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At least 415 records · Page 23Linked to original sources
PubMed1994

Progestogen-only contraceptives during lactation: I. Infant growth. World Health Organization Task force for Epidemiological Research on Reproductive Health; Special Programme of Research, Development and Research Training in Human Reproduction.

Growth, development and health of infants whose mothers used progestogen-only contraceptives during lactation were examined in a prospective, non-randomized study carried out in seven centres in five countries (Egypt, Thailand, Kenya, Chile and Hungary). The results on growth are reported here. Breastfeeding women requesting effective contraception were admitted to the study at six weeks postpartum. Infants of acceptors of progestogen-only methods (pill, DMPA, NET-EN or NORPLANT implants) and non-hormonal methods (IUD, barrier methods or sterilization) formed the study groups. The follow-up was at monthly intervals until the end of the first postpartum year. Participating in the study were 2466 mother-infant pairs. The mean duration of exclusive breastfeeding varied from 68 to 159 days, but did not differ significantly between study groups within centres. In anthropometric measures (weight, arm circumference and triceps skinfold), the mean rates of change varied over time as expected, and across the centres. However, there were very few statistically significant differences in these rates of change between groups within centres. Since a large number of statistical comparisons were made, and there was no consistency either across centres, over time, or in the direction of the differences, we conclude that in this study, the progestogen-only contraceptives used during lactation did not adversely affect infant growth.

Adolescent↗
PubMed1994

Progestogen-only contraceptives during lactation: II. Infant development. World Health Organization, Task Force for Epidemiological Research on Reproductive Health; Special Programme of Research, Development, and Research Training in Human Reproduction.

Growth, development and health of infants whose mothers used progestogen-only contraceptives during lactation were examined in a prospective, non-randomized study that was carried out in seven centres in five countries (Egypt, Thailand, Kenya, Chile and Hungary). The results on development are reported here. Breastfeeding women requesting effective contraception were admitted to the study at six weeks postpartum. Infants of acceptors of progestogen-only methods (pill, DMPA, NET-EN or NORPLANT implants) and non-hormonal methods (IUD, barrier methods or sterilization) formed the study groups. The follow-up was at monthly intervals until the end of the first postpartum year. At each visit, the infant examination included, among other things, a set of developmental tests covering the following areas: gross motor, vision and fine motor, hearing, language and concept development, and self help and social skills. Participating in the study were 2466 mother-infant pairs. The comparisons between the study groups were carried out within centres using life table methods and Cox-model analysis having the time to first passing the test as the criterion. There were altogether 247 comparisons between the study groups. Thirty-two (13%) of these comparisons showed statistically significant differences: 20 differences showed that the infants in the progestogen-only groups passed the tests at an earlier age and 12 at a later age than infants in the non-hormonal groups. Since no consistent trends were observed across the centres, we conclude that in this study the progestogen-only contraceptives used during lactation did not adversely affect infant development.

Adolescent↗
PubMedDate not supplied

Using a computer color-matching system in color reproduction of porcelain restorations. Part 2: Color reproduction of stratiform-layered porcelain samples.

Computer color matching is an excellent method for reproducing certain colors of various objects using a spectrophotometer and a computer. In this study the authors attempted to reproduce the color of layered porcelain samples according to the computer color-matching formulation, wherein a computer color-matched sample is made and compared with the target sample. The color differences between the computer color-matched samples (opaque/dentin and opaque/dentin/enamel) and the target samples approximated 1.0, and the samples were indistinguishable by visual observation. The spectral reflectance curves were also very similar.

Computer-Aided Design↗
PubMed1998

Assisted reproduction by intracytoplasmic sperm injection: a survey on the clinical experience in 1994 and the children born after ICSI, carried out until 31 December 1993. ESHRE Task Force on Intracytoplasmic Sperm Injection. European Society for Human Reproduction and Embryology.

