Breast-feeding and post-partum amenorrhoea in Indonesia

The association between breast-feeding patterns and resumption of menses post-partum was examined in a prospective study in Indonesia. In order to examine these relationships directly in a longitudinal study, it was first necessary to distinguish among women who experienced infant mortality before menses resumed, women who weaned before menses resumed, and women who had return to menses while breast-feeding. Information on suckling patterns and menstrual status was collected by recall for 444 women at monthly visits for 2 years. Three main breast-feeding variables, minutes per episode, number of episodes per day, number of episodes per night, and other breast-feeding variables were derived for each woman, to give the average nursing pattern up to menses or the end of the study, which-ever came first. While high levels of nursing for each of these three main variables were found to be significantly related to delay in return of menses post-partum, the interactions between more minutes per episode, and more frequent day- and night-time feeds, were found to be the most important factors in the delay in onset of post-partum menstruation in those women whose menses resumed while still nursing or who remained amenorrhoeic and nursing at the end of the study.     

Determinants of breast-feeding and post-partum amenorrhoea in Orissa

A life table analysis is made of the duration of breast-feeding and post-partum amenorrhoea in Orissa, India, taking one variable at a time using data from a baseline survey of fertility and mortality (BSFM) conducted on the lines of the World Fertility Survey. Then a multivariate (proportional hazard) analysis showed that socioeconomic factors including residence, caste status and education influence the breast-feeding and post-partum amenorrhoea periods. There was no effect of maternal age on the length of breast-feeding, but mean length of post-partum amenorrhoea varied with age. The durations of breast-feeding and post-partum amenorrhoea are strongly related.     

Measurement of post-partum amenorrhoea in Bangladesh.

Reported information on the duration of post-partum amenorrhoea usually shows considerable number preference, particularly at 6-monthly intervals. This paper presents a technique for smoothing such amenorrhoea data using a modified exponential curve. An attempt has also been made to estimate the average number of months a mother is expected to remain amenorrhoeic.     

Nutrition, infant feeding and post-partum amenorrhoea in rural Bangladesh

The extent to which differences in the duration of postpartum amenorrhea among chronically malnourished women in rural Bangladesh are related to seasonal patterns of food supply, maternal nutrition, education, and patterns of infant feeding was investigated by application of multivariate hazards models with time-varying covariates. The data were derived from the Birth Interval Dynamics study in Matlab and covered close to 1800 births. Parity, education, season of birth, maternal weight, and infant supplementation all were found to affect the duration of postpartum amenorrhea among these women. Education of 5 or more years had a positive effect on the resumption of menses. Higher parity women, who were older, had longer periods of amenorrhea, as did women who gave birth in October-December. As a measure of nutritional status, the woman's weight at pregnancy termination showed a highly significant positive coefficient, indicating that improved maternal nutrition increased the likelihood of resuming menstruation. Food supplementation, which tends to decrease breastfeeding, also significantly increased the risk of resuming menstruation and had an effect independent of the other variables. When the data were analyzed by season, the most striking finding was the strong influence of education on children born during October-December (who are too young to be directly affected by the larger food supply at birth during the harvest season). The other seasons showed weaker effects of education and a stronger effect of supplementation, perhaps because these infants are older during the harvest season and thus can benefit from supplements.     

Continuously recorded suckling behaviour and its effect on lactational amenorrhoea.

The hypothesis that the month-specific rate of return to ovarian cyclicity after childbirth is causally related to suckling pattern was tested for a population of New Mexican women recruited within the service area of New Mexico Highlands University and for a nationwide USA subpopulation of women recruited through membership of the Couple to Couple League (CCL). Survival analysis for time-dependent covariates was used, and significant predictors of the first postpartum menses were found. Important differences were detected in the suckling pattern for the two groups and a 5:2 differential was found in their respective rates of menstrual cycle recovery. Although the two groups were comparable perinatally, daily and time-windowed breast-feeding performance fell off at twice the rate for the New Mexico population when contrasted with the CCL sample. For both populations, the introduction of solid feeds was a strong and significant predictor of returning menstrual cyclicity, independent of suckling pattern.     

Nursing does affect the duration of the post-partum to ovulation interval in cotton-top tamarins (Saguinus oedipus)

Reports on callitrichid monkeys have not revealed a significant effect of nursing on interbirth intervals or on post-partum to ovulation intervals. We examined 25 post-partum intervals in cotton-top tamarin females to determine whether nursing infants would affect the length of the post-partum to ovulation interval. Urinary LH/CG and oestrone conjugates were measured in urine samples collected in the 6 weeks after birth. The post-partum to ovulation interval is the number of days between parturition and the rise of urinary LH and oestrone conjugates associated with ovulation. There was an 84% conception rate post partum. Neither mother's parity nor sex of the infants influenced the length of the post-partum to ovulation interval. The post-partum to ovulation interval for females nursing 2 infants was twice as long as for those not nursing or nursing 1 infant (P less than 0.05). The range of post-partum to ovulation interval lengths was more variable in nursing than in non-nursing females (P less than 0.01). Females spent less than 50% of observed time in contact and less than 20% of observed time nursing their infants. Neither the number of tamarins within the family nor the amount of time the mother was in contact with infants correlated with the length of the post-partum to ovulation interval. However, there was a positive correlation between the percentage time that mothers nursed 1 infant at a time and the length of the post-partum to ovulation interval (r = 0.75, P less than 0.02). The underlying mechanisms of suckling-induced delay of ovulation are present in the cotton-top tamarin as in other primate species. However, these nursing effects do not cause the substantial delay in fertility post partum that is associated with non-callitrichid primates.     

