RT Journal Article SR Electronic T1 Influence of genetic variants for birth weight on fetal growth and placental haemodynamics JF Archives of Disease in Childhood - Fetal and Neonatal Edition JO Arch Dis Child Fetal Neonatal Ed FD BMJ Publishing Group Ltd and Royal College of Paediatrics and Child Health SP 393 OP 398 DO 10.1136/archdischild-2019-317044 VO 105 IS 4 A1 Vermeulen, Marijn J A1 Gaillard, Romy A1 Miliku, Kozeta A1 Reiss, Irwin A1 Steegers, Eric A P A1 Jaddoe, Vincent A1 Felix, Janine YR 2020 UL http://fn.bmj.com/content/105/4/393.abstract AB Objective To determine the combined effect of 60 genetic variants (single nucleotide polymorphisms, SNPs), previously identified as being associated with birth weight, on fetal growth and placental haemodynamics throughout pregnancy.Design Prospective birth cohort (Generation R Study).Setting General multiethnic population.Participants 5374 singleton liveborn children with genome-wide association arrays and fetal growth data.Methods Longitudinal and cross-sectional analyses of a genetic score of the total number of birth weight–increasing alleles across the 59 available SNPs and repeated fetal growth and haemodynamic measures.Main outcome measures SD scores (SDS) of fetal weight, (femur) length, head circumference, umbilical artery pulsatility index, uterine artery mean resistance index and placental weight, in different periods of pregnancy until birth.Results In longitudinal analyses, the effect of the genetic score on the fetal growth measures increased throughout pregnancy (p<0.001). At 20 weeks of gestation, the genetic score was not associated with any of the fetal growth measures, whereas at 30 weeks it was associated with all. The strongest effects were observed at birth: per SD increase in genetic score, birth weight increased by 0.15 SDS (95% confidence interval: 0.13 to 0.18), birth length by 0.12 SDS (0.08 to 0.19) and head circumference by 0.08 SDS (0.05 to 0.12). The genetic score was not associated with placental haemodynamics, but was associated with a 14 g (10 to 18) increase in placental weight per SDS increase in genetic score.Conclusions Our results suggest that genetic variants related to birth weight exert their combined effect on fetal growth from second half of pregnancy onwards and have no effect on placental haemodynamics.