13:39 16th November 2021 | Multiple Births
“Hello Doctor. My wife and I decided to come in for IVF because we plan to have twins. We only want two children and would rather have both at once, so we can move on to other plans. Besides, twins are so cute! And also, if we are paying so much for this procedure, we might as well have value for our money, yes?”
Many variations of this conversation occur in the consulting rooms of fertility doctors on a daily basis. In vitro fertilization (the process where the egg and sperm are united in the laboratory, allowed to progress as an embryo in the incubator for up to five days, before being returned to an expectant womb with the hopes of implantation) is now regarded as the magic wand for multiple pregnancies. These seem to be more desirable to a lot of couples in recent times, but might really just be for the optics.
Prior to in vivo (natural) conception, an egg is released from one ovary of most women at ovulation. This egg is met by sperm cells which have swum to the fallopian tube and one sperm fertilizes the egg. The cells in the fertilized egg start to multiply till they get to a more complex (blastocyst) stage where the embryo is ready to implant inside the uterus. This has about 25% chance of success per month in a young couple with no problems. In some cases, this single embryo splits and identical twins are formed. In other cases, two eggs are released and fertilized by two different sperm cells. If both embryos implant and progress, then non-identical twins are the result. Fun fact: the highest incidence of naturally conceived twin pregnancies worldwide is found among the Yorubas.
In the case of in vitro fertilization, one can determine how many embryos are replaced in the uterus after the eggs are fertilized. This increases, but does not guarantee, the chance of multiple pregnancy, as implantation of the embryo depends on a lot of complex factors. Considering the fact that each embryo can split, replacing more than one embryo in the uterus significantly increases the risk of higher order multiples.
Having siblings born on the same day is a very beautiful experience in pictures. However, it is important to note that multiple pregnancies are qualified as high risk, both for the mother and the fetuses. The mother has an increased risk of severe morning sickness, medical complications in pregnancy (such as hypertension, diabetes, anaemia and heart disease), miscarriage before 20 weeks, placental issues causing bleeding episodes, preterm delivery, Caesarean section, post-partum haemorrhage and maternal mortality. The fetuses have an increased risk of growth restriction in utero, twin to twin transfusion syndrome, low birth weight, prolonged NICU stay, and complications associated with prematurity. The high cost of raising multiples also comes to bear.
Many fertility associations worldwide now recommend transfer of a single embryo because of the progress made in the industry and for the sake of better health. Embryos are now cultured for longer in the laboratory. This allows you see which embryos survive past day 2 or 3 to day 5 or 6, as they are more likely to give you a healthy pregnancy. Advancements in embryo freezing, a process called vitrification, allows you preserve your spare embryos for future use without sacrificing, and maybe even improving, your pregnancy rates. Preimplantation Genetic Testing is another technique that uses the newest DNA sequencing techniques to allow you assess the number of chromosomes on the embryo and rule out some genetic disorders. This way, you can use a single embryo with full assurance of the genetic composition.
The main barrier to single embryo transfer seems to be cost. Many families cannot pay for multiple IVF cycles and would rather have multiple embryos transferred in a single cycle.
Priority needs to be placed more on quality over quantity: quality of life during pregnancy and the post-partum period for the mother and the children. This way, more families are complete and happy, one or two babies at a time.
Our free attendance forums are a great opportunity to speak to our fertility specialists and counsellors about overcoming conception challenges. Join us https://www.thebridgeclinic.com/patient-care/promotions-campaigns/welcome-forum to find out more.
Image credit: Google
By Dr Tambari Femi-Oluwole, Fertility Specialist
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