title: Folic acid is positively associated with uteroplacental vascular resistance: the Generation R study.
abstract: OBJECTIVE
  Periconception folic acid supplementation may influence early placentation processes and thereby the occurrence of hypertensive pregnancy disorders. For this reason we examined the associations between periconception folic acid supplementation and uteroplacental vascular resistance, blood pressure, and the risks of gestational hypertension and preeclampsia, in 5993 pregnant women, participating in a population-based cohort study.
  
  
  RESULTS
  Folic acid supplementation was assessed by questionnaire. Mean pulsatility index (PI) and resistance index (RI) of the uterine (UtA) and umbilical arteries (UmA) were measured by Doppler ultrasound in mid- and late pregnancy. Systolic and diastolic blood pressures (SBP, DBP) were measured in early, mid- and late pregnancy. Compared to women who did not use folic acid, preconception folic acid users had a slightly lower UtA-RI in mid-pregnancy [β -0.02, 95% confidence interval (CI) -0.03, -0.01] and late pregnancy [β -0.02, 95% CI -0.03, -0.001], a lower UtA-PI in mid-pregnancy [β -0.06, 95% CI -0.1, -0.03] and late pregnancy [β -0.03, 95% CI -0.05, -0.01], as well as tendencies towards a lower UmA-PI in mid-pregnancy [β -0.02, 95% CI -0.04, -0.001] and late pregnancy [β -0.01, 95% CI -0.02, 0.01]. Additionally, these women had slightly higher SBP and DBP throughout pregnancy. Neither the patterns of blood-pressure change during pregnancy, nor the risk of gestational hypertension and preeclampsia differed between the folic acid categories.
  
  
  CONCLUSIONS
  Periconception folic acid supplementation is associated with lower uteroplacental vascular resistance and higher blood pressures during pregnancy. The effects are small and within physiologic ranges and seem not associated with the risk of hypertensive pregnancy disorders.
authors.affiliation: The Generation R Study Group, Erasmus MC Rotterdam, Rotterdam, the Netherlands. s.timmermans@erasmusmc.nl
authors.forename: S
authors.initials: S
authors.lastname: Timmermans
authors.forename: V W V
authors.initials: VW
authors.lastname: Jaddoe
authors.forename: L M
authors.initials: LM
authors.lastname: Silva
authors.forename: A
authors.initials: A
authors.lastname: Hofman
authors.forename: H
authors.initials: H
authors.lastname: Raat
authors.forename: R P M
authors.initials: RP
authors.lastname: Steegers-Theunissen
authors.forename: E A P
authors.initials: EA
authors.lastname: Steegers
mesh_terms: D000293:Adolescent; D000328:Adult; D001794:Blood Pressure / Q000187:drug effects; D015331:Cohort Studies; D019587:Dietary Supplements; D005260:Female; D005492:Folic Acid / Q000494:pharmacology*; D005865:Gestational Age; D006801:Humans; D046110:Hypertension, Pregnancy-Induced / Q000453:epidemiology / Q000503:physiopathology; D021041:Placental Circulation / Q000187:drug effects*; D011225:Pre-Eclampsia / Q000453:epidemiology; D011247:Pregnancy; D011264:Pregnancy Trimesters; D012959:Socioeconomic Factors; D014463:Ultrasonography; D014469:Umbilical Arteries / Q000000981:diagnostic imaging / Q000503:physiopathology; D014655:Vascular Resistance / Q000187:drug effects*; D014815:Vitamins / Q000494:pharmacology*; D055815:Young Adult
chemical_list: D014815:Vitamins; D005492:Folic Acid