Multiple gestation after IVF – One embryo at a time…?
For these reasons, practitioners of in vitro fertilisation, as well as the patients themselves, prefer the transfer of more than a single embryo per transfer.
This unfortunately leads to a second aspect of in vitro fertilisation – the occurrence of multiple gestation.
How much of a problem is multiple gestation
Multiple gestation occurs when more than 1 embryo implants into the uterus. In nature, 1 in 80 (1.3%) of pregnancies are twins. In assisted reproduction, the figure is as high as 20%.
|Incidence of multiple gestation after IVF|
Occasionally, even a single embryo can give rise to a multiple gestation: this is the case for identical twins but is an uncontrollable circumstance and so cannot be avoided. Therefore, usually, multiple gestation occurs after assisted reproduction and is ‘induced’ through the transfer of more than 1 embryo.
Many patients relish having twins at a single blow. They feel it is ‘value for money’ or creating a family all in one blow. Gynecologists and obsteticians are a little more cautious for the following reasons:
|Common risks of multiple gestation after IVF|
|Risks to the mother||Risks for the unborn|
|Singleton||5% risk of preterm birth6% risk of preeclampsia2% risk gestational diabetes||0.3% risk of death within 1 month0.17% risk cerebal palsy|
|Twin||60% risk of preterm birth10-15% risk of pre-eclampsiaGestational diabetes||Growth restriction after 30 weeksLow birth weight1% risk death within 1 month
0.62% risk cerebral palsy
|Triplet||90% risk of preterm birthTriple risk of pre-eclampsiaGestational diabetes||Growth restriction after 27 weeksLow birth weight2% risk of death within 1 month|
American Pregnancy Association
In essence, a multiple birth is risky to the mother and unborn child, and could affect the formation of a healthy family.
This is why governments have felt the need to limit the number of embryos that can be legally replaced into the uterus during IVF, and organisations such as the HFEA are carrying out a policy to limit the number of multiple births (such as the One at a time program).