The second report of the ESHRE Task Force on ICSI describes the outcome of 13,666 ICSI cycles carried out in 1994 by 90 centres in 24 countries. Most cycles used ejaculated spermatozoa (94.4%) while epididymal and testicular spermatozoa were used in 4.1% and 1.5% of the cycles. Outcome measures in the three types of spermatozoa included the number of: (i) intact oocytes after ICSI; (ii) normally fertilized oocytes; (iii) transferred and frozen embryos; (iv) embryo transfers and (v) cycles with positive serum HCG. The evolution of the pregnancies was analysed in terms of pregnancy losses and clinical pregnancies. The results of ICSI with spermatozoa from the ejaculate was analysed according to the year that ICSI started in the different centres. The survey also reports the follow-up of children born after ICSI carried out until 31 December 1993. A total of 455 pre- and postnatal karyotypes revealed the presence of nine abnormal karyotypes. Twenty-four centres reported on 807 ICSI children: 763 using ejaculated spermatozoa, 36 using epididymal spermatozoa and eight using testicular spermatozoa. Sixteen major congenital malformations were reported.

Adult↗
PubMed1997

[The study on the epidemiological features and risk factor of Chlamydia trachomatis reproductive tract infection (CTRTI) among 664 married women at reproductive age in rural areas].

The infection rate and risk factors of CTRTI among 664 married women at reporductive age in rural areas in Chengjiang county, Yunnan province were investigated. Specimens of cervical swab were detected for CT antigen using Chlamydia EIA(Syva co., USA). The selection of major risk factors was through Logistic regression and chi 2-test. The results showed that the overall infection rate of CTRTI was 5.0%, with 60.6% of these cases asymptomatic. The major risk factors include: spouse who has symptoms of RTIs; history of others vaginitis; divorce; habit of washing face, feet and vulva with the same wash basin; age of menarche; amenorrhoea during lactation; low education and living in poverty.

Adult↗
PubMed1998

Effects of contraceptives on hemoglobin and ferritin. Task Force for Epidemiological Research on Reproductive Health, United Nations Development Programme/United Nations Population Fund/World Health Organization/World Bank Special Programme of Research, Development and Research Training in Human Reproduction, World Health Organization, Geneva, Switzerland.

The effects of combined oral contraceptives (OC), depot medroxyprogesterone acetate injections (DMPA), levonorgestrel subdermal implant (Norplant), copper-containing intrauterine devices (copper IUD), and Chinese stainless steel ring IUD on hemoglobin and ferritin were studied in 18-40-year-old, nonpregnant, and nonlactating women in seven countries (Bangladesh, Chile, China, the Dominican Republic, Pakistan, Thailand, and Tunisia). Data from 2507 women were analyzed. The study had a cross-sectional component in which 1295 current users of the contraceptive methods were compared with 1212 women initiating use of contraceptives. The results of this component showed that the current users of hormonal contraceptive methods generally had higher hemoglobin and ferritin levels than the noncontraceptors. The differences between women using hormonal contraceptive and noncontraceptors in mean values for hemoglobin varied between 3 and 6 g/L and for ferritin between 2 and 18 g/L. The current users of copper IUD had higher hemoglobin levels (difference in mean levels of 3 g/L), but lower ferritin levels (difference of 10 g/L) than noncontraceptors. Current use of the stainless steel ring had an adverse effect on both hemoglobin and ferritin. In a longitudinal component of the study, 285 anemic women (hemoglobin between 80 and 120 g/L at the time of initiation of contraception)--a subgroup of the cross-sectional component--were followed-up at 3, 6, and 12 months after initiation. In this component, significant mean increases of hemoglobin at 12 months were observed among the users of oral contraceptives and DMPA, but not among users of copper or stainless steel ring IUD. It is concluded that hemoglobin and ferritin levels are influenced by the use of contraceptives and that the hormonal contraceptives included in the present study have a beneficial effect on these parameters. The effects of copper IUD on hemoglobin and ferritin should be studied further.

