How Likely Are You to Miscarry When Going Through an IVF Treatment?
Recently, the Scottish First Minister Nicola Sturgeon spoke about her miscarriage in a book. Miscarriage is a loss of a pregnancy before it reaches the stage of viability. The limit of viability is considered as around 23 to 24 weeks. A naturally conceived pregnancy has almost one in six chance of miscarrying.
The vast majority of miscarriages occur before twelve weeks of pregnancy. After twelve weeks of pregnancy, the chance of miscarriage could be as low as three per cent. On the other hand, one percent of women may experience recurrent miscarriages. But, what is the risk of miscarriage for anyone going through an IVF or IVF/ICSI treatment? Also, are women with low ovarian reserves more likely to miscarry?
Before we go further, it is important to understand the cause of miscarriages. There are many reasons for miscarriages such as your age or genetic abnormality of embryo or fetus or a weak cervix ( cervical incompetence ). The vast majority of the miscarriages in the first twelve weeks occur because of genetic causes.
Almost two in three miscarriages at less than twelve weeks occur because of either too much genetic material or too little. Women at a later age are more likely to miscarry. With increasing age, there is a drop in the quality of the remaining eggs. This leads to a rise in the genetic errors during the division of the embryo cells resulting in the unequal splitting of the genetic material. This gives rise to a genetically abnormal embryo. Women trying to conceive at later ages may benefit from the preimplantation genetic screening (PGS) or comprehensive chromosome screening (CCS).
Another couple, who may have balanced translocation, is likely to pass on this abnormality to the embryo and give rise to either a balanced or unbalanced translocation. The carriers of balanced translocation may experience repeated pregnancy losses irrespective of age. This may occur when either woman or her partner carries balanced translocation. Such couple may benefit from preimplantation genetic diagnosis or PGD for chromosomal translocation.
Beyond the first three months of pregnancy, the chance of miscarriage drops to less than 3-5%. The miscarriages at this time of pregnancy are because of womb related causes such as cervical incompetence or weak cervix or septate uterus. Sometimes patients with antiphospholipid antibodies may experience later miscarriages may occur. In some women infections in the womb or genital tract can lead to pregnancy loss. Women with cervical incompetence are screened by measuring the length of the cervix or the neck of the womb. If this appears to be shortening, then your gynaecologist will discuss the option of placing a cervical stitch.
With infertility treatments such as IVF, it is believed that the risk of miscarriage is higher than in natural conception. An interesting study published a few years ago looked into a large data of over 750,000 women. These women went through IVF or IVF / ICSI treatment in the UK between 1991 and 2008. Researchers wanted to answer the question, do women with low ovarian reserve may have a higher risk of miscarriage? Also, can we better predict women with low ovarian reserves? This information will be helpful in helping patients make informed choices about their treatment.
The study showed that women who had three or fewer eggs collected can be considered as having low ovarian reserve. This information should be interpreted along with the other tests for ovarian reserve such as anti-mullerian hormone or AMH, Follicle-stimulating Hormone or FSH and antral follicle count or AFC. It appears that the risk of miscarriage increases with female age and with depletion of ovarian reserve.
Women who are less than thirty-five years of age with good ovarian reserve are not at an increased risk of miscarrying compared to women who conceive naturally. However, even women with low ovarian reserve who had three or fewer eggs collected are at an increased risk of miscarriage. The chance of miscarriage for those less than thirty-five is 18%. This rises to 23% in women between thirty-five and thirty-seven years. And, it further rises to 30% in women thirty-eight to thirty-nine years of age. Women between forty and forty-two years of age have almost 40% risk of miscarrying after IVF or IVF/ICSI treatment. Women over forty-five years have a 65% or two in three chance of miscarrying if conceived following fertility treatment. It appears that the incidence of miscarriage has not changed over the last two to three decades.
Miscarriage or pregnancy loss is a distressing situation for couples. Couples with implantation failure or miscarriages or combination of implantation failure and miscarriage will benefit from detailed investigations to understand potential cause of miscarriage. In some cases, there may not be any identifiable reasons. Some couples will benefit from interventions such as preimplantation genetic screening or certain supplementary medicine. In others with the age-related occurrence of miscarriage, treatment with egg donation may be considered. So, detailed personalised assessment on a case by case basis is important. But, what is vitally important that all couples are offered counselling support during treatment or in pregnancy.