Risk of small for gestational age is reduced after frozen compared with fresh embryo transfer in endometriosis

IVF/ICSI Outcomes After a Freeze-All Strategy: an Observational Cohort Study

In order to inform patients undergoing ART regarding their chances for motherhood, it seems useful to describe "freeze all" outcomes according to the different potential indications. The goal of this study was to examine the impact of a "freeze-all approach" on the cumulative live birth rate (cLBR) according to the indication. It is a cohort study including women who had undergone ovarian stimulation (OS) using an antagonist protocol with GnRH agonist triggering between 09.2016 and 09.2018 followed by a freeze-all cycle of blastocyst embryos. The ART outcomes were compared between the two main indications of the freeze-all strategy which were in our cohort: risk of ovarian hyperstimulation syndrome (OHSS) and endometriosis. The ART outcomes were also described for the others indications (inadequate endometrium and/or premature progesterone elevation at trigger day, two or more previous ART failures, and autoimmune disease and/or a high risk of thromboembolic disease (AI and/or TE risk)). In total, 658 women were included. The cLBR in the total population was 37.7% (248/658). The cLBR was significantly higher in the "OHSS risk" group (133/281, 47.3%) than in the "endometriosis" group (69/190, 36.3%) (p = 0.017). No significant differences were noted regarding perinatal outcomes, except a significantly higher risk of placenta praevia (PP) observed in the "endometriosis" group (10.1%) (p = 0.002). The "freeze-all approach" yielded good results in terms of the cLBR and especially in case of OHSS risk. These data should be taken into account when informing patients about the ART strategy and their chances of motherhood.

Cardiovascular function in 8- to 9-year-old singletons born after ART with frozen and fresh embryo transfer

STUDY QUESTION

Do 8- to 9-year-old singletons conceived after frozen embryo transfer (FET) or fresh embryo transfer (Fresh-ET) have increased arterial stiffness compared to naturally conceived (NC) children?

SUMMARY ANSWER

The process of FET or Fresh-ET is not associated with altered cardiovascular function in 8- to 9-year-old singletons, including arterial stiffness, as compared to NC children.

WHAT IS KNOWN ALREADY

ART has been suggested to influence cardiovascular risk factors (i.e. endothelial dysfunction, increased arterial blood pressure and insulin resistance). It is not known if ART procedures alter arterial stiffness in singletons.

STUDY DESIGN, SIZE, DURATION

A cohort study was carried out, including 8- to 9-year-old singletons conceived after FET, Fresh-ET and NC children (50 children in each group). This study was conducted between November 2018 and August 2020.

PARTICIPANTS/MATERIALS, SETTING, METHODS

In total, 150 singletons were identified through the Danish IVF Registry and the Medical Birth Registry. They underwent cardiac magnetic resonance imaging (CMR) and anthropometric measurements. Parental data were collected using questionnaires. NC children were matched by sex and birth year with FET/Fresh-ET children. Exclusion criteria were congenital heart disease, maternal gestational diabetes or maternal diabetes mellitus. Our primary outcome was arterial stiffness, which is assessed from noninvasive arterial blood pressure and aortic ascendens distensibility. The secondary outcome was the pulse wave velocity of total aorta and exploratory outcomes were left ventricular ejection fraction, mean arterial pressure, cardiac output and total peripheral resistance. Measurements and analyses were performed blinded to the child group.

MAIN RESULTS AND THE ROLE OF CHANCE

Aortic ascendens distensibility of children conceived after FET and Fresh-ET did not differ from NC children (mean (SD): FET 11.1 (3.6) 10-3 mmHg-1, Fresh-ET 11.8 (3.0) 10-3 mmHg-1, NC 11.4 (2.8) 10-3 mmHg-1, P > 0.05). Multivariate linear regression was performed to adjust for potential confounders (i.e. child sex and age, maternal BMI at early pregnancy and maternal educational level). Data showed no statistically significant differences between study groups and aortic ascendens distensibility. However, the fully adjusted model showed a non-significant tendency of lowered aortic ascendens distensibility in children born after FET compared to Fresh-ET (β estimate (95% CI): -0.99 10-3 mmHg-1 (-2.20; 0.21)) and NC children (β estimate (95% CI): -0.77 10-3 mmHg-1 (-1.98; 0.44)). Lastly, secondary and exploratory outcomes did not differ between the groups. Primary and secondary outcomes showed good intra-rater reliability.

LIMITATIONS, REASONS FOR CAUTION

This study is possibly limited by potential selection bias as the participation rate was higher in the ART compared to the NC group. Also, in some variables, the study groups differed slightly from the non-participant population. The non-participant population (n = 1770) included those who were excluded, not invited to CMR scan, or declined to participate in this study.

WIDER IMPLICATIONS OF THE FINDINGS

Our findings indicate that children born after FET or Fresh-ET do not have altered cardiovascular function, including arterial stiffness. This is reassuring for the future use of ART.

STUDY FUNDING/COMPETING INTEREST(S)

This study was funded by the Novo Nordisk Foundation (grant reference number: NNF19OC0054340) and The Research Foundation of Rigshospitalet. All authors declared no conflict of interests.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov identifier: NCT03719703.

Infertility treatment and the risk of small for gestational age births: a population-based study in the United States

Objective

To evaluate the association between infertility treatments and small for gestational age (SGA) births.

Design

Cross-sectional study.

Setting

United States, 2015–2019.

Patient(s)

Women (n = 16,836,228) who delivered nonmalformed, singleton live births (24–44 weeks’ gestation).

Intervention(s)

Any infertility treatment, including assisted reproductive technology (ART) and prescribed fertility-enhancing medications.

Main Outcome Measure(s)

Small for gestational age birth, defined as sex-specific birth weight <10% for gestational age. Associations between SGA and infertility treatment were derived from Poisson regression with robust variance. Risk ratios (RR) and 95% confidence intervals (CI) were derived after adjusting for confounders. In a sensitivity analysis, we corrected for nondifferential exposure misclassification and unmeasured confounding biases.

Result(s)

Subsequently, 1.4% (n = 231,177) of pregnancies resulted from infertility treatments (0.8% ART and 0.6% fertility-enhancing medications). Of these, SGA births occurred in 9.4% (n = 21,771) and 11.9% (n = 1,755,925) of pregnancies conceived with infertility treatment and naturally conceived pregnancies, respectively (adjusted RR, 1.07; 95% CI, 1.06, 1.08). However, after correction for misclassification bias and unmeasured confounding, infertility treatment was associated with a 27% reduced risk of SGA (bias-corrected RR, 0.73; 95% CI, 0.53, 0.85). Similar trends were seen for analyses stratified by exposure to ART and fertility-enhancing medications, as well as for SGA <5th and <3rd percentiles.

Conclusion(s)

Exposure to infertility treatment is associated with a reduced risk of SGA births. These findings, which are contrary to some published reports, may reflect changes in the modern practice of infertility care, maternal lifestyle, and compliance with prenatal care within the infertile population. Until these findings are corroborated, the associations must be cautiously interpreted.