Improved models for the relationship between age and the probability of trypanosome infection in female tsetse, Glossina pallidipes Austen.

Between 1990 and 1999, at Rekomitjie Research Station, Zambezi Valley, Zimbabwe, 29,360 female G. pallidipes were dissected to determine their ovarian category and trypanosome infection status. Overall prevalences were 3.45 and 2.66% for T. vivax and T. congolense, respectively, declining during each year as temperatures increased from July - December. Fits to age-prevalence data using Susceptible-Exposed-Infective (SEI) and SI compartmental models were statistically better than those obtained using a published catalytic model, which made the unrealistic assumption that no female tsetse survived more than seven ovulations. The improved models require knowledge of fly mortality, estimated separately from ovarian category distributions. Infection rates were not significantly higher for T. vivax than for T. congolense. For T. congolense in field-sampled female G. pallidipes, we found no statistical support for a model where the force of infection was higher at the first feed than subsequently. The long survival of adult female tsetse, combined with feeding at intervals ≤3 days, ensures that post-teneral feeds, rather than the first feed, play the dominant role in the epidemiology of T. congolense infections in G. pallidipes. This is supported by estimates that only about 3% of wild hosts at Rekomitjie were harbouring sufficient T. congolense to ensure that tsetse feeding off them take an infected meal, so that the probability of ingesting an infected meal is low at every meal.

Role of ovarian reserve markers, antimüllerian hormone and antral follicle count, as aneuploidy markers in ongoing pregnancies and miscarriages.

OBJECTIVE: To assess the role of two ovarian reserve markers, antimüllerian hormone (AMH) and antral follicle count (AFC), as markers of the background risk for fetal trisomy. DESIGN: Prospective study. SETTING: Tertiary referral hospital. PATIENT(S): Assessment was carried out either in ongoing pregnancies or miscarriages in our center. INTERVENTION(S): AFC was assessed transvaginally during a routine (11-13 weeks) or referral scan. AMH was determined either during the first-trimester maternal serum markers assessment or in cases referred for chorionic villi sampling after the invasive procedure. MAIN OUTCOME MEASURE(S): AMH reference ranges were constructed according to maternal age, and AMH- and AFC-derived ovarian ages were compared among three different cytogenetic groups (normal karyotype, autosomal trisomies, and other chromosomal anomalies) in both ongoing pregnancies and miscarriages. RESULT(S): In autosomal trisomies, the median AFC-derived ovarian age was 3-5 years above the median maternal age. No differences were observed between AMH-derived ovarian age and maternal age. CONCLUSION(S): AFC-derived ovarian biologic age reflects a more precise background risk for fetal aneuploidy that is not observed for AMH-derived age.

Antral follicle count as a marker of ovarian biological age to reflect the background risk of fetal aneuploidy.

STUDY QUESTION: Can antral follicle count (AFC) measured during pregnancy be used as a marker of ovarian age to assess the background risk of fetal aneuploidy? SUMMARY ANSWER: AFC was lower than expected according to maternal chronological age in trisomic pregnancies; therefore ovarian age could potentially reflect a more precise background risk of fetal aneuploidy screening. WHAT IS KNOWN ALREADY: The decline in a woman's reproductive function is determined by a decline in the ovarian follicle pool and the quality of oocytes. The quantitative status of ovarian reserve can be indirectly assessed by AFC, but the role of AFC as an aneuploidy risk marker in pregnant women has not been assessed yet. STUDY DESIGN, SIZE, DURATION: Our study comprised a prospective cohort including 1239 singleton pregnancies scanned before 14 weeks in our center during a 14-month period. PARTICIPANTS/MATERIALS, SETTING, METHODS: Reference ranges for AFC were constructed using 812 spontaneously conceived, chromosomally normal singleton ongoing pregnancies using the Lambda-Mu-Sigma method. The study population (n = 934) included 19 pregnancies with viable autosomal trisomies (trisomies 21, 18 and 13), 17 non-viable autosomal trisomies (other than 21, 18 or 13), 7 monosomies X, 1 sex trisomy and 3 triploidies (total n = 47 with chromosomal abnormalities). AFC in chromosomally abnormal pregnancies was plotted against the reference ranges. AFC multiple of the median was calculated according to the median AFC obtained by each year of age. MAIN RESULTS AND THE ROLE OF CHANCE: Sixty-eight percent of women carrying a pregnancy with viable trisomies and 65% with non-viable trisomies presented an AFC below the 50th percentile. The median ovarian age in viable trisomies and non-viable trisomies was estimated to be 3 and 6 years above than median maternal age, respectively. However, the median ovarian age in monosomies X and triploidies was not higher than median maternal age. LIMITATIONS, REASONS FOR CAUTION: We did not assess the intra- and inter-observer reliability, or use specific three-dimensional analysis which may have advantages over our two-dimensional study. In clinical practice, a drawback for assessing AFC during pregnancy is that transvaginal ultrasound is needed at the 11- to 13-week scan, when the transabdominal approach is used most commonly. Furthermore identifying ovaries by ultrasound during pregnancy could be challenging. WIDER IMPLICATIONS OF THE FINDINGS: Considering that AFC reflects ovarian aging, this 'ovarian biological age' could potentially reflect a more precise background risk of fetal aneuploidy. STUDY FUNDING/COMPETING INTEREST(S): This study was supported by PI 11/00685. Instituto de Salud Carlos III. Fondo de Investigación Sanitaria. No competing interests declared.

Ovarian reserve test: an impartial means to resolve the mismatch between chronological and biological age in the assessment of female reproductive chances.

Nowadays, the ovarian reserve (OR) is considered more important than chronological age to estimate female reproductive capability. We conducted a retrospective, observational, and cohort study in order to detect the best predictor marker of OR, ovarian response, chances to obtain high-quality embryos, and pregnancy after in vitro fertilization (IVF) cycle in elderly women. For all eligible patients (aged between 40 and 50 and admitted to their first IVF cycle for primary infertility), we investigated the biochemical parameters and ultrasound aspects of ovaries and how they affected IVF outcomes. Age, basal follicle-stimulating hormone, basal luteinizing hormone, and basal-17ß-estradiol are better related to the dose of gonadotropin used during a controlled ovarian stimulation cycle. Basal anti-Müllerian hormone (AMH), antral follicular count (AFC), and maximum serum level of 17ß-estradiol before pickup resulted the best predictors of chances to retrieve at least 6 oocytes (at least 3 in metaphase II) and to have at least 1 to 3 embryos. The basal AMH, AFC and maximum serum level of 17ß-estradiol before pickup continue to show higher correlation to pregnancy rate. The maximum endometrial thickness at pickup resulted important to predict the pregnancy rate and the chances to detect ongoing pregnancy. It seems mandatory to well define the ovarian biological age rather than the chronological one in women older than 40 years of age in order to give the best counseling and to choose the most appropriate IVF protocols.