Does hypoxia impair ovarian function in Bolivian women indigenous to high altitude?

Fertility appears to be reduced in at least some high altitude populations relative to their counterparts at lower elevations. Inferring from the difficulties with reproduction of newcomers to high altitude and from animal experiments, it has been hypothesized that this apparent reduction is the result of hypoxia acting to reduce fecundity and/or increase fetal loss. In humans, however, several behavioral as well as biological factors may affect fertility levels. These many factors have been organized by demographers into a framework of seven proximate determinants that includes fecundability (the monthly probability of conception) of which successful ovulation is one component. To test whether ovarian function is impaired in women indigenous to high altitude, we measured salivary progesterone (P) in a sample (n = 20) of Quechua women (aged 19-42 years) residing at 3,100 m. It was found that mean luteal P = 179 pmol/L and mean midluteal P = 243 pmol/L, levels that fall about midway in the range of known values for several populations and are higher than some lower altitude populations. These findings suggest that hypoxia does not appear to significantly impair ovarian function in those with lifelong residence at high altitude. There are, however, several factors common to many high altitude populations that may act to reduce fecundability and fertility including intercourse patterns (affected by marriage and migration practices), prolonged lactation, dietary insufficiency, and hard labor.

Brief communication: effect of coca-leaf chewing on salivary progesterone assays.

Although there is evidence for reduced fertility in Andean and Himalayan populations at higher altitudes, factors other than hypoxia may be primarily responsible. A valuable approach in the investigation of these fertility determinants is the use of salivary steroid assays. However, coca-leaf chewing--a ubiquitous practice among high altitude Andean populations--has negative consequences for the accurate measurement of ovarian steroids. This report evaluates the effects of coca-leaf chewing on assays of salivary progesterone. Study participants include naive and habitual users of coca leaf from La Paz and El Alto, Bolivia. Approximately 300 saliva samples were collected immediately before, during, and after coca-leaf chewing. The series includes samples with and without the alkaloid enhancer typically used by coca-leaf chewers. Coca chewing produces false salivary progesterone values that mimic luteal phase values. On the basis of this study, an appropriate protocol is developed for the collection of salivary samples in coca-leaf chewing populations. These results verify the feasibility of salivary assays, even for very difficult field conditions, and highlight the necessity of establishing suitable collection procedures before full field implementation of saliva sampling.

Cerebral blood flow in the newborn infant: comparison of Doppler ultrasound and 133xenon clearance.

Two techniques of Doppler ultrasound examination, continuous-wave and range-gated, applied to the anterior cerebral artery and to the internal carotid artery, were compared with 133xenon clearance after intravenous injection. Thirty-two sets of measurements were obtained in 16 newborn infants. The pulsatility index, the mean flow velocity, and the end-diastolic flow velocity were read from the Doppler recordings. Mean cerebral blood flow was estimated from the 133Xe clearance curves. The correlation coefficients between the Doppler and the 133Xe measurements ranged from 0.41 to 0.82. In the subset of 16 first measurements in each infant, there were no statistically significant differences between the correlation coefficients of the various Doppler ultrasound variables, but the correlation coefficients were consistently lower for the pulsatility index than for mean flow velocity or end-diastolic flow velocity, and they were consistently higher for the range-gated than for the continuous-wave Doppler technique.

A scoring system to predict outcome following neonatal seizures.

Ninety-six newborn infants with seizures were scored during the initial hospitalization on abnormality of EEG, neurologic examination, etiology of seizures, length of seizure, type of seizure, and birth weight under or over 1,500 gm. At 3 months, corrected for gestational age, the 80 surviving infants were scored on abnormality of current EEG, neurologic examination, etiology of seizure, presence or absence of seizure since hospital discharge, and birth weight under or over 1,500 gm. At age 10 months, 76 of 77 surviving infants were evaluated with the Gesell Developmental Inventory, physical examination, and neurologic examination. Chi square analysis documented that the scoring system was an accurate predictor of those infants with seizure disorders, mental retardation, and motor dysfunction. The score may assist the clinician in making decisions in regard to anticonvulsant therapy during initial hospitalization or at age 3 months.

Transcephalic impedance in the neonate: an indicator of intracranial hemorrhage, asphyxia, and delayed maturation.

Increased transcephalic impedance readings (greater than 3 SD) were recorded in 13 asphyxiated infants 35 weeks or more in gestation, and in 13 preterm infants 34 weeks or less in gestation and with intracranial hemorrhage (greater than 2 SD). Six infants had decreased TCZ recordings in the weeks following intracranial hemorrhage, without ultrasound evidence of ventricular enlargement. TCZ provides quick, inexpensive, noninvasive indication of tissue necrosis, moderate-to-severe intracranial hemorrhage, and delayed brain maturation.