Rates of Chromosomal Anomalies in Children Conceived after Assisted Reproductive Techniqes
Background. Despite doubts about safety of in vitro fertilisation-embryo transfer (IVF-ET), intracytoplasmic sperm injection (ICSI) and use of frozen embryos, statistical analyses up to date have shown that risk of congenital malfomations is not essentially different from the risk in case of natural conception. The only fact that was shown is that in neonates born after ICSI procedure, abnormalities of sex chromosomes were present more often. Risk factors of sterile couples are: their age, sterility and frequent multiple pregnancies. An assessment of prevalence and distribution of chromosomal and structural malformations in our country would be useful in treating the sterile couples in the future.
Aim and hypothesis. The aim of the survey is to determine whether rates of congenital malformations in neonates born after assisted reproductive techniques are higher than in neonates born after a spontaneous conception.
Patients and methods. 242,164 neonates born to 241,607 mothers from April 1987 to December 1997 in Slovenia, were included in retrospective survey. The survey was divided into 3 cohort and 1 case-controlled studies. In first two studies prevalence of chromosomal, structural and lethal abnormalities were observed. In first study we compared 1404 neonates born after IVF-ET procedure with neonates born after spontaneous conception. In second controlled study we compared 1270 neonates born after IVF-ET procedure with 1270 neonates born after spontaneous conception, whose mothers were matched according to their age, multiplicity, parity and year of birth. In third study we observing the shares of congenital abnormality rates according to a form of fertilisation. We compared 73 neonates with congenital abnormalities, born after IVF-ET procedure with 9685 neonates with congenital abnormalities, born after spontaneous conception. In the fourth study we were assessing possible risk factors (age, multiplicity, parity and ICSI procedure). We compared 54 mothers of neonates with congenital malformations with 1048 mothers of neonates without congenital malformations born after IVF-ET procedure. Data of neonate born after frozen embryo transfer was analysed in descriptive manner. Results were statistically evaluated by χ² test for non-parametrical variables and t-test for parametrical variables.
Results. More lethal, respiratory, cardiovascular malformations and less locomotor system malformations were found in neonates conceived after assisted reproductive techniques than in neonates of general population. No differences between the two groups of neonates were found after matching their mothers according to age, multiplicity, parity and year of birth. In the group of neonates with congenital abnormalities we found bigger share of lethal and cardiovascular malformations and smaller share of locomotor malformation in the group of neonates conceived after assisted reproductive techniques than in the group of neonates born after spontaneous conception. In comparison of mothers treated with assisted reprodutive techniques whose neonates were born with congenital abnormalities and those treated mothers whose neonates had any congenital abnormalities we found no significant risk factors. In neonates born after ICSI we found only four minor abnormalities.
Conclusions. We established that assisted reproductive techniques do not raise congenital abnormality rates. We established higher share of cardiovascular abnormalities among all congenital abnormalities after assisted conception. ICSI procedure is not a risk factor for birth of abnormal neonate to mothers treated with assisted reproductive techniques.