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Grand RoundsWeekly Evidence Brief

Obstetrics & Gynecology

Edition

30-Second Takeaway

  • Direct ultrasound markers of adenomyosis identify a high‑risk IVF phenotype with substantially lower live birth and higher pregnancy loss.
  • Natural‑cycle endometrial preparation yielded higher clinical pregnancy odds than HRT after intrauterine adhesion surgery in women ≤35.
  • When tumour stage is controlled, pregnancy‑associated melanoma does not worsen melanoma or overall survival.

Week ending May 16, 2026

Five recent studies with direct implications for obstetrics, IVF, and reproductive oncology counseling

Hospitals serving more Black births had higher TOLAC and VBAC rates, but Black‑White VBAC gap persisted

OBSTETRICS AND GYNECOLOGYMay 15, 2026

In 1,734,919 low‑risk deliveries with prior cesarean (2017–2019), hospitals in the top 5% of births to Black patients had higher adjusted odds of TOLAC (aOR 1.51) and VBAC (aOR 1.24). Overall, only 19.7% attempted TOLAC and 81.4% of attempts resulted in VBAC. Black patients remained less likely than White patients to achieve VBAC (aOR 0.88), though probabilities were higher at high Black‑serving hospitals. This retrospective, propensity‑matched analysis suggests institutional factors influence TOLAC/VBAC rates but cannot prove causation.

Baseline vaginal Lactobacillus modestly improves IVF outcome prediction when combined with clinical factors

FRONTIERS IN CELLULAR AND INFECTION MICROBIOLOGYMay 15, 2026

In 475 IVF couples, positive vaginal cultures occurred in 25.5% and positive semen cultures in 29%, with partner pathogen concordance <3%. Clinical pregnancy rates were similar between women with positive versus negative vaginal cultures (36% vs 39%, not significant). Machine‑learning models found maternal age the dominant predictor; microbial features, especially Lactobacillus presence, added modest predictive value. Baseline partner microbiology rarely overlapped, so treating presumed sexual transmission is unsupported by these data.

Natural‑cycle endometrial preparation associated with higher pregnancy rates after IUA separation surgery in women ≤35

FRONTIERS IN ENDOCRINOLOGYMay 14, 2026

Among women ≤35 with prior intrauterine adhesion separation, natural cycle (NC) FET had higher clinical pregnancy (47.5%) than HRT (30.9%) and higher biochemical pregnancy (50.5% vs 35.1%). Adjusted analyses showed NC versus HRT clinical pregnancy aOR 1.627 (95% CI 1.079–2.453) and biochemical aOR 1.532 (95% CI 1.020–2.301). Live birth and early miscarriage rates did not differ significantly between NC and HRT after adjustment. This retrospective cohort supports considering NC in this subgroup but is limited by nonrandomized design and potential residual confounding.

References

Numbered in order of appearance. Click any reference to view details.

Additional Reads

Optional additional studies from this edition.

Edition context

Clinical signal

  • Discuss adenomyosis subtype (direct MUSA markers) when counseling IVF patients about live birth and loss risk.
  • Consider natural cycle FET for patients ≤35 with prior IUA separation surgery; live birth differences were not significant.
  • In prenatal melanoma care, ensure complete staging before using pregnancy status to prognosticate.