With rising incidence of infertility, IVF treatment becoming more commonly available and all the technological innovations with IVF procedure, there is an ever growing focus on minimizing the complications associated with IVF treatment. One of the common risks associated with IVF, which is also a major cause of distress among couples preparing to start IVF treatment, is the risk of multiple pregnancies. In fact, having twin pregnancy has become almost synonymous with undergoing the IVF treatment. And, my patients often ask me if they can conceive only twins with IVF? In reality about 1 in every 4-5 pregnancies resulting from ART are twins, a rate much greater than in the general population (1 in 80 pregnancies). The incidence of triplets and quadruplets is also higher among women undergoing ART. However, the majority of ART pregnancies (about 70%) are singletons.
The risk of multiple pregnancy in IVF cycle exists primarily because of the tendency to transfer more than one embryo inside the uterus to increase the chances of pregnancy. This is done as there are no tests or procedures which can assure us of pregnancy after IVF. The process of implantation of an embryo in the womb is a complicated one, and what transpires between the embryo and the womb that results in positive or negative pregnancy outcome is not fully understood. Therefore, in order to increase the chances of transferring an appropriate embryo, more embryos are transferred at a time. But, this puts the woman at risk of multiple pregnancy. But this does not mean that in the pregnancy rates increase proportionately to the number of embryos transferred. In fact, rather that increasing the overall pregnancy rates, transferring more than one embryos in one cycle actually increases the risk of multiple pregnancies, as more than one embryo may implant at a time.
Having twins may actually even sound tempting to many patients who have struggled to have a baby for long, but it is not as good as it sounds. Multiple pregnancy is associated with a higher rate of maternal, fetal and neonatal complications and is now considered as the single biggest risk of fertility treatment. Good practice in IVF aims to reduce risk of multiples in an IVF, whilst maintaining the overall chances of becoming pregnant. This is achieved by proper patient selection and counselling. I follow these three simple strategies to achieve the best clinical outcome from IVF procedure –
- Young women who have the best chance of conception also have the highest chance of conceiving multiples, so I prefer to do single embryo transfer in these patients. The remaining embryos can be frozen and preserved for later use
- An extended culture of embryos up to the day 5, called as blastocyst culture, allows us to select the best embryo for transfer, thereby improving the chance of pregnancy with single embryo transfer.
- For carefully selected set of women, who have had multiple IVF failures and who are not fit or willing for blastocyst culture, I transfer two high quality embryos, which gives the best possible chance of pregnancy with minimum possible risk of multiple pregnancies.
To sum it up, we need to counsel all our patients that only success parameter in any IVF cycle is a healthy baby born to a healthy mother, and reducing the number of embryos transferred in a cycle is a significant step in achieving this objective. Patients should be counselled about the risks associated with transferring many embryos and also explained the option to freeze the spare embryos, if any. If needed, subsequent cycles with both fresh and frozen embryos would give them even better cumulative pregnancy outcome than putting in several embryos in one cycle itself.
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