Low estrogen excretion during pregnancy at high altitude

Sobrevilla, Luis A.; Romero, I.; Kruger, Francisco; Whittembury, J

doi:10.1016/0002-9378(68)90510-3

Cited by 33 publications

(14 citation statements)

References 17 publications

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“…Oestrogen administration improves arterial endothelium-dependent vasodilation 27 and in postmenopausal women in vivo, oestrogens enhance NO derivatives and improve endothelium-dependent vasodilation 28 -32 . In pregnancy at high altitude, maternal venous oestrogen levels and urinary oestrogen secretion have been shown to be lower than those of mothers at sea level 33,34 . However, oestrogen upregulation of NO production appears to reach a plateau, above which increase in oestrogen levels does not increase further NO production 28,29 .…”

Section: Discussionmentioning

confidence: 96%

Flow-mediated dilatation of the brachial artery in pregnancy at high altitude

Kametas¹

2002

BJOG: An International Journal of Obstetrics and Gynaecology

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Objective Pregnancy at high altitude has been associated with increased prevalence of pre-eclampsia and reduced maternal oestrogen levels, factors that have been associated with endothelial dysfunction. The aim of this study was to examine the effect of high altitude (4370 m above sea level) on endothelial function during pregnancy as assessed by a non-invasive method. Design Cross-sectional study.Setting Two maternity units providing routine antenatal care: one at high altitude (District General Hospital -IPSS in Cerro de Pasco, Peru) and one at sea level (Instituto Materno-Perinatal in Lima, Peru). Population Sixty pregnant women at 6 -42 weeks of gestation resident at high altitude (Cerro de Pasco, Peru, 4370 m above sea level) and 54 at sea level (Lima, Peru). Comparisons were performed also in 11 and 14 non-pregnant women at each altitude, respectively. Methods Endothelial function was assessed by flow-mediated dilatation of the brachial artery using highresolution ultrasound. Main outcome measures Differences in flow mediated dilatation of the brachial artery in two groups of pregnant women, one at high altitude and one at sea level. Results Both at high altitude and sea level flow-mediated dilatation of the brachial artery increased in the first two trimesters to levels 32% higher than non-pregnant controls. However, in the third trimester, flowmediated dilatation of the brachial artery was lower than non-pregnant levels. Resting vessel size increased during pregnancy by 15% compared with non-pregnant controls at term, with no difference between the two populations at high and low altitude. Pregnancy at high altitude, compared with sea level, was associated with 59% lower baseline blood flow and 76% higher reactive hyperaemia. Similarly, non-pregnant controls at high altitude compared with sea level demonstrated similar flow-mediated dilatation of the brachial artery and 40% lower resting blood flow of the brachial artery. However, the difference in reactive hyperaemia did not reach statistical significance. Conclusion These data suggest that, during pregnancy at high altitude, endothelial function, as assessed by flow-mediated dilatation of the brachial artery, is not impaired.

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Section: Discussionmentioning

confidence: 96%

Flow-mediated dilatation of the brachial artery in pregnancy at high altitude

Kametas¹

2002

BJOG: An International Journal of Obstetrics and Gynaecology

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“…The hypoxia seems a sensible hypothesis for high altitude (Ͼ1,500 m) (Yip et al, 1988). Other studies have found anatomic differences in high-altitude placentas (Kruger and AriasStella, 1970), low estrogen excretion during pregnancy at high altitude (Sobrevilla et al, 1968) and increase in amniotic fluid index (Yancey and Richards, 1994), but the effect of these factors in birth weight is controversial. The above-mentioned facts and hypotheses suggest that altitude influences birth weight but not gestational age.…”

Section: Discussionmentioning

confidence: 98%

Risk factors for low birth weight: Results from a case-control study in southern Spain

Delgado-Rodrı́guez

Pérez-Iglesias

Gómez-Olmedo

et al. 1998

Am. J. Phys. Anthropol.

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The main objective of this study is to examine the effect of several variables, including altitude of maternal residence, on delivering a low birth weight (LBW) newborn. A case-control study was done. Two hundred forty cases (single newborn weighing less than 2,500 g) and 374 controls (single newborn weighing more than 2,499 g) were included. Information was gathered from the clinical chart of delivering women, through a personal interview and the Spanish Census Bureau (for altitude). Predictors of LBW were assessed through stepwise logistic regression analysis. Several well-known LBW risk factors were identified: hypertension, weight gain during pregnancy, body size (mainly maternal prepregnancy weight), low social class, primiparity, and several conditions (spontaneous delivery, abruptio placentae). Altitude was an independent predictor of LBW at term (more than 37 weeks of gestational age) but not for preterm LBW. Nevertheless, a relationship between altitude and birth weight was not found in controls, although a moderate decreasing gradient with altitude was observed. The limitations of these findings are discussed.

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“…The present study confirmed that smoking has little effect upon placental weight. This is of some importance since it has been established that at high altitudes there is a decrease in excretion of oestrogen in the urine during pregnancy and an increase in placental weight (Sobrevilla et al, 1968).…”

Section: D~scussionmentioning

confidence: 99%

An Evaluation of the Effects of Smoking on Maternal Oestriol Excretion During Pregnancy and on Fetal Outcome

Targett

Gunesee

McBride

et al. 1973

BJOG

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Summary In 1000 consecutive patients with singleton pregnancies 38.7 per cent were smokers and 13.7 per cent had subnormal oestriol excretion. There was a significant correlation between low oestriol excretion and both intrauterine fetal growth retardation and perinatal mortality (P<0.001). Smoking had a significant correlation with intrauterine growth retardation (P<0.001), but not with perinatal mortality (P<0.05). The incidence of low oestriol excretion in smokers (15.5 per cent) was not significantly different from that in non‐smokers (12.6 per cent) (P<0.25). Further study is required to evaluate the effects of heavy smoking on feto‐placental function. Hypoxia is probably not the important influence causing fetal growth retardation in smokers.

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Low estrogen excretion during pregnancy at high altitude

Cited by 33 publications

References 17 publications

Flow-mediated dilatation of the brachial artery in pregnancy at high altitude

Flow-mediated dilatation of the brachial artery in pregnancy at high altitude

Risk factors for low birth weight: Results from a case-control study in southern Spain

An Evaluation of the Effects of Smoking on Maternal Oestriol Excretion During Pregnancy and on Fetal Outcome

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