All of our patients come to us with the desire for a healthy child. Yet at times, the medical challenges can be substantial. And the technology we apply, though quite remarkable, bypasses hard-won evolutionary adaptations. How does this impact our patients’ desired outcome? Over the past 25 years, there has been a lot of research in to IVF outcomes, but unless you are reading this literature closely, the results can be confusing. I would like to take a few minutes to clarify what we know at this time.
First, it is good to understand “what is normal?” Is it just survival and anatomic development? What about behavior? Intelligence? Achievement? Reproductive potential? I think all of us would agree that all of these factors would contribute to what we would define as a normal individual. It is also important to understand where the data comes from. There are a variety of sources and approaches, each with their strengths, limitations and biases. Was the information collected for this purpose or for another? How was it collected? Does the size of the study matter? (yes) So with all of this in mind, let’s take a look at what we know. We will be focusing on single pregnancies since the data suggests IVF multiples carry the same risks as spontaneously conceived multiples.
Miscarriages. At this point, most of us agree that there appears to be no difference in the clinical miscarriage rate in IVF pregnancies compared to natural conceptions. This rate is age dependent, but is also dependent on the number of eggs a woman has regardless of age. An excellent 2001 study from France observed a 2.8 fold increase in Down’s Syndrome, regardless of age, when the FSH > 11.5. The biochemical pregnancy (very early miscarriage) rate runs 8-11% but increases beyond this in mid 40’s.
Birth Defects. Numerous studies have now demonstrated that IVF single pregnancies have a slightly increased risk of birth defects compared to the general population, however, to understand the impact of the technology, you need a different control group: infertile women who conceive naturally. In the studies making the correct comparison, there is uniformly no difference. This suggests that IVF does not increase birth defects to any substantial degree.
Still Birth or Death Within the First Week of Life. Three studies published over the last decade suggest an increased risk of 1.6-2.1 when compared to the general population.
Pre-Term Delivery. A number of studies have demonstrated an increased risk of pre-term delivery in IVF babies vs. the general population. But again, getting pregnant later in life has been demonstrated to have a similar risk so the technology may not be the primary cause.
Other Pregnancy Complications. Several studies suggest a 1.5-2 fold increase in cesarean sections. A few report about a 1.5 fold increased risk of pre-ecclampsia , gestational diabetes and SGA. All of these are compared to the general population.
Childhood Cancers. Last year a large (n=106,013) study from England reported no overall increased risk of cancers. Insufficient time has passed to make a judgment regarding adulthood cancers.
Long-Term Development. Compared to the general population, there appears to be no increased issues in general health, growth, chronic illnesses, developmental stage, behavior, emotional functioning or autism risk in IVF children. Pubertal development appears normal. In adolescents and young adults, behavioral, social and emotional function appears appropriate.
What Can We Conclude? It is clear that our infertile patient population is a higher risk population compared to the general population. Fortunately, these risks appear to be quite small. The role of IVF in causing the problems has clearly not been demonstrated, but we also know it has not been excluded at this time. What we do know is that the vast majority of the over 3 million children born from IVF are normal, but we must remain vigilant to make sure that our evolving approaches and technologies continue to enhance outcomes.