[Normal sperm morphology and the outcomes of routine in vitro fertilization]

To explore the application value of morphology assessment of sperm from fresh semen in routine in vitro fertilization (IVF).

We analyzed the morphology of the sperm from fresh or optimized semen samples and, based on the sperm morphology of the raw semen, allocated 908 IVF cycles due to the pure tubal factor to different groups: morphologically normal sperm (MNS) ≤ 4%, > 4% - ≤ 15%, and > 15% in Trial 1 and MNS ≤ 1%, > 1% - ≤ 2%, > 2% - ≤ 3%, and > 3%-- ≤ 4% in Trial 2. We compared the rates of fertilization, cleavage, high-quality embryo, -blastocyst formation, and pregnancy among different groups.

The total fertilization rate was significantly lower in the MNS ≤ 4% than in the MNS > 4% - ≤ 15% and >15% groups (74.40% vs 78.61% and 80.03%, P < 0.01). Compared with the MNS ≤ 1%, > 1% - ≤ 2%, and > 2% - ≤ 3% groups, the MNS > 3% - ≤ 4% group showed remarkably increased rates of 2PN normal fertilization (77.23%, 78.97% and 78.99% vs 85.47%, P < 0.01), cleavage (95.71%, 96.01% and 97.27% vs 98.73%, P < 0.05), and blastocyst formation (53.85%, 49.01% and 49.55% vs 63.41%, P < 0.01). No statistically significant differences were observed in the rates of clinical pregnancy, implantation, early abortion, live birth, or malformation at birth among different groups (P > 0.05).

MNS ≤ 4% affected the total rate of fertilization while MNS ≤ 3% reduced the rate of normal fertilization in IVF. However, even MNS ≤ 1% did not result in fertilization disorder or failure. Therefore, teratozoospermia alone was not an indicator of ICSI and sperm mor- phology assessment had no obvious value for predicting the rates of embryo quality, clinical pregnancy, and live birth in IVF.