STUDY QUESTION: Does the length of time during which embryos are cultured in vitro affect the birthweight of the infants? SUMMARY ANSWER: The duration of the embryo culture period is a significant factor in determining the birthweight of the infants. WHAT IS ALREADY KNOWN: IVF children show adverse perinatal outcome when compared with the general population and increased incidence of preterm birth and low birthweight is commonly observed. STUDY DESIGN, SIZE, DURATION: A retrospective cross-sectional cohort study including 1079 infants born after treatment at the Family Federation of Finland Fertility Clinic in Helsinki, between 2000 and 2010. PARTICIPANTS, SETTING, METHODS: All singleton IVF children were included. The gestation- and gender-adjusted birthweights of the babies were analyzed according to mother's age, BMI, and parity, type of treatment (IVF or ICSI), main cause of infertility and embryo culture period. Two outcomes were investigated: the birthweight and the proportion of small and large for gestational age (SGA and LGA) infants. Multiple linear regression analysis was performed to show the significance of each individual factor on determining the birthweight of the babies born. MAIN RESULTS AND THE ROLE OF CHANCE: In the study group as a whole, the distribution of the SGA and LGA babies showed no deviation from the growth charts of the general population. However, when the birthweight of the children was analyzed according to the length of embryo culture from Day 2 to Days 5-6, an increase in the proportion of LGA babies was found (D2 9.4%, D3 11.5%, D5-6 18.8%; D2 n = 871, D3 n = 139, D5-6 n = 69). Multiple linear regression analysis showed that BMI (P < 0.001) and parity (P < 0.001) of the mother, as well as the embryo culture period (P = 0.007) had a significant effect on the birthweight. The value of the adjusted R(2) was 0.437. LIMITATIONS, REASONS FOR CAUTION: Small number of D5-6 infants and a lack of pregnancy-associated factors contributing to birthweight. WIDER IMPLICATIONS OF THE FINDING: This study warrants larger studies to analyze the birthweight of the IVF children, particularly after blastocyst culture. STUDY FUNDING/COMPETING INTEREST: The study was funded by the Family Federation of Finland, Fertility Clinic Helsinki. No competing interests.
STUDY QUESTION: Does the length of time during which embryos are cultured in vitro affect the birthweight of the infants? SUMMARY ANSWER: The duration of the embryo culture period is a significant factor in determining the birthweight of the infants. WHAT IS ALREADY KNOWN: IVFchildren show adverse perinatal outcome when compared with the general population and increased incidence of preterm birth and low birthweight is commonly observed. STUDY DESIGN, SIZE, DURATION: A retrospective cross-sectional cohort study including 1079 infants born after treatment at the Family Federation of Finland Fertility Clinic in Helsinki, between 2000 and 2010. PARTICIPANTS, SETTING, METHODS: All singleton IVFchildren were included. The gestation- and gender-adjusted birthweights of the babies were analyzed according to mother's age, BMI, and parity, type of treatment (IVF or ICSI), main cause of infertility and embryo culture period. Two outcomes were investigated: the birthweight and the proportion of small and large for gestational age (SGA and LGA) infants. Multiple linear regression analysis was performed to show the significance of each individual factor on determining the birthweight of the babies born. MAIN RESULTS AND THE ROLE OF CHANCE: In the study group as a whole, the distribution of the SGA and LGA babies showed no deviation from the growth charts of the general population. However, when the birthweight of the children was analyzed according to the length of embryo culture from Day 2 to Days 5-6, an increase in the proportion of LGA babies was found (D2 9.4%, D3 11.5%, D5-6 18.8%; D2 n = 871, D3 n = 139, D5-6 n = 69). Multiple linear regression analysis showed that BMI (P < 0.001) and parity (P < 0.001) of the mother, as well as the embryo culture period (P = 0.007) had a significant effect on the birthweight. The value of the adjusted R(2) was 0.437. LIMITATIONS, REASONS FOR CAUTION: Small number of D5-6 infants and a lack of pregnancy-associated factors contributing to birthweight. WIDER IMPLICATIONS OF THE FINDING: This study warrants larger studies to analyze the birthweight of the IVFchildren, particularly after blastocyst culture. STUDY FUNDING/COMPETING INTEREST: The study was funded by the Family Federation of Finland, Fertility Clinic Helsinki. No competing interests.
Authors: Barbara Luke; Morton B Brown; Ethan Wantman; Judy E Stern; James P Toner; Charles C Coddington Journal: J Assist Reprod Genet Date: 2016-12-01 Impact factor: 3.412