Articles Follow-up of children born after assisted reproductive technologies

RBMOnline - Vol 5. No 3. 317 322 Reproductive BioMedicine Online; www.rbmonline.com/article/669 on web 9 August 2002 Articles Follow-up of children born after assisted reproductive technologies Dr Michael Ludwig was born in 1968 in Germany and concluded university in 1994. He is Gynaecologist and Obstetrician at the University Hospital Lübeck and is running the Division of Reproductive Medicine and Gynaecologic Endocrinology at the Department of Gynaecology and Obstetrics. Dr Ludwig has published several papers in different fields of reproductive medicine, especially assisted reproductive techniques. His special interests lie in the field of evidence-based reproductive medicine and epidemiological studies in assisted reproductive treatment. Dr M Ludwig Michael Ludwig 1, Klaus Diedrich Department of Gynecology and Obstetrics, University Clinic, Ratzeburger Allee 160, 23538 Lübeck, Germany 1 Correspondence: Tel: +49 451 500 2158; Fax: +49 (0) 451 5059334; e-mail: Ludwig_M@t-online.de Abstract The course of pregnancies and the health of children born after assisted reproductive technologies are two of the most important outcome parameters of the quality of the techniques. There is an ongoing discussion as to whether these parameters may show poorer results as compared with spontaneous conception. Recent studies have shown increased risks for the pregnancy course following conventional IVF (e.g. premature birth, low birthweight), and a higher rate of major malformations after conventional IVF as well as after intracytoplasmic sperm injection. Molecular biological studies may support the idea that these risks are not related to the techniques used, but to parental background factors. Data from surrogate motherhood also demonstrate that here the risk is lower as compared with pregnancies from IVF mothers, who carry their own child to birth. Therefore, there are more infertility related problems than those related to technique. Finally, however, a risk related to the technique itself cannot be excluded completely by currently available data. Keywords: assisted reproductive technologies, congenital malformation, ICSI, IVF Introduction For as long as assisted reproductive technologies have been used, there has been an ongoing discussion as to whether there might be an impact on pregnancy course and especially on the health of children born after those procedures. Until recently, however, the general agreement was that there is no worse outcome of children born following conventional IVF, but that there might be an effect on the health of children born after intracytoplasmic sperm injection (ICSI). The latter seemed to be concentrated on the incidence of chromosomal abnormalities in fetuses and babies born following this procedure (Bonduelle et al., 1998). On the other hand, most studies carried out on children born following conventional IVF were done on a non-controlled, observational basis. Therefore, hard data on the health of these children are based on only a few, recently published studies. Using new data on this topic, this paper tries to give an overview and discussion that may shed light on some points, but also will show which questions have to be addressed in the future. Pregnancy follow-up following conventional IVF The problem of a higher incidence of pregnancy complications became evident in the mid-1980s (Lancaster, 1985). At that time, it had already been considered that certain characteristics of the parents themselves, e.g. the greater age of the mother, would contribute to this risk. However, even after matching for gestational age, parity and maternal age, a higher risk of gestational diabetes and pregnancy-induced hypertension was reported in a recent study (Maman et al., 1998). In a study from Sweden, these risks could not be confirmed for singleton pregnancies following IVF; however, there was a significantly higher rate of premature birth after matching for maternal age, parity, height, weight, ethnic origin, smoking habit, medical disorders, and obstetric history (Koudstaal et al., 2000). Several controlled studies have been done in singleton pregnancies after conventional IVF, all of which have shown consistent results in one point; that there is a higher incidence of pregnancy complications compared with spontaneously conceived children (Doyle et al., 1992; Petersen et al., 1995; 317

