A biobehavioral model for breastfeeding effects on return to menses postpartum in Javanese women

Abstract

This paper examines the effects of nursing behavior on the duration of lactation amenorrhea in 382 rural Indonesian women who experienced resumption of menses while breastfeeding or were breastfeeding and amenorrheic at the end of a two‐year prospective study. Three primary breastfeeding variables (number of night‐time nursing bouts, number of day‐time nursing bouts, and minutes per bout) were used to develop a behavioral model for breastfeeding. Four breastfeeding patterns were identified for these women. These were designated as: (1) low intensity, (2) medium‐low intensity, (3) medium‐high intensity, and (4) high intensity breastfeeding behavior. Menses resumed at medians of 11.2,16.0,17.6, and 20.8 months, respectively, for these groups. The relationships among the breastfeeding variables in the behavioral model and return to menses were developed and tested by life table and proportional hazards models. Ten per cent of the high intensity breastfeeding group (6 women) delayed menses between 33 and 52 weeks, while 90 per cent (56 women) postponed return of menses for over one year.     

Comparison of attitudes to breastfeeding among Spanish-born and Chinese-born postpartum women in Madrid

Background

Maternal breastfeeding is a practice that is associated with multiple health benefits for mothers and children. One of the lowest rates of breastfeeding has been observed among Chinese women who immigrate to high income countries. At present, there is a lack of comparative information between this group and that of Spanish-born women. Considering the relationship between the attitude of women towards breastfeeding and the initiation of breastfeeding, the aim of the study was to determine whether the attitude towards breastfeeding among Chinese postpartum women who have immigrated to Spain differs from that of Spanish-born postpartum women.

Methods

Cross-sectional study, with between-group comparison, of 73 postpartum Spanish-born and Chinese immigrant women admitted to the maternity units of “12 de Octubre” Hospital (Spain) between April and November 2016. Attitudes toward breastfeeding were analyzed using the Spanish or Chinese version of the Iowa Infant Feeding Attitude Scale (IIFAS). A wide set of socioeconomic, biological, working and attitudinal conditions were considered as covariates. The association between IIFAS and country of origin was assessed by three multiple linear regression models (B, SE, and 95% confidence interval were calculated).

Results

All Chinese women were first generation immigrants. Chinese-born women were four years younger than Spanish-born mothers, had a lower educational level, more frequently had a paid job (mainly self-employed), and planned to return to work almost two months earlier than Spanish-born mothers did. Most Chinese women did not breastfeed exclusively.Chinese immigrant women obtained scores of approximately 9 points less in the Iowa Infant Feeding Attitude Scale (IIFAS) when compared to Spanish-born women [95% CI -15.59, -2.48], after adjusting for the different socioeconomic, educational and work-related factors.

Conclusions

Chinese-born women resident in Spain present a lower score on the IIFAS, when compared to Spanish-born women, which implies a more negative attitude towards breastfeeding. The between-groups difference is consistent, even when adjusting for known confounders and other factors which could affect the attitude of the mothers. It is therefore striking that, despite being in Spain, Chinese-born women maintain these preferences/attitudes regarding breastfeeding, compared with Spanish-born women, who obtain overall high scores.

     

Birth spacing,breastfeeding, and early child mortality in a traditional Indian society: A hazards model analysis

Abstract

There are few studies of the interrelationships among breastfeeding, child spacing, and child mortality in traditional societies that incorporate extensive controls for social and demographic characteristics of the mother and child. In this paper, we investigate the impact of breastfeeding and the length of the preceding birth interval on early child mortality (defined as a death in the first two years of life) using data from a traditional society of India. Multivariate hazards models are used to analyze the data. Most prior analyses related the impact of breastfeeding duration to the duration of child survivability by taking breastfeeding as a fixed covariate. The present study has a methodological focus in the sense that breastfeeding information from retrospective survey data is treated as a time‐dependent covariate both as a status variate as well as a duration—with empirical findings compared across the two specifications. The effects of postpartum amenorrhoea and various other demographic and socioeconomic characteristics of mother and child are also studied. The results suggest that breastfeeding duration has a strong impact in reducing the relative risk of early child mortality; but it does not explain the effect of the length of the preceding birth interval on early child mortality.     

A model relating the incidence of meiotic trisomy to maternal age

A model is developed to explain the well-documented increase in the incidence of meiotic trisomies with increasing maternal age. This theoretical framework applies to all chromosomes, of which trisomy 21 (responsible for Down's syndrome in humans) is considered as a special case; the model can also be readily extended to trisomies of other mammals. The basic mechanism proposed links the hormonal environment of the oocyte to the durations of certain stages of meiosis. Changes in the hormonal environment, especially through aging, can slow the overall rate of meiosis, lengthening the interval from the resumption of meiosis in dictyotene until anaphase I. This extends the period in which homologous chromosomes are vulnerable to premature separation, increasing the probability of an unequal distribution of chromosomes in the first meiotic division. Testable predictions of the model are presented and discussed.     