Adolescent↗
PubMed2002

Allocation of resources to reproduction in Styrax obassia in a masting year.

An analysis is presented of three possible pathways of reproductive allocation, namely, allocation of resources to reproductive organs from reproductive shoots, from non-reproductive shoots and from the main trunk. These pathways were examined by comparing the amount of storage starch in reproductive shoots, non-reproductive shoots and the main trunk in Styrax obassia, a typical masting tree species, during a year of little flowering (1999) and in a mass-flowering year (2000). In addition, we measured rates of light-saturated photosynthesis in leaves of reproductive and non-reproductive shoots to examine the contribution of photosynthetic production to reproductive costs. In both the main trunk and non-reproductive shoots the pattern of seasonal variation in the amount of starch did not differ between 1999 and 2000. However, in the mass-flowering year, the amount of starch in the reproductive shoots was less than that in non-reproductive shoots during the growing season. Thus, reproductive shoots bore most of the cost of reproduction, although non-reproductive shoots and the main trunk also bore some of the cost. Mass-based rates of light-saturated photosynthesis of the leaves of reproductive shoots were significantly higher than those of non-reproductive shoots during both the flowering and the fruiting period. However, leaves of reproductive shoots had a significantly smaller area, a lower mass per area, and lower concentrations of nitrogen than leaves of non-reproductive shoots, although the number of leaves did not differ between the two types of shoots. Therefore, the amount of photosynthate per shoot was significantly lower in reproductive shoots than in non-reproductive shoots. These results suggest that the cost of reproduction depends predominantly on storage starch in reproductive shoots, although it is still unclear how much photosynthate is allocated to reproductive organs from non-reproductive shoots.

Fertility↗
PubMed2006

The evolution of senescence and post-reproductive lifespan in guppies (Poecilia reticulata).

The study of post-reproductive lifespan has been of interest primarily with regard to the extended post-menopausal lifespan seen in humans. This unusual feature of human demography has been hypothesized to have evolved because of the "grandmother" effect, or the contributions that post-reproductive females make to the fitness of their children and grandchildren. While some correlative analyses of human populations support this hypothesis, few formal, experimental studies have addressed the evolution of post-reproductive lifespan. As part of an ongoing study of life history evolution in guppies, we compared lifespans of individual guppies derived from populations that differ in their extrinsic mortality rates. Some of these populations co-occur with predators that increase mortality rate, whereas other nearby populations above barrier waterfalls are relatively free from predation. Theory predicts that such differences in extrinsic mortality will select for differences in the age at maturity, allocation of resources to reproduction, and patterns of senescence, including reproductive declines. As part of our evaluation of these predictions, we quantified differences among populations in post-reproductive lifespan. We present here the first formal, comparative study of the evolution of post-reproductive lifespan as a component of the evolution of the entire life history. Guppies that evolved with predators and that experienced high extrinsic mortality mature at an earlier age but also have longer lifespans. We divided the lifespan into three non-overlapping components: birth to age at first reproduction, age at first reproduction to age at last reproduction (reproductive lifespan), and age at last reproduction to age at death (post-reproductive lifespan). Guppies from high-predation environments live longer because they have a longer reproductive lifespan, which is the component of the life history that can make a direct contribution to individual fitness. We found no differences among populations in post-reproductive lifespan, which is as predicted since there can be no contribution of this segment of the life history to an individual's fitness. Prior work on the evolution of post-reproductive lifespan has been dominated by speculation and correlative analyses. We show here that this component of the life history is accessible to formal study as part of experiments that quantify the different segments of an individual's life history. Populations of guppies subject to different mortality pressures from predation evolved differences in total lifespan, but not in post-reproductive lifespan. Rather than showing the direct effects of selection characterizing other life-history traits, post-reproductive lifespan in these fish appears to be a random add-on at the end of the life history. These findings support the hypothesis that differences in lifespan evolving in response to selection are confined to the reproductive lifespan, or those segments of the life history that make a direct contribution to fitness. We also show, for the first time, that fish can have reproductive senescence and extended post-reproductive lifespans despite the general observation that they are capable of producing new primary oocytes throughout their lives.

