Multifetal pregnancy rates are reduced by a publicly funded in vitro fertilization (IVF) program requiring an elective single-embryo transfer (eSET) policy.
Takeaways
- Implementing a mandatory elective single-embryo transfer (eSET) policy in publicly funded in vitro fertilization (IVF) programs effectively reduces multifetal pregnancy rates, demonstrating a proactive approach to mitigate risks associated with assisted reproduction.
- The study reveals a substantial decline in multifetal pregnancy rates, particularly following IVF treatments, suggesting a positive impact of regulated eSET policies on pregnancy outcomes.
- While multifetal pregnancy rates were higher in patients undergoing ovulation induction or intrauterine insemination (OI/IUI) and IVF compared to unassisted conception, IVF showed a more pronounced decrease over time.
- Over the study period, there was a notable decrease in multifetal pregnancy rates for both OI/IUI and IVF treatments, indicating a potential shift towards safer reproductive practices.
- Despite the overall decline in multifetal pregnancy rates, there remains a need for increased attention to pregnancies resulting from OI/IUI, highlighting an area for further improvement in reproductive health strategies.
One in 6 couples worldwide are impacted by infertility. These patients are often given advanced fertility treatments, which allow conception but increase the risk of multifetal pregnancy. In Canada, approximately 1% to 2% of births occur through fertility treatments, and a multifetal pregnancy rate of 3.6% was reported between 2005 and 2014.
Following IVF, the rate of twins has been estimated as 17%, with the rate of higher-order multiple pregnancies estimated as 32%. As limiting the number of embryos transferred can reduce the rate of multifetal pregnancy, eSET has been recommended for patients with favorable pregnancy prognosis.
Within the first year following the implementation of a mandatory eSET program in Quebec, the rate of multifetal pregnancies decreased by 60%, indicating efficacy. However, pregnancy prevention is more difficult for ovulation induction or intrauterine insemination (OI/IUI), which have a multifetal pregnancy rate of 3% to 13%.
To evaluate the association between fertility treatment and multifetal pregnancy rates, investigators conducted a retrospective, population-based cohort study. Administrative health data was obtained and linked using maternal and child identifiers.
All live births and stillbirths in Ontario from April 1, 2006, to March 31, 2021, at 20 weeks’ gestation or later, along with fetal reductions, were included in the analysis. Data was evaluated by ICES, a nonprofit research institute with authorization to collect and use health care data for health system analysis, evaluation, and decision support.
The mode of conception was the primary exposure and included unassisted conception, OI/IUI, and IVF. Multifetal pregnancy was the primary outcome, reported as either twin or higher-order pregnancy. Covariates included maternal age at delivery, income quartile, parity, obesity, immigration status, chronic hypertension, and prepregnancy diabetes.
There were 1,724,899 pregnancies reported, 96.9% of which were by unassisted conception, 1.4% by OI/IUI, and 1.7% by IVF. The mean maternal age among patients with these conception methods were 30.6 years, 33.1 years, and 35.8 years, respectively.
Multifetal pregnancy was reported among 1.4% of births by unassisted conception, 10.5% by OI/IUI, and 15.5% by IVF. The adjusted relative risk (ARR) for multifetal pregnancy was 7 for OI/IUI and 9.9 for IVF when compared to unassisted conception.
From 2006 to 2021, the rates of multifetal pregnancy for OI/IUI and IVF decreased. The rates were 12.9% vs 9.1%, respectively, for OI/IUI, and 29.4% vs 7.1%, respectively, for IVF.
Twin pregnancy was reported in 1.4% of births by unassisted conception, 9.4% by OI/IUI, and 14.7% by IVF. The ARR of twin pregnancy was 6.4 for OI/IUI and 9.7 for IVF compared to unassisted conception. A decreased in twin pregnancy rates from 11% to 8.3% was observed between 2006 and 2021 for OI/IUI, vs from 27.6% to 8.8%, respectively, for IVF.
Higher-order multiple pregnancy was reported in 0.03% of births by unassisted conception, 1.2% by OI/IUI, and 0.8% by IVF, with ARRs of 29.1 and 19 for OI/IUI and IVF, respectively, vs unassisted conception. From 2006 to 2021, the rate decreased from 1.9% to 1% for OI/IUI and from 1.8% to 0.3% for IVF.
These results indicated a decrease in multifetal pregnancy risk after IVF following the implementation of a publicly funded IVF program in Ontario. Investigators concluded increased focus on OI/IUI pregnancies is necessary to further reduce multifetal pregnancy rates.
Reference
Velez MP, Soule A, Gaudet L, Pudwell J, Nguyen P, Ray JG. Multifetal pregnancy after implementation of a publicly funded fertility program. JAMA Netw Open. 2024;7(4):e248496. doi:10.1001/jamanetworkopen.2024.8496