The effect of high-intensity breastfeeding on postpartum glucose tolerance in women with recent gestational diabetes

Background

Although breastfeeding is expected to reduce the incidence of diabetes in women with gestational diabetes, the effect has not been clearly confirmed. We examined whether or not high-intensity breastfeeding reduces the incidence of abnormal glucose tolerance and investigated the effect of high-intensity breastfeeding on insulin resistance during the first year postpartum in Japanese women with current gestational diabetes.

Methods

In this retrospective study, we included women with gestational diabetes who underwent postpartum 75 g oral glucose tolerance test during the first year (12-14 months) postpartum from 2009 to 2011 at a single tertiary perinatal care center in Japan. High-intensity breastfeeding was defined as the condition in which infants were fed by breastfeeding alone or 80% or more of the volume. We investigated the effect of high-intensity breastfeeding on the prevalence of postpartum abnormal glucose tolerance and the postpartum homeostasis model of assessment of insulin resistance (HOMA-IR), after controlling for confounders, including prepregnancy obesity and weight changes during pregnancy and postpartum.

Results

Among 88 women with gestational diabetes, 46 (52%) had abnormal glucose tolerance during the postpartum period. High-intensity breastfeeding women (n?=?70) were significantly less likely to have abnormal glucose tolerance than non-high-intensity breastfeeding women (n?=?18) (46% vs. 78%, p?=?0.015). High-intensity breastfeeding was also associated with a lower HOMA-IR at 12-14 months postpartum than non-high-intensity breastfeeding (1.41?±?1.02 vs. 2.28?±?1.05, p?=?0.035). Those associations remained significant after controlling for confounders. At least six months of high-intensity breastfeeding had a significant effect on lowering both the abnormal glucose tolerance prevalence and HOMA-IR compared with non-high-intensity breastfeeding.

Conclusions

In Japanese women with gestational diabetes, high-intensity breastfeeding ≥6 months had a protective effect against the development of abnormal glucose tolerance during the first year postpartum through improving insulin resistance, independent of obesity and postpartum weight change.

     

Covariates of age at first birth in Guyana: a hazards model analysis

Analysis of data from the Guyana Fertility Survey on the trends and covariates of age at 1st birth among various birth cohorts of women ever in union indicates that an early entry into union is associated with young age at 1st birth and higher number of children born. Multivariate analysis showed that women with higher education, urban residence, and entry into 1st birth compared to others, and that young women are delaying their 1st birth for longer durations than older women. Work status of women before 1st birth and the starting age of union seem to be the 2 major contributory factors for age at 1st birth. Noticeably, the role of education has changed and is now more significant among younger cohorts than among older ones for 1st birth timing.     

Breast-feeding, social variables, and infant mortality: a hazards model analysis of the case of Malaysia

A hazards model was used to estimate the relative risks of infant mortality at various points during the 1st year of life among Malaysian infants who were breastfed for various durations. Data on infant mortality, breastfeeding, and social variables were derived from the retrospective Malaysian Family Life Survey. To provide adequate samples in subperiods of the 1st year of life, analysis intervals were constructed starting at ages 0, 2, 4, and 7 months, and including up to 13 months of exposure. The preferred models for the 1st 3 analysis intervals included breastfeeding as a predictor of infant mortality. It is a particularly significant determinant in the 1st and 3rd intervals. The relative risk of death among those who received food other than human milk was 6.26 compared to those who did not, and the infant who was never breastfed was 12 times more likely to die than the infant who was breastfed at some time. Infants breastfed for intermediate durations had intermediate effects estimates. In each analysis interval, the regression coefficient for unsupplemented breastfeeding was of larger magnitude than that for supplemented breastfeeding. Overall, this study shows that breastfeeding is an important determinant of infant mortality in Malaysia. Studies with larger samples are urged to confirm the preliminary finding of a monotonic relationship between breastfeeding duration and lower infant of mortality risks. However, this analysis demonstrates the utility of hazard model methodology as a powerful tool for calculating relative risk estimates when the sample size is relatively small and there are numerous covariates.     

