In a natural pregnancy, if 100 couples conceive 15 to 20 of them lose the pregnancy. Abortion happens for various reasons. The most common cause for abortion in a woman who conceives normally is an abnormal genetic material also known as aneuploidy. It is nature’s quality control to prevent an abnormal pregnancy or abnormal baby from coming into this world. The negative consequences of it when nature does its quality control job we are unhappy but if it fails to do quality control and have an abnormal pregnancy or an abnormal child again we are unhappy.
The reality is, nature plays a role in IVF also similarly. An embryo in an IVF lab can look normal but it has to implant and further progress for 14 more days for a positive pregnancy test. It should further progress for two weeks before we see in ultrasound and then progress for 8-10 weeks more to make out abnormalities. To a large extent, a pregnancy loss happens with a blood test positive but the scan does not show anything. It can be called a biochemical pregnancy loss. When the ultrasound shows a pregnancy that is inappropriate to the duration and with no formation of fetus we say a blighted ovum.
The other category is the formation of the heartbeat which subsequently stops which is called a fetal demise. A pregnancy loss can be due to various reasons. In an IVF pregnancy earlier people used to think it reduces the abortion rate, but the answer is whatever happens in a natural pregnancy all rules apply to an IVF pregnancy, be it abortions, be it abnormalities, be it hypertension in the mother or, pregnancy-induced diabetes in the mother or bigger babies or smaller babies whatever applies to a normal pregnancy will happen in IVF pregnancy also.
It is on the higher side because here you are treating a failure of nature to produce a natural pregnancy. In a normal pregnancy, nature is playing its role of quality control but here you are trying to disturb a situation where nature does not want the pregnancy to happen. When we are trying to correct it and still nature protects it what are the current ways of avoiding that situation.
One is pre-pregnancy evaluation. It is important to have optimal health before planning a pregnancy. the second is the precautions for the male in terms of health weight diabetes smoking alcohol. In the woman similarly smoking alcohol control of weight and healthy pre-pregnancy nutrition will minimize some problems to a certain extent and during the transfer of the embryo, certain embryo selection methods possibly reduce but do not eliminate abortions.
The current technologies in those areas are time-lapse embryo monitoring and pre-implantation genetic diagnosis or embryo biopsy to rule out any chromosome abnormality and then transfer those embryos selectively. Even this reduces the chance of miscarriage but does not eliminate a pregnancy loss. Any couple who are planning an IVF should also anticipate the possibility of a miscarriage so IVF is not an assurance that you will hundred percent have a baby.
Even if you’re pregnant it does not mean all IVF pregnancies will end up in a live birth so there is a new definition that is coming in where a clinic should say what is a live birth rate and it is a better indicator of quality control of that clinic and what is the miscarriage rate, preterm delivery rate, and the other complications. A lot of clinics can say I have a 70% pregnancy rate but that can mean only HCG value. One should always ask what do they mean by pregnancy rate and another term is an ongoing pregnancy rate but finally, the most important is the live birth rate per started cycle which is the ultimate thing that defines the quality of the clinic.