High-altitude ancestry protects against IUGR and reductions in birth weight associated with high altitude and preeclampsia
Fecha
2005-02-22Autor
Julian, Colleen Glyde
Vargas, Enrique
MacCannell, Wendy
Armaza, Fernando
Moore, Lorna G
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Background.
Observations consistently demonstrate diminished birth weight [BW] with ascending altitude;
however population comparisons reveal the extent of BW
reduction depends, in part, upon high-altitude ancestry.
Objective(s): To examine the influence of variable HA ancestry [Andean, European and Mestizo (admixed)] on
BW, IUGR and hypertensive complications across a range
of altitudes. Methods: Maternal and infant characteristics
were collected from medical records of 3538 consecutive
deliveries to women having 2 prenatal visits at public
or private hospitals in Santa Cruz [300m, LA],
Cochabamba [2500m, MA] and La Paz or Orurro [3600-
3800m, HA], Bolivia. Population ancestry was determined
using parental surnames. IUGR was defined as birth
weights 10th percentile for gestational age and sex using sea-level criteria. Hypertension during pregnancy
was defined as two or more BP readings at least six hours
apart 140/90 mmHg, or a 30/15 mmHg rise above
values recorded at the first prenatal visit in a woman
whose BP was 140/90 mmHg before week 20 or postpartum. Severe preeclampsia [PE] was defined BP
160/110 mmHg in late pregnancy and all other cases of
PE, gestational hypertension [GH] or PE/GH were considered mild. Results: BW declined with ascending altitude [HA: 3365 18; MA: 3306 16 and LA: 3101 12;
p 0.0001], however gestational age was equivalent [p
NS]. BW diminished 70g, 56g and 39g per 1000m increase
in elevation for Europeans, Mestizoes and Andeans, respectively. IUGR prevalence increased with altitude
among Mestizo and European babies; Andeans were unaffected. Likewise, at HA, Andean BW was unaffected by
mild or severe PE, whereas severe PE diminished Mestizo and European birth weight [ 346g, 1608g, respectively]; mild PE tended to increase European BW at HA
[ 301.4g]. Conclusions: High-altitude ancestry protects
infants from IUGR and reductions in birth weight associated with high-altitude and hypertensive complications
during pregnancy.