The majority of miscarriages are related to genetic abnormalities of the embryo. The genetic materials are contained in the structures called chromosomes. Some bits may be missing or there may be too many copies of another one. These may be incompatible with life, therefore, miscarriages.
The vast majority of miscarriages are caused by abnormalities in the number of chromosomes contained in the embryo. Human beings normally have 23 pairs of chromosomes (a total of 46) Very often embryos will have too many or too few chromosomes. These abnormalities are called aneuploidies.
She explained that even with genetically tested embryos, there is still a very small chance that the embryo was not healthy. Our embryo read healthy by the genetic testing reporting standards, but there is still a miscarriage rate of 5-10% in a PGD normal pregnancy.
It's true that there is some research showing that pregnancies conceived via in vitro fertilization (IVF) carry a slightly increased risk of miscarriage, compared with spontaneous (natural) pregnancies. 1 The exact level of the increased risk varies by study.
Recurrent early miscarriages (within the first trimester) are most commonly due to genetic or chromosomal problems of the embryo, with 50-80% of spontaneous losses having abnormal chromosomal number. Structural problems of the uterus can also play a role in early miscarriage.
Some women may be born with an irregularly shaped uterus, and some women may develop abnormalities with their uterus over time. A woman's immune system may also play a role in recurrent pregnancy loss. Hormone abnormalities may also impact pregnancy loss, including thyroid disease and diabetes.
Recurrent pregnancy loss can have a variety of causes including: Abnormalities in the uterus, such as a uterine septum, fibroids or retained pregnancy tissue. Cervical insufficiency, which causes losses late in pregnancy. Thyroid conditions, diabetes or high levels of the hormone prolactin.
Most fertility specialists believe that in more than 95% of IVF failures it is due to arrest of the embryos. Embryonic arrest is quite often due to chromosomal or other genetic abnormalities in those embryos that made them too “weak” to continue normal development and sustained implantation.
IVF can fail due to embryos that have chromosomal abnormalities. This means that the embryo has a missing, extra, or irregular portion of chromosomal DNA. The body then rejects the embryo and this results in IVF failure.
“Excellent” embryos had an 84.2% chance of ongoing pregnancy. “Good” embryos had a 61.8% chance of ongoing pregnancy. “Average” embryos had a 55.8% chance of ongoing pregnancy. “Poor” embryos had a 35.8% chance of ongoing pregnancy.
Higher quality embryos are associated with a 79% live birth rate with good quality at 64%. Poor quality embryos, however, are associated with a low birth rate of 28%. If you decide to have your embryos frozen or take part in a fresh embryo transfer below the age of 35, your chances of higher quality embryos increase.
According to one study, once a pregnancy gets past 6/7 weeks and has a heartbeat, the risk of having a miscarriage drops to around 10%.
The heavy use of alcohol or illicit drugs can also put you at higher risk of miscarriage. Uterine anatomical abnormalities- Women with abnormal uterus shape have a higher risk of first-trimester miscarriage compared to those with normal uterine anatomy.
If a miscarriage happens after the first trimester of pregnancy, it may be the result of things like an underlying health condition in the mother. These late miscarriages may also be caused by an infection around the baby, which leads to the bag of waters breaking before any pain or bleeding.
Patients often hear “PGS-normal embryos have a 60 – 70% success rate.” But that is on a per-transfer basis. Meaning that if you begin a cycle, retrieve eggs, produce embryos, then do PGS testing, and at least one embryo comes back normal, 60 – 70% of the time it will lead to a live birth.
“For most couples – and certainly those where the woman is younger than 40 and those of any age using donor eggs – two-thirds will achieve a live birth after five or six treatment cycles. This will take, on average, two years and is similar to rates that couples conceiving naturally take in one year.”
As you can see in the graph below, 48 per cent of women who were aged 30-31 when they started treatment had a baby after one stimulated cycle. This increased to 61 per cent after two cycles and 67 per cent after three cycles. This measurement is known as the 'cumulative live birth rate'.
“The most common reason that IVF fails across all ages is poor embryo quality due to poor egg quality.
For example, top quality embryos and blastocysts were sometimes genetically abnormal with the incidence of abnormalities as high as 50%, while poor grade embryos were characterized normal (12, 13, 19).
Studies show that women in their 20s and 30s have the most success when getting pregnant through IVF and other reproductive technologies. According to the CDC, the average percentages of assisted reproductive technology (ART) cycles that lead to a live birth are: 31% in women younger than 35 years of age.
Just 2 percent of pregnant women experience two pregnancy losses in a row, and only about 1 percent have three consecutive pregnancy losses. The risk of recurrence depends on many factors. After one miscarriage, the chance of a second miscarriage is about 14 to 21 percent.
In the United States, the most common recommendation was to wait three months for the uterus to heal and cycles to get back to normal. The World Health Organization has recommended six months, again to let the body heal.
For example, one 2005 study1 by British researchers found that the "time to pregnancy" was longer after a miscarriage, meaning it took longer for people who had a miscarriage to conceive again. In contrast, a 2003 study2 found higher odds of conception in the cycle immediately following an early pregnancy loss.