The duration of lactational amenorrhoea in urban Bangladeshi women

The duration of lactational amenorrhoea, and infant feeding patterns and behaviour, were investigated in a sample of 97 mother-infant pairs living in a poor urban area of Dhaka, Bangladesh. A seven-hour time allocation method was used to determine the number of breast-feeding bouts and their duration. The seven-hour observation period was conducted on five occasions: at birth, 1 month, 4 months, 8 months and either 10 or 11 months. The median duration of lactational amenorrhoea was determined to be 24.07 weeks using survival analysis. Mothers who breast-fed their babies for longer and more frequently had, on average, a longer period of lactational amenorrhoea. There was no relationship between sociodemographic characteristics of the mother and duration of lactational amenorrhoea, nor was there any significant relationship between maternal anthropometry and birth weight of the baby and duration of lactational amenorrhoea, but there was a tendency for women with lower body mass index to have longer durations. Using the Cox proportional hazards model, the best predictor of duration of lactational amenorrhoea was the mean of months 0 and 1 durations of breast-feeding, adjusted for the mean frequencies for those months. The introduction of weaning food was also an important predictor.     

Aggressive behaviour and its relation to oviposition in the domestic fowl

Hens in battery cages behave differently from those housed in pens. A knowledge of the factors which govern the differences is important from both practical and theoretical viewpoints. Laying hens of two strains were housed in cages or pens and the incidence of aggression before and after laying was studied. In stable groups little aggression was seen, so a strange bird was introduced to stimulate aggressive behaviour. Under these circumstances the incidence in caged light hybrids rose considerably before oviposition and fell sharply afterwards. This pattern was not seen in light hybrids kept in pens, nor in medium hybrids, whether caged or penned. Other workers have shown that caged light hybrids may be in a state of frustration before laying, and it is postulated that pre-laying aggression is triggered by frustration rather than by hormonal changes.     

Endothermic warm-up in two species of sphecid wasp and its relation to behaviour

Abstract. The ability of two sphecid wasps, Bembix rostrata and B.zonata (Hymenoptera: Sphecidae), to warm up endothermically is demonstrated under laboratory conditions. Mean warm-up rates of B.rostrata are comparable to bees of similar weight. Despite endothermic ability, field observations reveal that B.rostrata are not active below 22C. From observations at the nectar-foraging site (clumps of Thymus vulgaris flowers) it is calculated that the energy resources available to wasps are sufficient to power endothermic warm-up at low temperatures. Alternative explanations for the absence of wasp activity at low temperatures, such as the risk of parasitism, are suggested. Endothermy may be used periodically to increase flight efficiency in response to added load, such as prey carried by females, and mates by males.     

Demographic and socioeconomic determinants of variation in food and nutrient intake in an Andean community

Understanding the sources of variation in a community's diet is vital for development work, as well as being a source of anthropological and cultural insights. Previous surveys in the South American Andes suggest that nutrient deficiencies may be widespread; however, such interpretations have remained tentative since variance in Andean populations' diet has not been thoroughly examined. In this paper we consider the variation in diet due to variation in age, sex, and socioeconomic status and variation attributed to inter- and intraindividual variation in the diet. One to six days of dietary data (mean = 3.1) were collected via 24 h recalls from 221 residents of a small, rural community in highland Ecuador. The contribution of various food groups to the diet varied with land holdings and age but not sex. For example, animal-derived foods contribute more and tubers contribute less to the diet of the households with ≥5 Ha, and sweets contribute more to the diet of children. The interindividual variation in energy and nutrient intake was low and the intraindividual variation high relative to developed countries. The consequence are twofold. First, because interindividual variability is low, group mean intake can be estimated relatively easily, facilitating group comparisons. Second, because intraindividual variation is high, individual nutrient intake cannot be easily estimated, which will decrease the ability to detect associations between nutrient intake and health measures. This knowledge of the sources of dietary variation can lead to better study and survey designs in the rural Andes and elsewhere in the developing world. Am J Phys Anthropol 105:407–417, 1998. © 1998 Wiley-Liss, Inc.     

Analysis of postpartum lactational amenorrhoea in relation to breast-feeding: some methodological and practical aspects.

