The number to be transferred depends on the number available, the age of the woman and other health and diagnostic factors. In countries such as Canada, the UK, Australia and New Zealand, a maximum of two embryos are transferred except in unusual circumstances. In the UK and according to HFEA regulations, a woman over 40 may have up to three embryos transferred, whereas in the US, there is no legal limit on the number of embryos which may be transferred, although medical associations have provided practice guidelines. Most clinics and country regulatory bodies seek to minimise the risk of multiple pregnancy, as it is not uncommon for multiple embryos to implant if multiple embryos are transferred. Embryos are transferred to the patient's uterus through a thin, plastic catheter, which goes through her vagina and cervix. Several embryos may be passed into the uterus to improve chances of implantation and pregnancy.
A recent large population-based study collected data from almost 5000 European patients. According to preliminary results presented at the 2019 European Society of Human Reproduction and Embryology, there is no benefit from ICSI in non-male factor cases. Importantly, the study reported no benefit of using ICSI regardless of how many eggs are retrieved after ovarian stimulation. Therefore, having a low oocyte yield should not be a reason for choosing ICSI over IVF.
Laboratories have developed grading methods to judge ovocyte and embryo quality. In order to optimise pregnancy rates, there is significant evidence that a morphological scoring system is the best strategy for the selection of embryos.[72] Since 2009 where the first time-lapse microscopy system for IVF was approved for clinical use,[73] morphokinetic scoring systems has shown to improve to pregnancy rates further.[74] However, when all different types of time-lapse embryo imaging devices, with or without morphokinetic scoring systems, are compared against conventional embryo assessment for IVF, there is insufficient evidence of a difference in live-birth, pregnancy, stillbirth or miscarriage to choose between them.[75] Active efforts to develop a more accurate embryo selection analysis based on Artificial Intelligence and Deep Learning are underway. Embryo Ranking Intelligent Classification Assistant (ERICA),[76] is a clear example. This Deep Learning software substitutes manual classifications with a ranking system based on an individual embryo's predicted genetic status in a non-invasive fashion.[77] Studies on this area are still pending and current feasibility studies support its potential.[78]
The main cause of male infertility is low semen quality. In men who have the necessary reproductive organs to procreate, infertility can be caused by low sperm count due to endocrine problems, drugs, radiation, or infection. There may be testicular malformations, hormone imbalance, or blockage of the man's duct system. Although many of these can be treated through surgery or hormonal substitutions, some may be indefinite.[57] Infertility associated with viable, but immotile sperm may be caused by primary ciliary dyskinesia. The sperm must provide the zygote with DNA, centrioles, and activation factor for the embryo to develop. A defect in any of these sperm structures may result in infertility that will not be detected by semen analysis.[58] Antisperm antibodies cause immune infertility.[23][24] Cystic fibrosis can lead to infertility in men.
This chart is US national average data on success rates per IVF cycle by female age for 2014. The dark blue line (triangles) shows pregnancy rates per cycle by age. The orange line (circles) shows live birth rates per cycle by age. The rate of singleton live births per cycle is shown by the light blue line. The difference between "pregnancy" rate and "live birth" rate is due to miscarriages.
A woman's age is a major factor in the success of IVF for any couple. For instance, a woman who is under age 35 and undergoes IVF has a 39.6% chance of having a baby, while a woman over age 40 has an 11.5% chance. However, the CDC recently found that the success rate is increasing in every age group as the techniques are refined and doctors become more experienced.
Fertility expert Zita West has noticed this increase at her London clinic. "The main reason," she explains, "is age. Women are having babies later." Exhaustion also plays a part. "The sleeplessness of life with a small child can't be underestimated," she says. "You might still be breastfeeding, you might be sharing a bed with a toddler, you might be holding down a job at the same time. Basically, there's not a lot of sex happening."
In the natural process of conception without treatment, a woman’s ovaries produce a mature egg each month, which leaves the ovary and travels along the fallopian tube towards the uterus. Sperm that has been deposited in the vagina through intercourse travels through the cervix through the uterus and up the fallopian tube toward the egg. Millions of sperm are lost in the cervix and do not travel to the fallopian tube. When the two meet, they join to form the early stage of an embryo which then travels down the fallopian tube into the uterus. If all goes well, it will implant in the lining of the womb and pregnancy begins.

Progesterone elevation on the day of induction of final maturation is associated with lower pregnancy rates in IVF cycles in women undergoing ovarian stimulation using GnRH analogues and gonadotrophins.[23] At this time, compared to a progesterone level below 0.8 ng/ml, a level between 0.8 and 1.1 ng/ml confers an odds ratio of pregnancy of approximately 0.8, and a level between 1.2 and 3.0 ng/ml confers an odds ratio of pregnancy of between 0.6 and 0.7.[23] On the other hand, progesterone elevation does not seem to confer a decreased chance of pregnancy in frozen–thawed cycles and cycles with egg donation.[23]
ART techniques generally start with stimulating the ovaries to increase egg production. After stimulation, the physician surgically extracts one or more eggs from the ovary, and unites them with sperm in a laboratory setting, with the intent of producing one or more embryos. Fertilization takes place outside the body, and the fertilized egg is reinserted into the woman's reproductive tract, in a procedure called embryo transfer.
On or after the day of your retrieval, and before the embryo transfer, you'll start giving yourself progesterone supplements. Usually, the progesterone during IVF treatment is given as an intramuscular self-injection as progesterone in oil. (More shots!) Sometimes, though, progesterone supplementation can be taken as a pill, vaginal gel, or vaginal suppository.

