More than 40 years ago, the main objective of assisted reproduction was to achieve the much-desired pregnancy, often without considering the risks of multiple pregnancies. To increase the chances of success, it was common to transfer two, three or even four embryos in the same cycle, which significantly increased the rate of multiple pregnancies. Over time, the vision changed: today, the real goal is to bring home a healthy newborn. Thanks to advances such as blastocyst culture, improved embryo selection, pre-implantation genetic testing (PGT) and the use of state-of-the-art incubators and better hormone stimulation protocols, it is no longer necessary to transfer multiple embryos to achieve good results. These advances have directly contributed to reducing the risks of multiple pregnancies. The Spanish Fertility Society (SEF) and other institutions recommend limiting the transfer to one or two embryos, especially promoting selective single embryo transfer (SET) in favourable cases. Studies show that two single embryo transfers can offer cumulative pregnancy rates similar to a double transfer, but with a much lower incidence of multiple pregnancies. For example, SET has a twin rate of 3.5%, compared to 38% for a double transfer.
What is your incidence of multiple pregnancies?
Multiple pregnancies affect 1-2% of natural pregnancies and increase substantially in pregnancies achieved through assisted reproduction. Being pregnant with more than one baby is the desire of many couples and can even be exciting. However, multiple pregnancies carry a higher risk of complications during gestation.
What is the incidence and what are the risks of multiple pregnancies?
The risk of multiple pregnancy is relatively low in natural pregnancies (1-2%), but increases considerably with assisted reproduction treatments.
Although some couples may find it desirable to have more than one baby, multiple pregnancies involve greater complications for both the mother and the foetuses. More than 50% of multiple pregnancies end in premature births. The more foetuses there are, the greater the risk of them being born before 37 weeks.
Premature babies often have low birth weight and immature organs. This can lead to difficulties in breathing, feeding or maintaining body temperature, and in many cases requires admission to a neonatal intensive care unit.
Other risks of multiple pregnancy include:
- Fetofetal transfusion syndrome (in monochorionic twin pregnancies)
- Increased likelihood of miscarriage or perinatal death
- Gestational hypertension, pre-eclampsia, and eclampsia
- Premature placental abruption
- Anaemia and gestational diabetes
- Excess amniotic fluid or premature loss of amniotic fluid
- Higher rate of caesarean delivery and postpartum complications
How can the risks of multiple pregnancies be prevented?
The best strategy for reducing the risks of multiple pregnancies in assisted reproduction is to limit the number of embryos transferred:
- In artificial insemination, ovarian stimulation is carefully controlled to prevent more than two or three follicles from developing.
- In in vitro fertilisation, selective embryo transfer of a single embryo (SET) is prioritised in women with a good prognosis.
Currently, fertility clinics in the UK, such as URE Centro Gutenberg, are highly committed to responsible embryo transfer to minimise the risks of multiple pregnancy. Thanks to advanced technologies such as embryo evaluation using time-lapse systems, the use of modern incubators and pre-implantation genetic testing (PGT), it is possible to select the embryos with the highest probability of implantation. This allows for single embryo transfer (SET) without compromising success rates. This strategy not only reduces the number of multiple pregnancies, but also improves obstetric and perinatal outcomes for both mother and baby.
Do you have questions about the risks of multiple pregnancies in fertility treatments?
At URE Centro Gutenberg, we offer you a personalised and safe approach, always prioritising your health and that of your future baby. Contact us today and discover how we work to minimise the risks of multiple pregnancies in each treatment.