D Souza et al., 1997; Bergh et al., 1999). The most consistent finding was a higher prematurity rate and a higher rate of low birth weight. Recently, a study by Schieve et al. from the United States has reported similar findings (Schieve et al., 2002). In this study, 42,463 children born after assisted reproductive technology in the years 1996 and 1997 were compared with 3,389,098 naturally conceived children born in 1997. Assisted reproductive technology in this study was defined by all procedures in which oocytes and spermatozoa were handled outside the body, i.e. conventional IVF, ICSI, GIFT (gamete intra-fallopian transfer), cryopreservation cycles and donor oocyte or embryo cycles. In the study cohort, 43% of children were singletons, 43% were twins, 12% were triplets and 1% were quadruplets or higher order multiples. Looking at all children born, there was a higher rate of low birth weight (<2500 g) in the group of triplets (92.4%) as compared with twins (55.2%), and singletons (13.2%). When only the 16,730 singletons in the study group after adjustment for mother s age were analysed, there was a significantly increased risk for low (relative risk 1.8, 95% confidence interval (CI) 1.7 1.8) and very low birth weight (relative risk 1.7, 95% CI 1.5 1.9). These results are also shown in Table 1. These data confirm that the main risk of prematurity is due to the multiple pregnancy rate, but there remains a risk of low birth weight and very low birth weight, even when only singletons are analysed. The presence or absence of a male factor seems not to have an impact in this study. In parallel, another study showed the problem of multiple pregnancies with regard to children s health (Strömberg et al., 2002). This group from Sweden demonstrated in a register based study that the risk for neurological sequelae in children born after IVF was 1.4 times higher as compared with spontaneously conceived children. In their study, the authors included a group of 5680 children born after IVF, and 11,360 matched controls. For the 2060 twins in the IVF group, a second control group of 4120 spontaneously conceived twins was chosen. The neurological performance was studied using data from the Swedish habilitation centres. Stratification for the controls was performed for sex, year of birth and birth hospital. The risk to get in contact with a childhood disability centre was 1.7 (95% CI 1.3 2.2) for all IVF children as compared with controls (2% versus 1%). For singletons the risk was 1.4 (95% CI 1.0 2.1) (1.4% versus 1.0%). After performing a logistic regression analysis, only gestational age and birthweight had a significant influence on the risk of getting in contact with a childhood disability centre, but a history of IVF, maternal age <30 or >35 years, or male sex did not. The most substantial risk for cerebral palsy in this analysis in singletons also was low birth weight (12.4, 95% CI 5.2 29.3) and low gestational age (5.5, 95% CI 2.3 13.3); IVF was not a significant risk factor. Therefore, the conclusion was that it is largely the high number of multiple births that leads to the increase in risk of neurological problems in these children, and not the IVF procedure itself (Strömberg et al., 2002). On the other hand, again the previously described risk of having low birth weight and being born premature might influence this risk especially in the IVF cohort. Finally, another group from Sweden showed that it is also mainly the rate of multiple pregnancies which contributes to a higher number of hospital stays in children born after IVF (Ericson et al., 2002). Very interestingly, the above-cited study by Schieve et al. also included a group of surrogate mothers, not suffering from infertility, but treated by IVF to carry the child of another couple (Schieve et al., 2002). In this group, there was no increased risk, either for low or very low birthweight (Table 1). This confirms that it is not a procedure, but an infertility related risk, which contributes to the higher prematurity rate. Table 1. Results of a retrospective, register-based analysis of singleton births following assisted reproductive technology in the United States (adapted from Schieve et al., 2002). Outcome parameter Total number Number of cases Standardized risk observed ratio (95% CI) Low birth weight (<2500 g) All infants 18,398 2423 1.8 (1.7 1.9) Pregnancies with one fetal heart 16,730 2104 1.8 (1.7 1.8) Use of donor oocytes, 1397 190 1.6 (1.4 1.8) no male factor infertility Diagnosis of male factor infertility 2795 329 1.7 (1.5 1.9) Use of gestational carrier 180 16 1.2 (0.6 1.8) Very low birth weight (<1500 g) 318 All infants 18,398 480 1.8 (1.7 2.0) Pregnancies with one fetal heart 16,730 408 1.7 (1.5 1.9) Use of donor oocytes, 1397 49 2.1 (1.5 2.7) no male factor infertility Diagnosis of male factor infertility 2795 78 2.0 (1.6 2.5) Use of gestational carrier 180 0