Cytomorphological analysis of uterine cervical pap smears in relation to human papillomavirus infection in Indonesian women

Objective: Cervical cancer is the number one cause of cancer-associated death in Indonesian women (30/100,000 annually), where no screening program is present. The Papanicolaou test is widely accepted as an effective screening method for cervical neoplasia detection and often shows certain cytological features associated with human papillomavirus (HPV) infection. Especially in developing countries, cytological investigation is still the method of choice as compared to the frequent use of HPV DNA testing in western countries. Study Design: In the present study, we investigated the validity of the use of cytomorphological changes as a marker for HPV infection. A total of 140 smears collected in three different areas in Indonesia (Jakarta, Tasikmalaya and Bali) were analyzed. HPV DNA testing was performed using INNO-LiPA assays. Results and Conclusions: We found a highly significant association of classical koilocytosis, multinucleated cells, dyskeratosis-parakeratosis, nuclear membrane, enlarged nuclei, moderate/strong hyperchromasia and chromatin pattern with HPV positivity. Using classical and nonclassical cytomorphological parameters we found an overall sensitivity of 42% and a specificity of 90%. The combination of classical and nonclassical parameters led to a higher sensitivity of HPV positivity prediction. These results are of importance for cytologists in developing countries as molecular HPV testing still poses a major financial, logistic and expertise problem.     

Changes in age at marriage of women in rural north India.

There has been a dramatic increase in age at marriage for women in a rural area of north India. Age at marriage rose from under 12 years before 1930 to about 19 years in 1988, mainly as a result of socioeconomic development and advances in education of women.     

Physiological predictors of leptin vary during menses and ovulation in healthy women

Although research has shown interactions between the reproductive system and energy homeostasis, it is not clear how environmental or behavioral factors may factor into these associations. Here we aimed to determine how changes in reproductive state (i.e., phase of the menstrual cycle) and other behavioral and physiological factors may influence leptin levels in healthy women, as well as how sexual activity may play a role in leptin modulation. We collected serum and saliva from 32 healthy women and measured leptin, estradiol, and progesterone. Participants also completed surveys of demographics, health and sexual behaviors, and physical activity. Leptin was predicted by meals per day and missed meals at both menses and ovulation. However, estradiol and physical activity were stronger predictors of leptin at menses, while sexual activity was a stronger predictor of leptin at ovulation. These findings suggest that predictors of serum leptin, and possibly energy storage and expenditure, vary across the menstrual cycle.     

Prospective study on the association between harm avoidance and postpartum depressive state in a maternal cohort of Japanese women

Background

Recent studies have displayed increased interest in examining the relationship between personality traits and the onset, treatment response patterns, and relapse of depression. This study aimed to examine whether or not harm avoidance (HA) was a risk factor for postpartum depression measured by the Edinburgh Postnatal Depression Scale (EPDS) and the state dependency of HA.

Methods

Pregnant women (n=460; mean age 31.9±4.2 years) who participated in a prenatal program completed the EPDS as a measure of depressive state and the Temperament and Character Inventory (TCI) as a measure of HA during three periods: early pregnancy (T1), late pregnancy (around 36 weeks), and 1 month postpartum (T2). Changes in EPDS and HA scores from T1 to T2 were compared between the non depressive (ND) group and the postpartum depressive (PD) group.

Results

There was no significant difference in the level of HA between the ND and PD groups at T1. In the ND group, EPDS and HA scores did not change significantly from T1 to T2. In the PD group, both scores increased significantly from T1 to T2 (EPDS, p<0.0001; HA, p<0.048). In the ND and PD groups, a significant positive correlation was observed in changes in EPDS and HA scores from T1 to T2 (r=0.31, p=0.002).

Conclusions

These results suggest that HA cannot be considered a risk factor for the development of postpartum depression measured by EPDS. Furthermore, HA may be state dependent.     

The effect of Trypanosoma vivax infection on late pregnancy and postpartum return to cyclicity in Boran cattle

A study was designed to examine the effect of infection with Trypanosoma vivax KETRI 2501 on the maintenance of pregnancy and postpartum return to reproductive function in susceptible Galana (n = 6) and trypano-tolerant Orma Boran (n = 6) heifers during the third trimester of pregnancy. Of the 12 study animals, 3 Galana and 3 Orma Boran heifers served as controls. One of 3 Galana heifers calved prematurely with subsequent perinatal loss. Of the 2 heifers that produced live calves, 1 calf died shortly after birth, while the other survived. Two of 3 Orma heifers calved prematurely and all 3 calves died shortly after birth. The 6 control heifers produced live calves at term, all of which survived. Infection with T. vivax during the third trimester of pregnancy delayed the resumption of ovarian activity after calving, with the Ormas taking a significantly (P < 0.05) shorter time from calving to ovulation. There was no clear evidence that premature birth was associated with pathological changes in reproductive organs. Results from this study demonstrated that infection with pathogenic T. vivax during late pregnancy influenced the outcome of pregnancy in both susceptible Galana and trypano-tolerant Orma Boran heifers, resulting in premature births, perinatal loss, retained placentae, low birth weights and a prolonged period to the onset of postpartum ovarian activity.     

