Time‐Lapse Culture Improves Development and Pregnancy Outcomes of Sibling Normally Fertilized Oocytes: A Prospective Multicenter Study

Purpose To evaluate whether time‐lapse monitoring improves embryological outcomes and clinical pregnancy rates compared to conventional culture in a sibling‐oocyte study. Methods This multicenter‐study involved 205 first‐time retrieval cycles ( n = 3244 mature oocytes). Sibling‐oocytes from patients with ≥ 4 oocytes were randomized into conventional and time‐lapse groups. The primary outcome was the good‐quality blastocyst rate. Key secondary outcomes included Day‐2 Good Quality Embryo (GQE) rates and clinical pregnancy rates for both fresh and frozen–thawed embryo transfers (FET). Results The time‐lapse group exhibited a significantly higher GQE rate on Day 2 (42.1% vs. 35.3%, p < 0.01) and a higher good‐quality blastocyst rate (44.1% vs. 38.1%, p < 0.01) compared to the conventional group. While clinical pregnancy rates showed a higher trend in the time‐lapse group for both fresh ET (44.4% vs. 15.8%) and FET (45.3% vs. 36.7%), these differences did not reach statistical significance. Time‐lapse monitoring successfully identified embryos with early pronuclear disappearance as early as 14 h post‐insemination. Morphokinetic analysis revealed that abnormal cleavage patterns were associated with significantly lower blastocyst development potential compared to normal cleavage ( p < 0.01). Conclusion Time‐lapse culture provides a stable environment that enhances embryo quality. While clinical pregnancy rates showed a positive trend, further large‐scale studies are needed to confirm the impact on live birth rates.