Others have shown a similar infertility related risk before. Pandian et al. (2001) have demonstrated that women suffering from idiopathic infertility show an increased risk of preeclampsia, placental abruption, premature delivery and emergency Caesarean section. All these risks were independent from treatment-induced pregnancies or spontaneous pregnancies. Therefore, the authors concluded for this special group of patients, that infertility treatment per se does not increase either the complication rate or the rate of intervention in these women. To conclude for this point, pregnancies following an IVF procedure seem to be at a higher risk for pregnancy complication and premature birth. This risk is largely due to the higher rate of multiple pregnancies, but there remains a risk related only to the infertility of the mothers. Regarding neurological problems, no higher risk is associated with the IVF procedure itself. Malformation risk in children born after conventional IVF and ICSI It has been an accepted fact in the past, that children born following conventional IVF do not have an increased risk of congenital malformations. Looking through the literature, there are, however, only a small number of controlled studies, which have addressed this topic. Recently, a study published in the New England Journal of Medicine has shown an increased risk of congenital malformations in IVF as well as in ICSI children (Table 2) (Hansen et al., 2002). Table 2. Risk of major malformations in children born after conventional IVF or ICSI in Western Australia as compared with spontaneously conceived children. Results of a retrospective, register based analysis. Shown are the data regarding pregnancy outcome (singletons only) in the three studied cohorts (a) as well as the relative risk for a major malformation (b) (adapted from Hansen et al., 2002). (a) Outcome parameter ICSI P-value a IVF P-value a Natural conception Stillborn n (%) 0 6 (1) 25 (1) Birth weight (g) 3271 ± 552 0.02 3182 ± 686 <0.001 3368 ± 571 Preterm delivery (<37 week of 16 (9) 73 (14) 0.001 225 (6) gestation) n (%) Low birth weight (<2500 g) n (%) 12 (6) 38 (7) 0.002 163 (4) Very low birth weight (<1500g) n (%) 2 (1) 19 (4) <0.001 41 (1) Gestational age (weeks) 38.6 ± 2.2 38.0 ± 3.0 0.03 39.1 ± 2.0 Values are mean ± SD, if not otherwise defined. a In relation to natural conception. (b) Group Children (n) Prevalence of Adjusted odds major malformation ratio (95% CI) All infants Natural conception 4000 168 (4.2) 1.0 ICSI 301 26 (8.6) 2.0 (1.3 3.2) IVF 837 75 (9.0) 2.0 (1.5 2.9) All singletons Natural conception 3906 164 (4.2) 1.0 ICSI 186 18 (9.7) 2.2 (1.3 3.9) IVF 527 50 (9.5) 2.2 (1.5 3.2) Term singletons Natural conception 3681 149 (4.0) 1.0 ICSI 170 15 (8.8) 2.2 (1.2 4.0) IVF 454 38 (8.4) 2.1 (1.4 3.2) 319

320 In this study 301 infants conceived with ICSI, 837 infants conceived with conventional IVF, and 4000 spontaneously conceived children were compared. Risk factors in the parents included a higher maternal age, and a lower incidence of having had a child previously. Regarding pregnancy outcome, i.e. gestational age, premature birth rate, low and very low birth weight, there were again significant differences for IVF as compared with naturally conceived children (Table 2). The risk of having a major malformation was significantly increased by 2-fold, independent of whether conventional IVF or ICSI was performed. To exclude a reporting bias, i.e. to over-report malformations in the cohorts of children conceived by assisted reproductive technology directly after birth, the authors looked for registered malformations up to 1 year of age. These data are based on a large cohort of spontaneously conceived children and several hundred children conceived after assisted reproductive technology. Of course, there are studies based on a higher number of infants (e.g. Bonduelle et al., 2002), but it is unlikely that the study results would change if a higher number of children were included. It may be a major drawback that this study was done retrospectively. It is impossible to exclude a reporting bias for the different cohorts, especially since reports from Australia in the past have proposed a higher risk for children conceived by ICSI (Kurinczuk and Bower, 1997), and