Fertility Success Rates
So what’s my chance of having a baby? This is a difficult question to answer because so many factors are involved. First,your particular chance for success is impossible to predict. All we can do is estimate your odds based on other women with similar conditions. This means it might depend on factors such as your age, how well your ovaries work, whether your partner has sufficient quantities of sperm, the quality of his sperm, and whether or not you smoke.
Pregnancy is a very complex process that depends on the availability of “good” eggs, “good” sperm, and a uterus and hormone system that will produce a happy environment for implantation of an embryo. A “good prognosis” patient (someone who is relatively young with properly functioning hormones and a great uterus, for example) might have an almost zero chance of a pregnancy if she has a hidden factor such as eggs that don’t bind sperm, resulting in eggs that never become fertilized. For this reason, we can only estimate a pregnancy rate based on couples with infertility factors such as yours.
Pregnancy rates can be calculated based on the number of patients beginning treatment, the number of patients going for egg retrieval, or the number of patients having an embryo transfer. Each of these gives information to a clinician or embryologist, but most patients are interested in the probability of having a live birth once he or she starts treatment. This is often referred to as the live birth rate per initiated IVF cycle. The problem with this statistic is that the data are always about one year old, as one must wait for a baby to be born in order to count it as a live birth. Because of this, pregnancy rates sometimes include live births as well as those that are still in the uterus but have not yet been born. This is often referred to as theongoing pregnancy rate. This pregnancy rate is usually a little bit higher than the live birth rate, as some pregnancies will naturally miscarry, but it is usually the most current pregnancy rate and takes into account any recent technologies or changes that have been introduced into the clinic and laboratory.
One other important statistic is what is called the implantation rate. This is a measurement of the chances that a single embryo will implant in the uterus. By using this statistic, one can better understand the chances of having more than one embryo implant in the uterus, and this may aid a patient and the doctor determine whether to transfer one or two embryos. Implantation rates, as well as the other pregnancy rates mentioned above, are typically broken down by female age groups. The common age categories are: <35, 36-37, 38-39, and > or = 40.
To understand in-vitro fertilization (IVF) pregnancy success rates, we need to first understand the “natural” pregnancy rate – the pregnancy rate of women trying to conceive without any medical assistance. Humans are not very efficient at reproducing when compared to other species. For women in their early 30’s, a pregnancy rate of 20-25% per cycle (per month) has been estimated. This is why it often takes several months of trying in order to become pregnant. As women age, this rate drops to about 5% in women in their early 40’s. Realize this does not mean that each woman has a pregnancy rate of 5%; rather, as a group of 40 year olds they have a pregnancy rate of about 5%. This could mean that some women may have closer to a 0% chance while others may have higher chances. This age-related decline is usually attributed to a decline in the quality of eggs. Not only may eggs look poorer, but they also may have very high chances of having extra or fewer chromosomes, called aneuploidy. Several studies have shown that eggs and embryos from older women have more chromosomal abnormalities than those of younger women. Some women over 40 may have as high as 80-90% of their eggs chromosomally abnormal, meaning these eggs will not result in a live birth. Some of these chromosome abnormalities cause embryonic death, fetal death, or birth defects.
There is no way to repair these abnormal eggs. The best we can do to help is use a technique called Preimplantation GeneticScreening, or PGS, to select only normal embryos for transfer during IVF, but this assumes the patient has many embryos to choose from. One of the problems we often see with older patients is that they produce fewer eggs than younger patients and therefore may not have a sufficient number of embryos to undergo PGS.
A young age cannot guarantee a pregnancy, as there are several other hurdles to pregnancy that are not related to age. And, while advanced age is one of those factors for which we have no “cure”, we offer the technique of PGS to select only genetically normal embryos for IVF transfer.
One treatment option for infertility is insemination, often called Intrauterine Insemination, or IUI. Inseminations can increase one’s chances of conceiving by placing more sperm near the site of fertilization and by improving the timing of when the sperm and egg meet for fertilization. Inseminations can be done during a patient’s natural menstrual cycle, during which the timing of insemination is determined by using an ovulation predictor kit (a urine test) or the IUIs can be enhanced by increasing the number of “targets” for the sperm by giving the woman medications that allow her to produce more than one egg. These more aggressive treatments include the use of injectable hormones and often increase one’s risk of having twins or triplets (called a multiple gestation).
