title: Blood pressure dynamics during pregnancy and spontaneous preterm birth.
abstract: OBJECTIVE
  The objective of the study was to examine whether blood pressure in early pregnancy and its rise in the second half of gestation are associated with spontaneous preterm birth in healthy, normotensive, nulliparous women.
  
  
  METHODS
  We included 5167 women with singleton gestation who participated in the World Health Organization Calcium Supplementation for the Prevention of Preeclampsia Trial. Systolic, diastolic, and mean arterial blood pressure and pulse pressure at baseline (12-19 weeks of gestation) and at the midthird trimester (30-34 weeks) were calculated. Rise in blood pressure was the difference between the midthird trimester and baseline. Preterm birth was defined as early preterm (less than 34 completed weeks) and late preterm birth (34-36 weeks).
  
  
  RESULTS
  Women experiencing early or late preterm birth had over 10 mm Hg and 3 mm Hg higher rise, respectively, in systolic, diastolic, and mean arterial blood pressure than women delivering at term. A rise in systolic pressure over 30 mm Hg or diastolic pressure over 15 mm Hg was associated with a statistically significant 2- to 3-fold increase in risk of spontaneous preterm birth.
  
  
  CONCLUSIONS
  An excessive rise in either systolic or diastolic blood pressures from early pregnancy to the midthird trimester is associated with spontaneous preterm birth in a dose-response pattern.
authors: Division of Epidemiology, Statistics and Prevention Research, National Institute of Child Health and Human Development, National Institutes of Health, Department of Health and Human Services, Bethesda, MD, USA.
authors: Jun
authors: J
authors: Zhang
authors: Jose
authors: J
authors: Villar
authors: Wenyu
authors: W
authors: Sun
authors: Mario
authors: M
authors: Merialdi
authors: Hany
authors: H
authors: Abdel-Aleem
authors: Matthews
authors: M
authors: Mathai
authors: Mohamed
authors: M
authors: Ali
authors: Kai F
authors: KF
authors: Yu
authors: Nelly
authors: N
authors: Zavaleta
authors: Manorama
authors: M
authors: Purwar
authors: Thi Nhu Ngoc
authors: TN
authors: Nguyen
authors: Liana
authors: L
authors: Campodonico
authors: Sihem
authors: S
authors: Landoulsi
authors: Marshall
authors: M
authors: Lindheimer
authors: Guillermo
authors: G
authors: Carroli
mesh_terms: D000328:Adult; D001794:Blood Pressure; D015331:Cohort Studies; D005260:Female; D006801:Humans; D011225:Pre-Eclampsia / Q000503:physiopathology; D011247:Pregnancy; D047928:Premature Birth / Q000208:ethnology / Q000209:etiology*; D012307:Risk Factors
references: Prostaglandins. 1981 Feb;21(2):277-86
references: 7012935
references: Clin Sci (Lond). 2005 Aug;109(2):209-15
references: 15859943
references: Clin Sci (Lond). 2004 Apr;106(4):377-82
references: 14636154
references: Hum Pathol. 1989 May;20(5):441-4
references: 2707795
references: Hypertens Pregnancy. 2005;24(2):137-45
references: 16036398
references: Am J Obstet Gynecol. 2006 Mar;194(3):639-49
references: 16522392
references: Eur J Obstet Gynecol Reprod Biol. 1993 May;49(3):161-8
references: 8405630
references: Am J Perinatol. 1997 Jan;14(1):17-23
references: 9259891
references: Curr Pharm Des. 2003;9(5):359-80
references: 12570814
references: Am J Obstet Gynecol. 2006 Apr;194(4):921-31
references: 16580277
references: Obstet Gynecol. 2002 Nov;100(5 Pt 1):1020-37
references: 12423870
references: Am J Obstet Gynecol. 1964 Oct 15;90:505-10
references: 14217652
references: Int J Gynaecol Obstet. 2004 Jun;85 Suppl 1:S28-41
references: 15147852
references: J Soc Gynecol Investig. 1998 Mar-Apr;5(2):68-71
references: 9509383
references: Am J Obstet Gynecol. 2003 Oct;189(4):1063-9
references: 14586356
references: Obstet Gynecol. 2004 Jul;104(1):78-87
references: 15229004