Physical and mental development of children after fertilization and embryo transfer.

To evaluate the physical and mental development of children after fertilization (IVF) and frozen embryo transfer (FET). Between July 1995 and November 2003, 506 patients delivered 658 babies after IVF and ET treatment at our clinic (intracytoplasmic sperm injection (ICSI), 418; conventional IVF, (C-IVF) 125; FET, 115). A survey of the physical and mental developmental of the children was conducted by mailing questionnaires to parents. Comparisons were made between three treatment procedures, and development of singleton, twin and triplet delivery. The response rate was 73.4% (483/658) for 324 children born after ICSI, 78 born after C-IVF, and 81 born after FET. The height and weight of assisted reproductive technology (ART) children at birth were significantly lower than that of naturally conceived babies (ART children: natural delivery; 46.8 cm, 49.0 cm and 2524 g, 3040 g, respectively). However, there was no significant difference between the singletons alone and naturally conceived children irrespective of the ART method. In addition, mental development was the same between singletons and naturally conceived children. The ART group tended to delay body development such as 'holding their head up', 'sitting up', 'crawl' to moving growth in multiple births. The physical and mental development of twins or triplets was significantly more delayed than that of naturally conceived babies, but had improved to a similar extent of the singletons after the age of 6 months. (Reprod Med Biol 2004; : 63-67).