Effects of age on testosterone responses to resistance exercise and musculoskeletal variables in men

This study compared serum total testosterone (TT) and free testosterone (FT) responses of young (20-26 years, n = 8), middle-aged (38-53 years, n = 7), and older (59-72 years, n = 9) men to resistance exercise. We also examined the relationships between testosterone (T) levels and strength, bone mineral density (BMD), and body composition variables for each age group. Subjects were tested for isotonic muscular strength (1 repetition maximum [1RM]), BMD (dual-energy x-ray absorptiometry [DXA]) and body composition (DXA). Each group performed an acute exercise protocol (3 sets, 10 repetitions, 80% of 1RM, 6 exercises). Blood samples were obtained at baseline, immediately postexercise, and 15 minutes postexercise for the TT and FT assays. The older age group had significantly (p < 0.05) lower T levels than the young group, but each group exhibited an increase (p < 0.05) in TT and FT immediately postexercise. Total T and FT were significantly correlated (p < 0.05) with strength in middle-aged and older men and with bone-free lean tissue mass in older men. In conclusion, middle-aged and older men showed similar relative T responses to those of younger men to a single bout of high-intensity resistance exercise. However, T levels were related to strength and muscle mass only in middle-aged or older men. On a practical application level, older men can complete a high-intensity resistance exercise program resulting in spikes in T that may attenuate age-related muscle and BMD loss.     

The effects of adrenalectomy and corticosterone replacement on maternal memory in postpartum rats

Hormones associated with parturition prime rats to behave maternally, although hormonal changes are not necessary for these behaviors to occur. Experience with pups after birth enhances maternal responsiveness after a period of isolation, creating a maternal memory. The purpose of this study was to determine the role of corticosterone in the formation of maternal memory. Adrenalectomy or sham surgeries were performed in late gestation with corticosterone or vehicle pellets being given to adrenalectomized rats. Pups were removed immediately following parturition, and half of the rats received 4 h of pup experience, while the other half received only brief pup experience associated with parturition. Ten days following pup experience, foster pups were given to all rats. Latency to become maternal and maternal behaviors on the first 2 days of re-exposure and the first two maternal days were recorded. Among adrenalectomized rats given corticosterone, 4-h experience with pups decreased maternal latency when compared to brief experience with pups. This maternal experience effect was not found in comparisons between adrenalectomized rats not given corticosterone. In addition, corticosterone decreased latencies regardless of pup experience. Corticosterone also increased maternal behavior upon initial exposure to foster pups. In conclusion, corticosterone enhanced maternal memory and initial maternal behavior in postpartum rats.     

The effects of maternal immunity and age structure on population immunity to measles

Theoretical Ecology - Measles was successfully eradicated in the Pan-American Health Region in 2002. However, maintenance of elimination in parts of Africa, Europe, the USA, and other regions is...     

A measure of explained risk in the proportional hazards model

A measure of explained risk is developed for application with the proportional hazards model. The statistic, which is called the estimated explained relative risk, has a simple analytical form and is unaffected by censoring that is independent of survival time conditional on the covariates. An asymptotic confidence interval for the limiting value of the estimated explained relative risk is derived, and the role of individual factors in the computation of its estimate is established. Simulations are performed to compare the results of the estimated explained relative risk to other known explained risk measures with censored data. Prostate cancer data are used to demonstrate an analysis incorporating the proposed approach.     

A note on path-based variable selection in the penalized proportional hazards model

We propose an efficient and adaptive shrinkage method for variableselection in the Cox model. The method constructs a piecewise-linearregularization path connecting the maximum partial likelihoodestimator and the origin. Then a model is selected along thepath. We show that the constructed path is adaptive in the sensethat, with a proper choice of regularization parameter, thefitted model works as well as if the true underlying submodelwere given in advance. A modified algorithm of the least-angle-regressiontype efficiently computes the entire regularization path ofthe new estimator. Furthermore, we show that, with a properchoice of shrinkage parameter, the method is consistent in variableselection and efficient in estimation. Simulation shows thatthe new method tends to outperform the lasso and the smoothly-clipped-absolute-deviationestimators with moderate samples. We apply the methodology todata concerning nursing homes.     

Variation and classification of human age patterns of mortality: analysis using competing hazards models

The structure of variation in human mortality patterns is explored using a five-parameter competing hazards model and standard multivariate taxonomic procedures. The data consist of 281 national life tables representing a wide range of environmental and cultural regions of the world. A general or average age pattern of mortality was generated for the entire sample using multiple regression procedures. A K mean cluster analysis conducted on the residuals of the regression analysis identified seven distinct models of mortality that differ in characteristic ways from the general pattern. Four of the seven clusters have age patterns of mortality similar to the north, east, south, and west regions of the Coale and Demeny model life tables. The remaining three clusters represent regions of the world and age patterns of mortality that are not represented in the Coale and Demeny model life tables.