Success rates for IVF depend on a number of factors, including the reason for infertility, where you're having the procedure done, and your age. The CDC compiles national statistics for all assisted reproductive technology (ART) procedures performed in the U.S., including IVF, GIFT, and ZIFT, although IVF is by far the most common; it accounts for 99% of the procedures. The most recent report from 2016 found:
Our team here at the Center for Human Reproduction has recently developed an infographic explaining one of the most common causes of female infertility: unexplained infertility. This diagnosis is given to 30% of infertility cases and yet, we believe it really is a non-diagnosis. In our clinical experience, with proper testing, up to 90% of unexplained infertility diagnoses can be attributed to treatable causes.
Women are born with about 1 million to 2 million eggs but release only 300 to 400 through ovulation during their lifetimes. Usually, you release just one each month. The egg travels along one of the two fallopian tubes that connect your ovaries to your uterus. If the timing is right, sperm may fertilize it on its way to the uterus. If fertilization doesn't happen within 24 hours of the egg leaving the ovary, the egg dissolves. Sperm can live for about 3 to 5 days, so knowing when you are ovulating can help you and your partner plan sex for when you're most likely to conceive.

Cancer. Although some early studies suggested there may be a link between certain medications used to stimulate egg growth and the development of a specific type of ovarian tumor, more-recent studies do not support these findings. There does not appear to be a significantly increased risk of breast, endometrial, cervical or ovarian cancer after IVF.

Spend quality time with your child. In the midst of your infertility problems, you may feel especially upset about shifting your focus from the child you already have to the child you’re longing to have in the future. You may even feel guilty about your inability to give your little one a sibling or about the sadness you are sure is spilling over into her life. The best thing you can do for your child in this situation is to keep life as normal as possible, and ideally, find some quality time to be together. Whether it’s a chat about her day before you tuck her into bed or an afternoon romp in the park, those rituals will go a long way toward keeping your tot’s world stable and happy — even if you sometimes feel your world is spinning out of control. (You might find that focusing on your child lets you live in the moment — at least for a little while — which can help you cope with secondary infertility.) If you’re in a particularly bad place and fear that you may have a hard time handling your true emotions in front of your child (say, your pregnancy test just came up negative for the zillionth time in a row), see if you can arrange to send her to a friend’s house, or enlist your partner or mother-in-law to take over for a bit. Allowing yourself the time to compose yourself can make it much easier to face your little pride and joy with a smile.


Low weight: Obesity is not the only way in which weight can impact fertility. Men who are underweight tend to have lower sperm concentrations than those who are at a normal BMI. For women, being underweight and having extremely low amounts of body fat are associated with ovarian dysfunction and infertility and they have a higher risk for preterm birth. Eating disorders such as anorexia nervosa are also associated with extremely low BMI. Although relatively uncommon, eating disorders can negatively affect menstruation, fertility, and maternal and fetal well-being.

Spend quality time with your child. In the midst of your infertility problems, you may feel especially upset about shifting your focus from the child you already have to the child you’re longing to have in the future. You may even feel guilty about your inability to give your little one a sibling or about the sadness you are sure is spilling over into her life. The best thing you can do for your child in this situation is to keep life as normal as possible, and ideally, find some quality time to be together. Whether it’s a chat about her day before you tuck her into bed or an afternoon romp in the park, those rituals will go a long way toward keeping your tot’s world stable and happy — even if you sometimes feel your world is spinning out of control. (You might find that focusing on your child lets you live in the moment — at least for a little while — which can help you cope with secondary infertility.) If you’re in a particularly bad place and fear that you may have a hard time handling your true emotions in front of your child (say, your pregnancy test just came up negative for the zillionth time in a row), see if you can arrange to send her to a friend’s house, or enlist your partner or mother-in-law to take over for a bit. Allowing yourself the time to compose yourself can make it much easier to face your little pride and joy with a smile.

Cancer. Although some early studies suggested there may be a link between certain medications used to stimulate egg growth and the development of a specific type of ovarian tumor, more-recent studies do not support these findings. There does not appear to be a significantly increased risk of breast, endometrial, cervical or ovarian cancer after IVF.
While PGD was originally designed to screen for embryos carrying hereditary genetic diseases, the method has been applied to select features that are unrelated to diseases, thus raising ethical questions. Examples of such cases include the selection of embryos based on histocompatibility (HLA) for the donation of tissues to a sick family member, the diagnosis of genetic susceptibility to disease, and sex selection.[97]
A 2013 review and meta analysis of randomised controlled trials of acupuncture as an adjuvant therapy in IVF found no overall benefit, and concluded that an apparent benefit detected in a subset of published trials where the control group (those not using acupuncture) experienced a lower than average rate of pregnancy requires further study, due to the possibility of publication bias and other factors.[34]
Sometimes problems getting pregnant for a second or subsequent time are related to a complication that occurred in a prior pregnancy or prior to delivery (damage to the uterus, for instance). But most often, secondary infertility is caused by the same factors that would cause primary infertility — issues like advanced age, obesity, ovulation problems and so on.
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