Vilma Tapia

Maternal hemoglobin level and fetal outcome at low and high altitudes

Both, low (<7 g/dl) and high (>14.5 g/dl), maternal hemoglobin (Hb) levels have been related to poor fetal outcome. Most studies have been done at low altitude (LA). Here, we have sought to determine whether this relationship exists at both high and low altitude, and also whether there is an adverse effect of high altitude (HA) on fetal outcome independent of level of maternal hemoglobin. The study is based on a retrospective multicenter analysis of 35,449 pregnancies at LA and six other cities above 3000 meters. In analyses of all women at both LA and HA, those with Hb <9 g/dl had odds ratios (ORs) and 95% confidence intervals (CI) of 4.4 (CI: 2.8-6.7), 2.5 (CI: 1.9-3.2), and 1.4 (CI: 1.1-1.9) for stillbirths, preterm, and small for gestational age (SGA) births, respectively, compared with women with 11-12.9 g/dl of Hb, after adjustment for confounders. These risks by hemoglobin level differed little between women at LA and HA, suggesting that no correction of the definition of anemia is necessary for women at HA. Women living at high altitude with hemoglobin >15.5 g/dl had higher risks for stillbirths (OR: 1.3; CI: 1.05-1.3), preterm (OR: 1.5; CI 1.3-1.8), and SGA births (OR: 2.1, CI 1.8-2.3). There was also a significant adverse effect of living at HA, independent of hemoglobin level for all three outcomes (OR: 3.9, 1.7, and 2.3; CI: 2.8-5.2, 1.5-1.9, and 2.1-2.5) for stillbirths, preterms, and SGA respectively, after adjusting for hemoglobin level. Both, high and low maternal hemoglobin levels were related to poor pregnancy outcome, with similar effect of low hemoglobin in both LA and HA. Our data suggest, that maternal hemoglobin above 11 g/dl but below 13 g/dl is the area of minimal risk of poor adverse outcomes. Living at HA had an adverse effect independent of hemoglobin level.

Birth weight at high altitudes in Peru

Objective: To determine whether birth weights are lower at high altitudes, and whether gestational age at birth and a populations length of residence mitigate the effect of high altitude.

High serum testosterone levels are associated with excessive erythrocytosis of chronic mountain sickness in men

Chronic mountain sickness (CMS) is characterized by excessive erythrocytosis (EE) secondary to hypoventilation. Erythropoietin (Epo) and testosterone regulate erythrocyte production. Low thyroid hormone levels are also associated to hypoventilation. Hence, these hormones can play a role in etiopathogeny of EE. The purpose of this study was to elucidate the effect of sexual and thyroid hormones and Epo in residents from Lima (150 m) and Cerro de Pasco (4,340 m), Peru, and the response to human chorionic gonadotrophin stimulation (hCG). Three groups, one at low altitude and two at high altitude [1 with hemoglobin values >16-21 g/dl and the second with Hb >or=21 g/dl (EE)], were studied. hCG was administered intramuscularly in a single dose (1,000 IU), and blood samples were obtained at 0, 6, 12, 24, 48, and 72 h after injection. High-altitude natives present similar levels of gonadotropins and thyroid hormones but lower dehydroepiandrosterone sulphate (DHEAS) levels (P < 0.01) and greater Epo (P < 0.01), 17alpha-hydroxyprogesterone (P < 0.01), and testosterone levels (P < 0.01) than those at 150 m. Serum testosterone levels (524.13 +/- 55.91 microg/dl vs. 328.14 +/- 53.23 ng/dl, means +/- SE; P < 0.05) and testosterone/DHEAS ratios are higher (7.98 +/- 1.1 vs. 3.65 +/- 1.1; P < 0.01) and DHEAS levels lower in the EE group (83.85 +/- 14.60 microg/dl vs. 148.95 +/- 19.11 ug/dl; P < 0.05), whereas Epo was not further affected. Testosterone levels were highest and DHEAS levels lowest in the EE group at all times after hCG stimulation. In conclusion, high androgen activity could be involved in the etiopathogeny of CMS. This evidence provides an opportunity to develop new therapeutic strategies.

Stillbirth rates in Peruvian populations at high altitude

To compare the stillbirth rates in 4 cities at different altitudes in Peru.

Maternal hemoglobin concentration and adverse pregnancy outcomes at low and moderate altitudes in Peru