therefore paediatricians may have been more likely to report any malformation to the registers. Another drawback is that an adjustment could be made for only for a limited number of background risk factors of the parents, since only a limited number of those factors were collected in the register based data set. However, we may assume, that even by this the relative risk might decrease but will not disappear totally. It has recently been shown in a prospective controlled study in a cohort of 3372 fetuses and infants conceived by ICSI, that the risk for a major malformation was increased by 1.25-fold (95% CI 1.10 1.46) (see Table 3, repeated from Ludwig and Katalinic, 2002). The risk for children born after ICSI was exactly the same as that described by Henson et al. (2002). The Table 3. Risk of having a major malformation. Data from a prospective, controlled study including fetuses and infants from pregnancies after ICSI as compared with spontaneous conception. All pregnancies were analysed, which ended after week 16 of gestation by spontaneous abortion, induced abortion, stillbirth or livebirth (see Ludwig and Katalinic, 2002) a. ICSI cohort (n) RR (95% CI) Malformation rate 8.6 (291/3372) 1.25 (1.10 1.46) (total) (%) Origin of spermatozoa b Ejaculated 8.4 (248/2944) 1.0 Testicular 9.2 (21/229) 0.92 (0.60 1.41) Epididymal 3.8 (1/26) 2.19 (0.32 15.02) a Table previously published (Ludwig et al., 2002) and reprinted with permission. b Information not available for 173 children/fetuses. risk did not depend on the origin of spermatozoa in the ejaculate. Bonduelle et al. may have carried out the largest prospective, controlled cohort study, which compared pregnancies conceived after IVF to those conceived after ICSI (Bonduelle et al., 2002). In the most recent analysis, they reported on a cohort of 2889 infants born after ICSI and 2995 infants born after IVF. The results of this study are summarized in Table 4. There were no significant differences regarding pregnancy outcome parameters, and especially no differences regarding the major malformation rates. The data from this study do not contradict the results of the Western Australian study (Hansen et al., 2002), since the malformation rate was similar between IVF and ICSI children, but no control group of spontaneously conceived children was included. Two other recently published studies have also contributed this discussion (Wennerholm et al., 2000; Ericson and Kallen, 2001). Both studies have described a significant increase in the malformation rate following ICSI. This was, however, not found after adjustment of background risk factors (Table 5). The only malformation, that was still found to be increased following ICSI in both analyses was the risk for hypospadias. This was thought by the authors to be related to genetic factors causing male factor infertility. Finally, there remains the possibility of a higher incidence of gonosomal abnormalities in children born after ICSI (Bonduelle et al., 1998). Here, the risk was said to be increased from ~0.2% to ~0.8%. In a more recent analysis of the same group in a larger cohort of children, the risk in children born after ICSI had decreased to 0.63% but was still increased as compared with naturally conceived children (Bonduelle et al., 2002). There is an ongoing debate as to whether these differences are related to ICSI itself or are related to genetic abnormalities in the spermatozoa of men suffering from male subfertility. In two recent reviews, different possibilities, molecular-biological findings and theories have been discussed (Ludwig et al., 2001; Schröder et al., 2001). It was concluded that it is unlikely that ICSI contributes to this abnormality, but rather that parental background risk factors are responsible. Furthermore, a recent publication has confirmed that paternal genetic abnormalities in spermatozoa are a more likely cause of genetic abnormalities in the offspring than the ICSI technique itself (Sbracia et al., 2002). Conclusion There is increasing evidence that pregnancies following conventional IVF show more complications than those after spontaneous conception. It is still uncertain if this is also true of pregnancies resulting from ICSI. Data from surrogate pregnancies, however, show, that the risks following conventional IVF seem not to be linked to the assisted reproductive technology procedure, but to risk factors of the infertile mothers, since, e.g. the risk of premature birth and low birthweight is not increased in the pregnancies of surrogate mothers.

