title: Does long in vitro culture promote large for gestational age babies?
abstract: OBJECTIVE
  Does the length of time during which embryos are cultured in vitro affect the birthweight of the infants?
  
  
  CONCLUSIONS
  The duration of the embryo culture period is a significant factor in determining the birthweight of the infants.
  
  
  BACKGROUND
  IVF children show adverse perinatal outcome when compared with the general population and increased incidence of preterm birth and low birthweight is commonly observed.
  
  
  METHODS
  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.
  
  
  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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  Small number of D5-6 infants and a lack of pregnancy-associated factors contributing to birthweight.
  
  
  CONCLUSIONS
  This study warrants larger studies to analyze the birthweight of the IVF children, particularly after blastocyst culture.
  
  
  BACKGROUND
  The study was funded by the Family Federation of Finland, Fertility Clinic Helsinki. No competing interests.
authors.affiliation: Family Federation of Finland, Fertility Clinic Helsinki, Helsinki, Finland.
authors.forename: S
authors.initials: S
authors.lastname: Mäkinen
authors.forename: V
authors.initials: V
authors.lastname: Söderström-Anttila
authors.forename: J
authors.initials: J
authors.lastname: Vainio
authors.forename: A-M
authors.initials: AM
authors.lastname: Suikkari
authors.forename: T
authors.initials: T
authors.lastname: Tuuri
mesh_terms: D000328:Adult; D001724:Birth Weight; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D004477:Ectogenesis; D046149:Embryo Culture Techniques; D005260:Female; D005307:Fertilization in Vitro / Q000009:adverse effects*; D005320:Fetal Macrosomia / Q000209:etiology*; D005387:Finland; D006801:Humans; D007231:Infant, Newborn; D007247:Infertility, Female / Q000503:physiopathology / Q000628:therapy; D007248:Infertility, Male / Q000503:physiopathology; D008297:Male; D011247:Pregnancy; D012189:Retrospective Studies; D020554:Sperm Injections, Intracytoplasmic / Q000009:adverse effects; D013997:Time Factors