Objective: To identify associations of maternal hemoglobin (Hb) with perinatal outcomes at low and moderate altitudes in Peru. Methods: Study of records with sequential information using perinatal database system. The study included 295 651 pregnant women with their products. Using multiple logistic regression analysis, we estimated the probability of stillbirths, preterm and small for gestational age (SGA) births associated with maternal Hb levels at low (0–1999 m) and moderate altitudes (2000–2999 m). Results: Maternal Hb decreased as pregnancy progressed from first to third trimester at both altitudes. Hb was higher at moderate than at low altitude (p < 0.001). Risks for stillbirths increased with low maternal Hb (odds ratio [OR]: 1.39 for Hb 9–9.9; OR: 1.84 for Hb 8–8.9; OR: 3.25 for Hb 7–7.9; and OR: 7.8 for Hb <7 g/dl); with Hb higher than 14.5 g/dl (OR: 1.31) and with altitudes ≥2000 m (OR: 1.2). High preterm rates were also observed with low Hbs (OR: 1.16 for Hb 9–9.9; OR: 1.64 for Hb 8–8.9; OR: 2.25 for Hb 7–7.9; and OR:2.87 for Hb<7 g/dl) and with Hb higher than 14.5 g/dl (OR: 1.14). High SGA rates were observed in neonates with maternal Hb of 7–7.9 (OR: 1.35) and <7 g/dl (OR:1.57), and higher than 14.5 g/dl (OR: 1.33), and with moderate altitudes (OR: 1.12). The cut-off points for lower risks of stillbirth and preterm births was 10 g/dl, and for SGA 9 g/dl of hemoglobin. Conclusion: Low and high maternal Hb levels and moderate altitude were independent risk factors for adverse perinatal outcomes.

Birth weight charts for gestational age in 63 620 healthy infants born in Peruvian public hospitals at low and at high altitude

Aim: To construct distribution curves for birth weight, length and head circumference using a large sample of infants born at low (150 m) and high (3000–4400 m) altitude.

Maternal and Perinatal Outcomes in Second Hemoglobin Measurement in Nonanemic Women at First Booking: Effect of Altitude of Residence in Peru

Objective. To determine changes in hemoglobin concentration at second measurements after a normal hemoglobin concentration was detected at first booking during pregnancy at low and at high altitudes. Methods. This is a secondary analysis of a large database obtained from the Perinatal Information System in Peru which includes 379,816 pregnant women and their babies from 43 maternity units in Peru. Results. Most women remained with normal hemoglobin values at second measurement (75.1%). However, 21.4% of women became anemic at the second measurement. In all, 2.8% resulted with moderate/severe anemia and 3.5% with erythrocytosis (Hb>14.5 g/dL). In all cases Hb was higher as altitude increased. Risk for moderate/severe anemia increased associated with higher gestational age at second measurement of hemoglobin, BMI <19.9 kg/m2, living without partner, <5 antenatal care visits, first parity, multiparity, and preeclampsia. Lower risk for moderate/severe anemia was observed with normal high Hb level at first booking living at moderate and high altitude, and high BMI. Conclusion. Prevalence of anemia increases as pregnancy progress, and that a normal value at first booking may not be considered sufficient as Hb values should be observed throughout pregnancy. BMI was a risk for anemia in a second measurement.

Serum testosterone levels and score of chronic mountain sickness in Peruvian men natives at 4340 m

Life at high altitudes (>4000 m) is associated with higher erythropoiesis. Haemoglobin ≥21 g dl−1 is considered as excessive erythrocytosis and is a sign of chronic mountain sickness (CMS). The present study was designed to determine an association between serum testosterone (T) and serum oestradiol (E2) levels with the score of CMS. One hundred and seventeen men natives from low altitude (150 m) and 103 men natives from high altitude (4340 m) were studied. The presence of breathlessness or palpitations, sleep disturbance, cyanosis, dilatation of veins, paraesthesia, headaches, tinnitus and Hb ≥21 g dl−1, have been included for the CMS score. Men living at high altitude had higher CMS score (P < 0.001), serum T (P < 0.05) and serum E2 levels (P < 0.04) and had lower serum luteinising hormone levels (P < 0.005) than men living at sea level. At high altitude, the group with the highest CMS score (≥10) showed higher chronological age, SpO2, serum T and ratio T/E2 than the group with CMS score of ≤4. Some symptoms of CMS as sleep disorders and paraesthesia were more related to high serum T level; cyanosis was more related to higher haemoglobin values. In conclusion, higher serum T levels were associated to higher scores of CMS.

Association of hemoglobin values at booking with adverse maternal outcomes among Peruvian populations living at different altitudes

To determine hemoglobin values associated with adverse maternal outcomes among Peruvian populations at different altitudes.

Association between biofuel exposure and adverse birth outcomes at high altitudes in Peru: a matched case-control study.

Abstract Nearly one-third of the Peruvian population burns biofuels for cooking. Similarly, approximately one-third of this population lives at high altitudes. Cooking with biofuels and living at high altitudes have been implicated in adverse perinatal outcomes. This study attempted to determine the risk of low birth weight (LBW) and/or preterm delivery in relation to biofuel use in inhabitants at high altitudes in Peru. A matched-case study was performed in two high-altitude cities. All subjects (n = 190) were identified from public-hospital records. Cases were matched by hospital by week of birth and area of residence. Cases were defined as: women with an at-term but LBW newborn; or women with a preterm birth. Adjusted conditional logistic regression analyses were used to determine odds ratio. Fifty-two percent of the cases used biofuel whereas only 30% of the controls used biofuel. The use of biofuel for cooking was found to be strongly associated with increased risks of LBW, but was not significantly linked to preterm births.