Better outcomes seen with delay in next frozen embryo transfer after pregnancy loss

Key takeaways:

• Women with shorter vs. longer interpregnancy intervals had worse odds of clinical pregnancy loss, live birth and healthy live birth.
• Women with longer vs. shorter intervals had lower total pregnancy loss risk.

Delaying frozen embryo transfer for at least 6 months after clinical pregnancy loss was linked to better pregnancy outcomes vs. shorter interpregnancy intervals, according to study findings published in JAMA Network Open.

“Women who conceive by IVF treatment generally have an increased risk of adverse pregnancy outcomes compared with those who conceive naturally. Moreover, women who have experienced a clinical pregnancy loss during IVF treatment are more prone to psychological distress,” Ze Wang, MD, from the Center for Reproductive Medicine at Shandong University, China, and colleagues wrote. “Nevertheless, few studies have addressed the optimal interpregnancy interval after a preceding clinical pregnancy loss in IVF populations.”

Wang and colleagues conducted a retrospective cohort study with data from 2,433 women (mean age, 31.8 years) from the Center for Reproductive Medicine of Shandong University in China. Between July 2017 and June 2022, all women underwent frozen-thawed blastocyst transfer within 1 year after a clinical pregnancy loss during IVF.

The primary outcomes were live birth, conception, clinical pregnancy, pregnancy loss, preterm birth, small or large for gestational age and low birth weight.

Overall, 13.9% of women had an interpregnancy interval of less than 3 months (median length, 77 days), 55.4% had an interval of 3 to 6 months (median length, 128 days) and 30.7% had an interval of 6 to 12 months (median length, 234 days).

Researchers observed lower odds of clinical pregnancy among interpregnancy intervals of less than 3 months (adjusted OR = 0.7; 95% CI, 0.53-0.92) or 3 to 6 months (aOR = 0.79; 95% CI, 0.65-0.95) compared with 6 to 12 months. In addition, shorter interpregnancy intervals were associated with lower odds of live birth (< 3 months, aOR = 0.64; 95% CI, 0.48-0.85; 3 to 6 months, aOR = 0.74; 95% CI, 0.61-0.9) and healthy live birth (< 3 months, aOR = 0.63; 95% CI, 0.46-0.87; 3 to 6 months, aOR = 0.79; 95% CI, 0.64-0.98) compared with 6 to 12 months.

Researchers also noted a higher risk for total pregnancy loss among women with interpregnancy intervals of less than 3 months (aOR = 1.87; 95% CI, 1.31-2.67) or 3 to 6 months (aOR = 1.29; 95% CI, 1-1.66) compared with women with interpregnancy intervals of 6 to 12 months.

According to the researchers, these findings suggest that delaying frozen embryo transfer for at least 6 months after a clinical pregnancy loss was associated with better pregnancy outcomes.

“Further prospective studies are needed to confirm our findings,” the researchers wrote.