[Ten years of results of in-vitro fertilisation in the Netherlands 1996-2005].
To present the numbers and results of Dutch IVF treatment from 1996-2005 and to describe trends and differences between centres.
Retrospective data-collection, description and analysis.
The annual statistics from all Dutch IVF centres covering the years 1996-2005 were collected, described and analysed.
During this period 138,217 IVF or intracytoplasmic sperm injection (ICSI) cycles were started and 14,881 transfers of frozen-thawed embryos (cryo transfers) were performed. The number of ICSI treatments, in particular, increased to more than 6000 cycles during this period. These treatments resulted in 30,488 ongoing pregnancies (22.1% per cycle started; 19.1% for IVF and 23.4% for ICSI). The ongoing pregnancy rate per cycle increased from 17.6% in 1996 to 24.4% in 2005. The increase after cryo transfers was remarkable (from 9.4% to 17.6%). It is estimated that during this period, about 1 in 52 newborns in the Netherlands was an IVF or ICSI child (1996: 1 in 77, 2005: 1 in 43). There were differences between the individual centres regarding the ongoing pregnancy rate per cycle (range: 15.0-26.4%), the percentage of ICSI (range 20-58%), the percentage of cryo transfers per cycle (range: 4-22%) and the multiple pregnancy rate (range 5-27% in 2005).
In the Netherlands the pregnancy rate has increased over the last 10 years as has the number of IVF treatments. Cryo transfers have become increasingly important and the multiple pregnancy rate has decreased. Although thanks to the collaboration of all centres, the current registry produces important data and works well, there are a number of limitations e.g. the retrospective nature with no validation, which must be tackled over the coming years.
Available from: Fulco van der Veen
- "Currently, 1.2–2.3% of children born in the Western world are conceived by assisted reproductive technologies (Kremer et al., 2008; Wright et al., 2008). In the Netherlands, it has been estimated that the number of treatment cycles increased by 40% from 1996 till 2005 (Kremer et al., 2008). Fertility drugs (FDs) used in IVF treatment temporarily raise serum levels of exogenous gonadotrophins and gonadal hormones, and consequently increase the chances of multiple folliculogenesis and ovulations. "
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ABSTRACT: Long-term effects of ovarian stimulation for IVF on the risk of ovarian malignancies are unknown.
We identified a nationwide historic cohort of 19,146 women who received IVF treatment in the Netherlands between 1983 and 1995, and a comparison group of 6006 subfertile women not treated with IVF. In 1997-1999, data on reproductive risk factors were obtained from 65% of women and data on subfertility (treatment) were obtained from the medical records. The incidence of ovarian malignancies (including borderline ovarian tumours) through 2007 was assessed through linkage with disease registries. The risk of ovarian malignancies in the IVF group was compared with risks in the general population and the subfertile comparison group.
After a median follow-up of 14.7 years, the risk of borderline ovarian tumours was increased in the IVF group compared with the general population [standardized incidence ratio (SIR) = 1.76; 95% confidence interval (CI) = 1.16-2.56]. The overall SIR for invasive ovarian cancer was not significantly elevated, but increased with longer follow-up after first IVF (P = 0.02); the SIR was 3.54 (95% CI = 1.62-6.72) after 15 years. The risks of borderline ovarian tumours and of all ovarian malignancies combined in the IVF group were significantly increased compared with risks in the subfertile comparison group (hazard ratios = 4.23; 95% CI = 1.25-14.33 and 2.14; 95% CI = 1.07-4.25, respectively, adjusted for age, parity and subfertility cause).
Ovarian stimulation for IVF may increase the risk of ovarian malignancies, especially borderline ovarian tumours. More large cohort studies are needed to confirm these findings and to examine the effect of IVF treatment characteristics.
Available from: Meike Bartels
- "The first IVF treatment in the Netherlands was in 1983, and ICSI was introduced in 1994 . Nowadays, ICSI is often used simultaneously with IVF treatment . The introduction of ART was accompanied by an increase in the number of multiple births. "
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ABSTRACT: In a large set of twin pairs, we compared twins born after IVF to naturally conceived twins with respect to birth characteristics, growth, attainment of motor milestones, and emotional and behavioral problems. Twin families were registered with the Netherlands Twin Register. We included 1534 dizygotic (DZ) twins born after IVF, 5315 naturally conceived (NC) DZ twins, and 1504 control NC DZ twins who were matched to the IVF twins based on maternal age, maternal educational level, smoking during pregnancy, gestational age, and offspring sex. Data were obtained by longitudinal surveys sent to fathers, mothers, and teachers at ages 1, 2, 3, 7, 10, and 12 years. Results showed no differences in growth, in attainment of motor milestones, and in behavioral development between IVF and matched NC twins. It can be concluded that for nearly all aspects, development in IVF and NC children is similar.
Available from: humrep.oxfordjournals.org
- "Several validation studies have concluded that differences in pregnancy outcome rate between clinics have important limitations for the reproducibility of prediction models (Stolwijk et al., 1998; Smeenk et al., 2000; Hunault et al., 2007). By chance alone, pregnancy rates may vary from year to year and natural variation causes fluctuations in results (Kremer et al., 2008). In this paper, we intentionally avoided presenting performance data for centres, as league tables and control charts. "
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ABSTRACT: Pregnancy rates cannot be used reliably for comparison of IVF clinic performance because of differences in patients between clinics. We investigate if differences in pregnancy chance between IVF centres remain after adjustment for patient mix.
We prospectively collected IVF and ICSI treatment data from 11 out of 13 IVF centres in the Netherlands, between 2002 and 2004. Adjustment for sampling variation was made using a random effects model. A prognostic index for subfertility-related factors was used to adjust for differences in patient mix. The remaining variability between centres was split into random variation and true differences.
The crude 1-year ongoing pregnancy chance per centre differed by nearly a factor 3 between centres, with hazard ratios (HRs) of 0.48 (95% CI: 0.34-0.69) to 1.34 (95% CI: 1.18-1.51) compared with the mean 1-year ongoing pregnancy chance of all centres. After accounting for sampling variation, the difference shrank since HRs became 0.66 (95% CI: 0.51-0.85) to 1.28 (95% CI: 1.13-1.44). After adjustment for patient mix, the difference narrowed somewhat further to HRs of 0.74 (95% CI: 0.57-0.94) to 1.33 (95% CI: 1.20-1.48) and 17% of the variation between centres could be explained by patient mix. The 1-year cumulative ongoing pregnancy rate in the two most extreme centres was 36% and 55%.
Only a minor part of the differences in pregnancy chance between IVF centres is explained by patient mix. Further research is needed to elucidate the causes of the remaining differences.
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