title: Greater uterine artery blood flow during pregnancy in multigenerational (Andean) than shorter-term (European) high-altitude residents.
abstract: Multigenerational (Andean) compared with shorter-term (European) high-altitude residents exhibit less hypoxia-associated reductions in birth weight. Because differences in arterial O(2) content are not responsible, we asked whether greater pregnancy-associated increases in uterine artery (UA) blood flow and O(2) delivery were involved. Serial studies were conducted in 42 Andean and 26 European residents of La Paz, Bolivia (3600 m) at weeks 20, 30, 36 of pregnancy and 4 mo postpartum using Doppler ultrasound. There were no differences postpartum but Andean vs. European women had greater UA diameter (0.65 +/- 0.01 vs. 0.56 +/- 0.01 cm), cross-sectional area (33.1 +/- 0.97 vs. 24.7 +/- 1.18 mm(2)), and blood flow at week 36 (743 +/- 87 vs. 474 +/- 36 ml/min) (all P < 0.05) and thus 1.6-fold greater uteroplacental O(2) delivery near term (126.82 +/- 18.47 vs. 80.33 +/- 8.69 ml O(2).ml blood(-1).min(-1), P < 0.05). Andeans had greater common iliac (CI) flow and lower external iliac relative to CI flow (0.52 +/- 0.11 vs. 0.95 +/- 0.14, P < 0.05) than Europeans at week 36. After adjusting for gestational age, maternal height, and parity, Andean babies weighed 209 g more than the Europeans. Greater UA cross-sectional area at week 30 related positively to birth weight in Andeans (r = +0.39) but negatively in Europeans (r = -0.37) (both P < 0.01). We concluded that a greater pregnancy-associated increase in UA diameter raised UA blood flow and uteroplacental O(2) delivery in the Andeans and contributed to their ability to maintain normal fetal growth under conditions of high-altitude hypoxia. These data implicate the involvement of genetic factors in protecting multigenerational populations from hypoxia-associated reductions in fetal growth, but future studies are required for confirmation and identification of the specific genes involved.
authors.affiliation: Altitude Research Center, University of Colorado at Denver and Health Sciences Center, 4200 East Ninth Avenue, Denver, CO 80262, USA. Megan.Wilson@UCHSC.edu
authors.forename: Megan J
authors.initials: MJ
authors.lastname: Wilson
authors.forename: Miriam
authors.initials: M
authors.lastname: Lopez
authors.forename: Marco
authors.initials: M
authors.lastname: Vargas
authors.forename: Colleen
authors.initials: C
authors.lastname: Julian
authors.forename: Wilma
authors.initials: W
authors.lastname: Tellez
authors.forename: Armando
authors.initials: A
authors.lastname: Rodriguez
authors.forename: Abigail
authors.initials: A
authors.lastname: Bigham
authors.forename: J Fernando
authors.initials: JF
authors.lastname: Armaza
authors.forename: Susan
authors.initials: S
authors.lastname: Niermeyer
authors.forename: Mark
authors.initials: M
authors.lastname: Shriver
authors.forename: Enrique
authors.initials: E
authors.lastname: Vargas
authors.forename: Lorna G
authors.initials: LG
authors.lastname: Moore
mesh_terms: D000328:Adult; D000531:Altitude; D001699:Biometry; D001724:Birth Weight / Q000502:physiology; D001810:Blood Volume / Q000502:physiology; D001838:Bolivia; D036861:Delivery, Obstetric; D005060:Europe / Q000208:ethnology; D005260:Female; D047109:Fetal Development / Q000502:physiology; D005311:Fetal Hypoxia / Q000503:physiopathology; D006801:Humans; D007199:Indians, South American; D007231:Infant, Newborn; D035002:Lower Extremity / Q000098:blood supply; D011247:Pregnancy / Q000235:genetics* / Q000502:physiology*; D012039:Regional Blood Flow / Q000235:genetics / Q000502:physiology; D014599:Uterus / Q000098:blood supply*; D014655:Vascular Resistance / Q000502:physiology