Table 4. Results of a prospective, controlled study comparing infants born after ICSI to those born after conventional IVF. Pregnancy follow-up and examination of children was performed according to a standardized procedure (adapted from Bonduelle et al., 2002). Outcome parameter ICSI IVF P-value Infants (n) 2889 2995 Stillbirths n (%) 49 (1.7) 40 (1.3) NS Gestational age (weeks) 37.9 ± 2.6 37.9 ± 2.8 NS Birthweight (g) Total group 2806 ± 719 2765 ± 725 NS Singletons 3224 ± 581 3176 ± 582 NS Twins 2394 ± 522 2382 ± 560 NS Triplets 1761 ± 548 1768 ± 497 NS Birthweight <2500 g (only singletons) n (%) 106 (7.1) 121 (7.8) NS Birthweight <1500 g (only singletons) n (%) 22 (1.5) 28 (1.8) NS Prematurity (<37 weeks of gestation) (only singletons) n (%) 126 (8.4) 140 (9.0) NS Admission to neonatal unit (only singletons) n (%) 261 (17.5) 289 (18.7) NS Major malformation n (%) 122/2889 (4.22) 135/2895 (4.66) NS NS = no significant difference. Table 5. Malformation risk following ICSI in two Swedish studies. After adjustment for background risk factors, there was only a risk left for the prevalence of hypospadias. Shown are relative risks (95% confidence intervals). Adapted from Wennerholm et al. (2000) and Ericson and Källen (2001). Analysis of data from the Swedish Medical Birth Registry and Registry of Congenital Malformation (n = 1139) (Wennerholm et al., 2000) Risk for major malformation 1.75 (1.19 2.58) a after ICSI After stratification for multiples 1.19 (0.79 1.81) Hypospadias 3.0 (1.09 6.50) Analysis of data from the Swedish Medical Birth Registry and Registry of Congenital Malformation for all IVF births (n = 9175) (Ericson and Källén, 2001) Risk for major malformation after ICSI 1.47 (1.34 1.61) b After stratification 0.89 (0.74 1.06) c Hypospadias (only ICSI) 1.36 (1.19 1.56) a Adjusted for: year of birth, delivery hospital, maternal age. b Adjusted for: year of birth. c Adjusted also for: maternal age and parity, number in birth, multiples, time of involuntary childlessness. Regarding malformation rates, the risk of genetic abnormalities is increased after ICSI. This is in part due to known chromosome abnormalities, especially in the fathers. On the other hand, even without chromosome abnormalities in the parents, more gonosomal abnormalities are found in the offspring. Here, genetic factors, such as a higher rate of gonosomal aberrations in spermatozoa, might be responsible. Also, the risk of major malformation in general seems to be higher in pregnancies after ICSI as compared with those after spontaneous conception. It seems unlikely that this is due to the procedure itself, although this cannot definitely be excluded. Again, parental factors, especially of genetic origin, seem to be a major factor. Future studies will prove whether this risk can be attributed to a more narrowly defined group of patients, and whether this risk is also apparent for pregnancies following conventional IVF. An ideal study to address the question of congenital malformation could be done by prospectively randomizing patients who have an indication to be treated by IVF to either conventional IVF or ICSI. Children would have to be evaluated by a standardized procedure, including sonography of hips and kidneys and echocardiography in case of clinical abnormalities. This should be done by a small group of neonatologists, who are unaware of the assisted reproductive technology procedure used. Since it is unethical to randomize fertile patients for the assisted reproductive technology procedures, it is difficult to include a real control group. Perhaps a second group should be randomized, consisting of surrogate mothers. Finally, a group of spontaneously 321

322 conceived children should be evaluated according to the same procedure as the children born after assisted reproductive technology. Until that time, parents should be counselled that a techniquerelated risk cannot be excluded totally. Since this paper was originally drafted, two ICSI children have been born with Angelman s syndrome (Cox et al., 2002). This raises the possibility of ICSI disturbing epigenetic processes occurring at fertilization (Arney et al., 2002). Although this case report alone is insufficient to claim this as fact, it provides further support for the view that the health of children born by assisted reproductive technology procedures should be closely monitored, particularly for those syndromes and malformations that are known to be the result of imprinting errors. References Arney RL, Bao S, Bannister AJ et al. 2002 Histone methylation defines epigenetic asymmetry in the mouse zygote. International Journal of Developmental Biology 46, 317 320. 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