The factors that influence one’s chance of conceiving via IUI include the woman’s age and the quantity and quality of the man’s sperm. Also, the conduits through which the sperm and egg (and embryo) must travel (the fallopian tubes) must be normal. Because the typical pregnancy rate for insemination seldom exceeds the 20% rate of natural conception, it often takes more than one insemination cycle to have a good chance of getting pregnant. It is important to not spend too much time, though, doing inseminations if the woman is older (say > 37), as it may be advisable to move quickly to more aggressive treatments like IVF to increase the chance of pregnancy occurring much sooner and with fewer treatment cycles. Inseminations are less successful with such causes of infertility as severe male factor, advanced female age, diseased fallopian tubes, endometriosis, or decreased egg quality. Even with IVF, the chance for success with poor egg quality and/or advanced age may be quite low.
One of the major risks of insemination using injectable hormones is having more than one embryo implant in the uterus. This is a major concern, as the risks to both the mother and the child are increased. For example, the risks of cerebral palsy (CP) are increased 7-fold in twin compared to singleton pregnancies. To avoid these dangerous situations, some women who respond “too well” to the hormones (those who produce too many follicles) are not inseminated and are advised to use barrier protection until a new treatment cycle can be initiated with lower dosages of medications (where fewer follicles are produced) or are encouraged to consider progressing to IVF.
In Vitro Fertilization
Success of IVF also depends on many factors, the most important factor of which is probably the age of the woman. For this reason, most statistics are broken down by female age. IVFMD voluntarily reports their statistics to the Society for Assisted Reproductive Technologies (SART) which then forwards them to the Centers for Disease Control (CDC). These statistics, for reasons previously mentioned, are usually at least two years old. As an example, for 2013, the most recent statistics compiled by SART are for 2011. All infertility clinics are required to report to the CDC, whose statistics are often 3 years old. Using these data to compare success between different clinics may be misleading for several reasons. For example, a clinic with the highest pregnancy rates may not be the best clinic, as they may achieve their higher rate by transferring more embryos to the uterus and therefore increasing the risks to both mother and child. SART has guidelines for the number of embryos to transfer in order to decrease risks to mother and child, and IVFMD adheres to those guidelines to prevent transferring too many. For this reason, it is always important to examine the mean number of embryos transferred. As another example for the reason it may be misleading to compare IVF clinics, one center may not allow certain groups of women to undergo IVF for fear they will lower their pregnancy rates.
Most embryo transfers at IVFMD are with day-5 or day-6 embryos, called blastocysts. By using blastocysts, fewer embryos can be transferred without decreasing one’s chance for conceiving. This occurs because embryos must overcome a developmental hurdle at some time between day 3 and day 5 of embryo development, a time during which 30-50% of embryos will stop growing. Therefore, 50-70% of day-3 embryos will not make it to day 5. While day-3 embryos have an implantation rate of about 15%, the implantation rate for blastocysts is closer to 50%. By waiting to transfer on day 5, we can select those embryos that have the best chance for implanting and thus fewer embryos need to be transferred. Blastocysts are also easier to freeze, and they survive thawing more readily than day-3 embryos, partly because they have more cells.
Another important piece of data to examine when considering IVF success is the percent of frozen embryo cycles (calledFET) that result in a pregnancy. Frozen embryos give patients extra chances to conceive from extra embryos produced during the fresh IVF cycles. By choosing a center with a good FET program, you will not only have a better overall chance of pregnancy, but your treatment can be safer for several reasons: frozen embryos can be depended upon for pregnancies; embryos can be frozen if there are problems with your uterus after stimulation; and your embryos can be frozen and used at another time if you develop a potentially dangerous side effect (called severe ovarian hyperstimulation syndrome, or OHSS) during your fresh IVF cycle.
IVFMD uses a fairly new (but well-proven) technique to freeze embryos called vitrification. This technique freezes the embryos at a much quicker rate and results in less damage to the embryos than the traditional slow-cooling method. Combined with laser collapse of the blastocyst cavity prior to freezing, high survival rates have been achieved resulting in high pregnancy rates.
Donor Eggs and IVF
One of the most daunting factors affecting pregnancy rates is maternal aging. As a woman’s age increases, so too does the number of abnormal eggs. In addition, older women produce fewer eggs. There are some diagnostic tests that can be used to predict potential problems with age and eggs. The measurement of two blood hormones, Anti-Müllerian Hormone (AMH) and Follicle Stimulating Hormone (FSH), can be used to help estimate “ovarian aging.” So what can a woman do if she is either older or has premature ovarian aging? One of the best options is the use of donor eggs.