limit. In the US, the American Society for Reproductive Medicine (ASRM) has issued guidelines for single embryo transfers for women with a good prognosis under the age of 35 years. Other countries have no strict regulation in place, with IVF clinics setting their own standards. There is also no assurance that a doctor will adhere to the upper limit set by regulators. Some prefer to stick to single embryo transfers. This is to avoid the risks associated with a woman undertaking a multiple pregnancy.
So while IVF treatment may increase chances of having multiple births, it technically depends on how many embryos you are allowed to have transferred, whether the specialist is willing to abide by the legal limit, and if successful implantation of all the embryos occurs. So while IVF has resulted in an increased rate of twin births, there is no assurance that even with multiple embryos transfer that you will conceive and birth twins.
Whether you have a single or more embryo transfer, your chances of successful implantation and carrying the child to term may hinge on other factors as:
Twins are an alluring prospect for anyone undergoing fertility treatment as they represent the promise of double the luck. IVF treatments can be stressful. They are expensive and can be taxing both physically and emotionally. Being able to conceive and birth two babies at once means that hopeful parents can get their dream family at a faster speed than having to endure the process twice over.
Once the children are born, you only have to deal with the disruption and upbringing once. It is also appealing because you know your child will likely always have a close sibling. They will never be lonely and can support each other through life. Since many parents that pursue IVF do so because they are older now and are faced with declining fertility, it is also a big help to be able to birth multiples on the first go so they do not have to wait longer to raise them if they want more than one child.
So while there may be some merit to wanting to conceive multiple babies, there are associated risks that have pushed the medical fraternity to set limits on embryo transfers and discourage this desire.
Carrying more than one foetus comes with a higher risk of certain complications for both the mother and the children. Multiple pregnancies mean that the mother is at increased risk of suffering
Preeclampsia – this is whereby the mother’s blood pressure becomes elevated, resulting in her suffering life-threatening complications such as seizures and stroke.
Gestational diabetes – the mother may become diabetic during pregnancy which may lead to an increased risk of the children developing respiratory complications and other problems.
The babies are also more likely to be born underweight and prematurely. This may be linked to placental problems whereby inadequate oxygen and nutrients reach the foetuses. This is most likely to occur in the third trimester. Preterm deliveries can also increase the likelihood of the children developing some lifelong health complications or early death. There is often underdevelopment of organs such as lungs that contribute to this. Disability is also at a high rate, occurring in as much as 25% of births where the child is born while less than 2 pounds.
While having twins would be a wonderful outcome for hopeful parents undergoing IVF, it is not a goal fertility specialists pursue. They aim to see their patients conceive and deliver a healthy baby. Due to the many risks that come with multiple pregnancies and births, they would prefer to avoid placing their patients in such danger. Every effort is made before embryo transfer to ensure that the highest quality embryos are selected which will increase chances of implantation occurring.
While there is no harm in consulting with your doctor on the topic, keep in mind that it is better to safely deliver one baby than undergo a riskier pregnancy that may or may not lead to further complications for your future child.