I.V.F-E.T : IN VITRO FERTILIZATION (IVF) PROCESS- THE EMBRYO TRANSFER & PREGNANCY TESTING

Patients undergoing In Vitro Fertilization (IVF) have numerous appointments, medications and procedures to navigate. Before a cycle begins, patients can feel intimidated about all the steps ahead of them.

At Shady Grove Fertility, want our patients to have all the information and support they need to make treatment as stress-free as possible. As part of that commitment, we have created a four-part series of articles in which we’ve described in detail how IVF is performed at our center.

This article, the third in the series, will help you learn what to expect in the last stages of an IVF cycle – from the embryo transfer to pregnancy testing and beyond. During this part of the cycle, your primary job is to rest and relax…let nature take its course. It sounds simple, but many patients will tell you that deciding how many embryos to transfer and waiting for the pregnancy test were actually the hardest parts of their cycles.

We hope this information helps you formulate questions for your doctor or nurse and think through the decisions you’ll need to make during this phase in the cycle. Above all, we want to reassure you that you are not alone. Thousands of patients successfully complete IVF cycles each year – and your medical team at Shady Grove Fertility is here to support you every step of the way.

About one in six IVF pregnancies result in a multiple birth. This is very high compared with natural conceptions of twins which occur in about 1 in 80 births.

Multiple births following fertility treatment present significant health risks to mothers and babies.

With IVF these risks are avoidable with the use of elective single embryo transfer (eSET) and frozen embryo transfer in appropriate patients.  

How does IVF work?

During IVF, eggs are removed from the ovaries and fertilised with sperm in a dish in the laboratory. The developing embryos can be left for either two to three days, or five to six days before being transferred to the woman’s womb.

1. After two to three days, the embryos are known as ‘cleavage stage’ embryos.
2. If the eggs are left to develop for five to six days after fertilisation, the developing embryos are known as ‘blastocysts’ and the procedure of transferring them to the womb is known as ‘blastocyst transfer’.

How does IVF affect the risk of multiple births?

Currently, after IVF and intra-cytoplasmic sperm injection (ICSI) around 16% of pregnancies are multiples, compared with only 1–2% after natural conception.

This can be directly related to more than one embryo being transferred during IVF and ICSI.

1. If two separate embryos implant in the womb, the mother will be pregnant with non-identical twins.
2. The chance of a single embryo dividing and resulting in identical twins is also higher after IVF, particularly after blastocyst transfer, however it is not yet known why this happens. So it is possible to end up with twins from the transfer of a single embryo, or triplets from two embryos.
3. Data from the UK (2013) shows that almost 15% of babies born as a result of IVF to women under 35 (using fresh eggs) are multiple births.
4. Although HFEA guidance states that the number of embryos that can be transferred is no more than two for women under 40 (or for those receiving donated eggs as donors are under 35) or no more than three for women over 40, the aim for all patients should be to have a single healthy birth.
5. Because of this all clinics must now have a strategy to minimise the risk of a multiple pregnancy, by using elective single embryo transfer where appropriate.

What are my options?

Your clinician will discuss your risk of having a multiple pregnancy and will recommend single embryo transfer if appropriate. Your clinic will discuss the best option for you.

1. If one embryo is transferred during IVF (single embryo transfer), the risks of multiple birth are greatly reduced.
2. Where additional good quality embryos are available, the clinic will advise freezing these for future use.
3. In some cases, the clinic may suggest transferring two embryos depending on your individual circumstances.
4. The latest research shows that, if you are young, healthy and have a good chance of conceiving with IVF, transferring only one embryo does not reduce the chance of pregnancy.

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