Aging↗
PubMed1992

Reproductive activity of Synosternus cleopatrae (Siphonaptera: Pulicidae) in relation to host factors.

Reproductive activity of Synosternus cleopatrae (Rothschild) infesting Gerbillus andersoni allenbyi Thomas was studied in a natural setting in Israel. Rodents were trapped and measured (weight and length), their sex was identified, and their reproductive status estimated. Their ectoparasites were removed, and fleas were dissected and their oocytes measured. Two indices of flea reproductive activity were analyzed: "reproductive status," which distinguished between gravid and nongravid females, and "reproductive intensity," which was estimated as the sum over the two largest oocytes of the products of oocyte length multiplied by oocyte width. Both indices showed that no reproduction took place between November and January, but reproduction was relatively stable during the rest of the year. Although flea reproductive activity differed significantly among individual hosts, only a small fraction of gerbils (10-15%) carried a significantly different proportion of reproductive fleas than their monthly sample proportion (based on all fleas regardless of hosts). All these hosts carried a lower proportion of reproductive fleas than their monthly sample proportion. The host's sex, but not reproductive status or age, had a significant effect on flea reproduction, expressed as a higher reproductive activity on male gerbils. Infestation burden expressed as ectoparasite counts was included in the statistical analysis. Only lice, Polyplax gerbilli Ferris, but not S. cleopatrae, Stenoponia tripectinata (Tiraboschi), and a total of five mesostigmatid Acari had a significantly negative association with S. cleopatrae reproductive activity. These relationships between S. cleopatrae reproductive activity and the host infestation burden do not support the hypothesis of modulation of S. cleopatrae reproduction by the infestation burden. However, differences in the reproductive activity of ectoparasites between their hosts may play a major role to generate the parasite clumped distribution. Thus, gerbil males probably carry more fleas than gerbil females because of the higher reproductive activity of S. cleopatrae on gerbil males.

Animals↗
PubMed2001

Dominance, reproduction and survival in banded mongooses: towards an egalitarian social system?

The banded mongoose, Mungos mungo, is a social species that forms multimale and multifemale family groups. Earlier studies suggest these family groups are relatively egalitarian with small differences in reproductive opportunities among individuals of different rank. In contrast, previous studies of other social mongooses have focused on species with more despotic control of reproduction (meerkats, Suricata suricatta, dwarf mongooses, Helogale parvula). In these species, the distribution of reproductive opportunities amongst individuals of different rank has met the predictions of reproductive skew theory: dominant individuals accrue greater reproductive benefits than subordinates, with subordinates breeding less often than dominants. In this paper we test how well two predictions of reproductive skew theory explain variance in measures of reproductive effort, and its correlates, in a wild population of banded mongooses in Queen Elizabeth National Park, Uganda. We measure dominance rank in males and females, and we investigate whether individuals of higher social rank accrue greater benefits than subordinates in terms of survival and reproduction. Banded mongoose dominance hierarchies showed linearity, but low reproductive skew. Rank was not significantly correlated with age. Furthermore, there were only small effects of dominance rank on nutritional levels, and no effects on reproduction and survival, suggesting that banded mongoose societies are indeed relatively egalitarian. No evidence of reproductive suppression was found and other forms of reproductive control were not observed. However, we do not exclude the possibility of increased reproductive competition in circumstances of higher ecological constraints. These findings show that reproductive skew theory is equally useful in explaining variation in reproduction in societies with low reproductive skew, as it is in explaining the allocation of reproductive effort in despotic social systems. Copyright 2001 The Association for the Study of Animal Behaviour.

Journal Article↗