RESUMO

Heart rate variability (HRV) has been recognised as a non-invasive method for assessing cardiac autonomic regulation. Aiming to characterize HRV changes at labour in women, we studied 10 minute ECG recordings from young mothers (n=30) at the third trimester of pregnancy (P) or during augmentation of labour (L) (n=30). Data of the L group were collected when no-contractions (L-NC) or the contractile activity (L-C) was manifested. Accordingly, the inter-beat interval (IBI) time series were processed to estimate relevant parameters of HRV such as the mean IBI (IBI¯), the mean heart rate HR¯, the root mean square of successive differences (RMSSD) in IBIs, the natural logarithm of high-frequency component (LnHF), the short-term scaling parameters from detrended fluctuation and magnitude and sign analyses such as (α1, α1(MAG), α1(SIGN)), and the sample entropy (SampEn). We found statistical differences (p<0.05) for RMSSD among P and L-NC/L-C groups (25 ± 13 vs. 36 ± 14/34 ± 16 ms) and for LnHF between P and L-NC (5.37 ± 1.15 vs. 6.05 ± 0.86 ms(2)). Likewise, we identified statistical differences (p<0.05) for α1(SIGN) among P and L-NC/L-C groups (0.19 ± 0.20 vs. 0.32 ± 0.17/0.39 ± 0.13). By contrast, L-NC and L-C groups showed statistical differences (p<0.05) in α1(MAG) (0.67 ± 0.12 vs. 0.79 ± 0.12), and SampEn (1.62 ± 0.26 vs. 1.20 ± 0.44). These results suggest that during labour, despite preserving a concomitant non-linear influence, the maternal short-term cardiac autonomic regulation becomes weakly anticorrelated (as indicated by α1(SIGN)); furthermore, an increased vagally mediated activity is observed (as indicated by RMSSD and LnHF), which may reflect a cholinergic pathway activation owing to the use of oxytocin or the anti-inflammatory cholinergic response triggered during labour.

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OBJECTIVE: To determine maternal hemoglobin behavior during pregnancy for middle altitude residents and to compare it with that reported in other populations with or without iron supplementation. MATERIALS AND METHODS: Hematological values from 227 pregnant women residing at 2 240 m altitude (Mexico City), with low obstetric and perinatal risk, and receiving supplementary iron, were compared with reference values obtained from other populations of pregnant women residing at different altitudes, after correcting for altitude. RESULTS: While the hemoglobin values for the first and second trimester of pregnancy in our studied population were similar to those reported for iron-supplemented populations (p>0.05), the third trimester values were similar to those reported for a population without this supplement (p>0.05). CONCLUSIONS: Despite receiving supplementary iron, hemoglobin values during pregnancy from women residing at middle altitude show similar behavior to that reported for pregnant women without iron supplementation.

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Objetivo. Determinar el comportamiento de la concentración de hemoglobina materna durante el embarazo en mujeres que residen en zonas de altitud media y compararlo con el reportado para poblaciones con y sin suplemento de hierro. Material y métodos. Valores hematológicos de 227 mujeres embarazadas, residentes a 2 240 metros de altitud (Ciudad de México), sin complicaciones obstétricas ni perinatales y recibiendo suplemento de hierro, fueron comparados con valores de referencia para mujeres embarazadas de otras altitudes. Resultados. Durante el primer y segundo trimestre, los valores de hemoglobina en nuestra población fueron similares a los observados en poblaciones con y sin suplemento de hierro (p>0.05). Durante el tercer trimestre, los valores fueron similares únicamente a los de poblaciones sin suplemento de hierro (p>0.05). Conclusiones. No obstante recibir hierro suplementario, el comportamiento de la concentración de hemoglobina durante el embarazo en mujeres residentes de la altitud media es similar al reportado para poblaciones sin hierro suplementario.

Objective. To determine maternal hemoglobin behavior during pregnancy for middle altitude residents and to compare it with that reported in other populations with or without iron supplementation. Materials and methods. Hematological values from 227 pregnant women residing at 2 240 m altitude (Mexico City), with low obstetric and perinatal risk, and receiving supplementary iron, were compared with reference values obtained from other populations of pregnant women residing at different altitudes, after correcting for altitude. Results. While the hemoglobin values for the first and second trimester of pregnancy in our studied population were similar to those reported for iron-supplemented populations (p>0.05), the third trimester values were similar to those reported for a population without this supplement (p>0.05). Conclusions. Despite receiving supplementary iron, hemoglobin values during pregnancy from women residing at middle altitude show similar behavior to that reported for pregnant women without iron supplementation.

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