A large multicentre epidemiological study was carried out by WHO between 1991 and 1995 to analyse the duration of lactational amenorrhoea in relation to breast-feeding. The main results of this analysis, which used classical statistical modelling, have been already published. However, some specific aspects of the postpartum fertility amenorrhoea and breast-feeding covariates, and more specifically the observed progressive exhaustion of the breast-feeding inhibitory effect on the reproductive axis, may justify a closer look at the validity of the statistical tools. Indeed, as has already been emphasized, analysis of large longitudinal data sets in reproduction often faces three difficulties: (i) the precise determination of the event of interest, (ii) the way to handle the time evolution of both the studied variables and their effect on the event of interest and (iii) the often discrete nature of the data and the associated problem of tied events. The first objective of the present work was to give additional insights into the estimation and quantification of the dynamics of the effect of breast-feeding over time, considering this covariate either as fixed or time-dependent. The second objective was to show how to perform the analyses using corresponding adapted procedures in widely available statistical packages, without the need for acquiring particular programming skills.     

Acid hydrolases of the rat uterus in relation to pregnancy, post-partum involution and collagen breakdown

1. The rat uterus contains acid cathepsin, beta-glucuronidase, beta-galactosidase, acid phosphatase and deoxyribonuclease II at concentrations comparable with those found in liver. Two non-hydrolytic uterine enzymes, cytochrome c oxidase and aspartate aminotransferase, display only 2-6% of the activity found in liver. 2. The concentrations of acid cathepsin and beta-glucuronidase are significantly decreased in pregnancy and increase 3-4-fold during post-partum involution. 3. The concentrations of beta-galactosidase and acid phosphatase are not decreased in pregnancy and increase only 2-3-fold during involution. 4. The concentrations of these four acid hydrolases increase linearly during the first 4 days post partum and reach their peak values at the same time that wet weight and collagen content fall to their lowest point. 5. The concentration of deoxyribonuclease is depressed in pregnancy but does not rise above normal in the post-partum period. 6. Only a small proportion of each hydrolytic activity can be isolated in the mitochondrial-lysosomal fraction of sucrose homogenates of the rat uterus. This proportion increases during involution. However, the extensive mitochondrial rupture occurring during homogenization indicates that the technique is probably too harsh to obtain a true measure of the proportion of lysosomes present in the intact tissue. 7. There are no significant changes in either the concentration or subcellular distribution of the five acid hydrolases in the livers of the experimental rats during pregnancy or involution. In each case the largest proportion of the activity is found in the mitochondrial-lysosomal fraction of liver homogenates. 8. The results are interpreted in terms of the lysosomal theory of intracellular digestion.     

The fish community of a high mountain stream in Taiwan and its relation to dam design

Synopsis The fish community of a high mountain stream in Taiwan was studied from 1988 to 1990 in a 16 km section of Ta-chia river where a new dam is planned for construction. There were 16 species of fish belonging to 7 families; 15 genera were recorded. Six species are endemic to Taiwan. The dominant species wereZacco pachycephalus, Acrosscheileus paradoxus andRhinogobius brunneus. The composition of fish fauna was different between the eight study sites. Adjacent sites did not show a higher similarity than remote ones. AdultZ. pachycephalus andA. paradoxus showed seasonal aggregation behavior in the stream. At two distinct sites, Kukan and Tungmau, these two species had similar breeding and stock composition patterns with an intensified production period of juveniles from late autumn to early winter and a low, but continuous production period of juveniles in summer months. This information suggest that fishes in the river have special adaptations to the typhoon season in summer and benthic algal blooming in winter. The similarity of fish community and the independent breeding sites of endemic fishes in Kukan and Tungmau also suggest that these are important factors to consider for conservation when the flooding area of a high mountain dam is designed.     

Variability of breast sucking, associated milk transfer and the duration of lactational amenorrhoea.

Quantitative relationships between physical parameters of sucking, milk transfer and the duration of amenorrhoea were examined in normal mother-baby pairs under exclusive breastfeeding. Sucking pressures were recorded twice on the second and once on the fifth month after birth, during complete breastfeeding episodes, by means of a catheter attached to the nipple and connected to a pressure transducer, the signals of which were analysed by computer. Babies were weighed before and after each sucking episode to estimate milk transfer. In the first nursing episode after noon, 2-month-old babies sucked from 140 to > 800 times during 4-15 min from the first breast, obtaining from 20 to > 100 g milk. The physical parameters of sucking and milk transfer exhibited high inter-individual but low intra-individual variabilities. There were significant differences in the physical parameters of sucking and milk transfer efficiency between first and second breast and between the second and fifth months after birth. Milk transfer efficiency was inversely correlated with time occupied by non-sucking pauses > or = 1.5 s, and was directly correlated with mean intersuck intervals in the first breast and with duration of the sucking episode, number of sucks, mean pressure and area under the pressure curve in the second breast. There was no correlation between the physical parameters of sucking and duration of lactational amenorrhoea (n = 62). However, significantly more mothers had amenorrhoea lasting > 180 days among those whose babies spent a longer proportion of the nursing episode in non-sucking pauses > or = 1.5 s. This finding indicates that sensory stimulation of the nipple produced during a nursing episode by stimuli other than sucking itself may have an important role in sustaining lactational amenorrhoea. It is concluded that nursing episodes have a complex structure that allows the development of a breastfeeding phenotype in each mother-baby pair, exhibiting important inter-individual variability. The present analysis does not support the contention that this source of variability accounts for the variability in the duration of lactational amenorrhoea.