Three different cryopreservation methods and follow-up on babies

Abstract

OBJECTIVE: We investigated the physical development of babies born following three different cyropreservation methods; slow-cooling (straw), vitrification with cryoloop (loop), and vitrification with cryotop (top).DESIGN: Comparison among babies born following three different cyropreservation methods.MATERIALS AND METHODS: Between January, 1997 and November, 2007, 692 patients delivered babies after FET performed at our clinic, and we mailed questionnaires to them. Early cleaved embryos were frozen by straw, and blastocysts were frozen by loop or top. The control group consists of babies conceived from fresh embryo transfer. We evaluated delivery rates of single, twin, and triple births among three different crypreservation methods, and length of gestation period, and average birth weight, height, and girths of chest and head. Premature births and low birth-weight rates were also evaluated.RESULTS: Response rate of the questionnaire was 62.0%. The numbers of babies were 128 by straw, 43 by loop and 317 by top. Straw resulted in 86 singletons, 36 sets of twins (n=18) and 6 sets of triplets (n=2); loop resulted in 33 singletons, 10 sets of twins (n=5); top resulted in 257 singletons, 57 sets of twins (n=29), 3 sets of triplets (n=1). Comparing the results of babies from straw/loop/top/fresh embryo transfer, the length of gestation period, and average birth weight, height, and girths of chest and head had no significant difference. Premature births and low birth-weight rate were not significantly different. Death delivery rate was 1.2 %, and birth defect rate was 0.6 %.CONCLUSIONS: The method of cryopreservation does not adversely affect the growth or health of babies. Vitrification is a simple, easy, and quick method. It should be preferred to the slow-cooling method because of limited ice crystal formation and its convenience. It is anticipated that this method will be incorporated and undergo more development in other countries. OBJECTIVE: We investigated the physical development of babies born following three different cyropreservation methods; slow-cooling (straw), vitrification with cryoloop (loop), and vitrification with cryotop (top). DESIGN: Comparison among babies born following three different cyropreservation methods. MATERIALS AND METHODS: Between January, 1997 and November, 2007, 692 patients delivered babies after FET performed at our clinic, and we mailed questionnaires to them. Early cleaved embryos were frozen by straw, and blastocysts were frozen by loop or top. The control group consists of babies conceived from fresh embryo transfer. We evaluated delivery rates of single, twin, and triple births among three different crypreservation methods, and length of gestation period, and average birth weight, height, and girths of chest and head. Premature births and low birth-weight rates were also evaluated. RESULTS: Response rate of the questionnaire was 62.0%. The numbers of babies were 128 by straw, 43 by loop and 317 by top. Straw resulted in 86 singletons, 36 sets of twins (n=18) and 6 sets of triplets (n=2); loop resulted in 33 singletons, 10 sets of twins (n=5); top resulted in 257 singletons, 57 sets of twins (n=29), 3 sets of triplets (n=1). Comparing the results of babies from straw/loop/top/fresh embryo transfer, the length of gestation period, and average birth weight, height, and girths of chest and head had no significant difference. Premature births and low birth-weight rate were not significantly different. Death delivery rate was 1.2 %, and birth defect rate was 0.6 %. CONCLUSIONS: The method of cryopreservation does not adversely affect the growth or health of babies. Vitrification is a simple, easy, and quick method. It should be preferred to the slow-cooling method because of limited ice crystal formation and its convenience. It is anticipated that this method will be incorporated and undergo more development in other countries.