Synthetic Cohort Life Tables Research Articles

State-level variation in the cumulative prevalence of child welfare system contact, 2015–2019

BackgroundPrior estimates of the cumulative risks of child welfare system contact illustrate the prominence of this system in the lives of children in the United States (U.S.). However, these estimates report national data on a system administered at the state and local levels and are unable to detail potential simultaneous geographic and racial/ethnic variation in the prevalence of these events. MethodsUsing 2015–2019 data from the National Child Abuse and Neglect Data System and Adoption and Foster Care Analysis and Reporting System, we use synthetic cohort life tables to estimate cumulative state- and race/ethnicity-specific risks by age 18 of experiencing: (1) a child protective services investigation, (2) confirmed maltreatment, (3) foster care placement, and (4) termination of parental rights for children in the U.S. ResultsIn the U.S., state-level investigation risks ranged from 14% to 63%, confirmed maltreatment risks from 3% to 27%, foster care placement risks from 2% to 18%, and risks of parental rights termination from 0% to 8%. Racial/ethnic disparities in these risks varied greatly across states, with larger disparities at higher levels of involvement. Whereas Black children had higher risks of all events than white children in nearly all states, Asian children had consistently lower risks. Finally, ratios comparing risks of child welfare events show these prevalences did not move in parallel, across states or racial/ethnic groups. ContributionThis study provides new estimates of spatial and racial/ethnic variation in children’s lifetime risks of maltreatment investigation, confirmed maltreatment, foster care placement, and termination of parental rights in the U.S., as well as relative risks of these events.

Childhood Prevalence of Involvement with the Child Protection System in Quebec: A Longitudinal Study

The goal of this study, the first of its kind in Canada, was to estimate the child lifetime prevalence of child protection involvement in Quebec. Using administrative and population data spanning 17 years, we performed a survival analysis of initial incidents of child protection reports, confirmed reports, confirmation of a child's security or development being compromised, and placement outside the home for one day or more. We found that before reaching the age of 18 years, over 18% of children were reported to child protection at least once, one in every ten children (10.1%) in the province had a report that led to the finding of their security or development being compromised, and over 5% were placed outside the home. We found that neglect was a primary concern in close to half (47.6%) of cases. By using a full population dataset, we obtained a more accurate prevalence estimate than studies using synthetic cohort life tables. These findings only captured initial incidents of involvement with child protection, meaning this study does not show the extent of recurrent involvement for some children. The findings reflect prior results showing that neglect is common in initial child protection involvement but less pervasive than has been shown in incidence studies, suggesting that recurrent child protection involvement is more driven by neglect than initial incidents are.

The Cumulative Prevalence of Congregate Care Placement for U.S. Children by Race/Ethnicity, 2019.

Congregate care placement is among the most consequential forms of foster care placement that youth can experience, as it means a removal from both the family of origin and a family setting more broadly. Unfortunately, little research has estimated how common this intervention is. In this article, we use data from the Adoption and Foster Care Analysis Reporting System (AFCARS) and synthetic cohort life tables to show what proportion of children ever placed in foster care will ever be placed in congregate care, what proportion of children in the entire population will ever be placed in congregate care, and how these proportions vary by state of residence and race/ethnicity. Our results support four main conclusions. First, roughly 15% of all children ever placed in foster care will experience congregate care placement. Second, among children who will ever be placed in foster care, the risk of congregate care placement peaks at age 16. Third, congregate care placement is highly stratified by race/ethnicity. Finally, there are vast geographic differences in both congregate care placement and ethno-racial disparities therein. Taken together, these findings enhance our understanding of the demography of the child welfare system with implications for research, policy, and practice.

Sex differentials in under five mortality in India in last two decades: Evidence from pooled NFHS data

Abstract Under Five Mortality Rate (U5MR) of a nation is widely accepted and a long-standing indicator of their children. In 2017, the sex-specific under-five mortality rate was 39 per 1,000 live births for male and 40 per 1,000 live births for females. India U5MR decrease from 124 per 1000 live birth in 1990 to 39 per 1000 live birth in 2017. According to NFHS, U5MR was 109 in 1992–93, 95 in 1998–99, 74 in 2005–06 and 50 in 2015–16. Sex differential in U5MR 6, 7, 11 and −8. Is there any sex differential in u5mr and relation between socioeconomic and u5mr. The dataset for this study comes from the three round of NFHS (National Family Health Survey) conducted during 1992–1993, 1997–1998 and 2015–2016. NFHS-1 and NFHS-2 used as append data. Synthetic cohort life table approach and multiple linear regression (fixed effect) model use. Sex differential in U5MR is increasing till 2005–06, after 2006, it is decreases. Sex differential in U5MR decrease most of the southern part, Literate, urban, Hindu, SC/ST and in non-SC/ST over time 1995–2015. Proportion of explained variation to overall unexplained variation in the model mainly explain by female U5MR at NSS level.

Cumulative Prevalence of Confirmed Maltreatment and Foster Care Placement for US Children by Race/Ethnicity, 2011-2016.

Objectives. To estimate the cumulative prevalence of confirmed child maltreatment and foster care placement for US children and changes in prevalence between 2011 and 2016.Methods. We used synthetic cohort life tables and data from the Adoption and Foster Care Analysis and Reporting System and the National Child Abuse and Neglect Data System and population counts from the Centers for Disease Control and Prevention.Results. US children's cumulative prevalence of confirmed maltreatment remained stable between 2011 and 2016 at about 11.7% (95% confidence interval [CI] = 11.6%, 11.7%) of the population and increased by roughly 11% for foster care placement from 4.8% (95% CI = 4.8%, 4.8%) to 5.3% (95% CI = 5.3%, 5.4%). American Indian/Alaska Native children experienced the largest change, an 18.0% increase in confirmed maltreatment risk from 13.4% (95% CI = 13.1%, 13.6%) to 15.8% (95% CI = 15.6%, 16.1%) and a 21% increase in foster care placement risk from 9.4% (95% CI = 9.2%, 9.6%) to 11.4% (95% CI = 11.2%, 11.6%).Conclusions. Confirmed child maltreatment and foster care placement continued to be experienced at high rates in the United States in 2012 through 2016, with especially high risks for American Indian/Alaska Native children. Rates of foster care have increased, whereas rates of confirmed maltreatment have remained stable.

The Cumulative Prevalence of Termination of Parental Rights for U.S. Children, 2000-2016.

Recent research has used synthetic cohort life tables to show that having a Child Protective Services investigation, experiencing confirmed maltreatment, and being placed in foster care are more common for American children than would be expected based on daily or annual rates for these events. In this article, we extend this literature by using synthetic cohort life tables and data from the Adoption and Foster Care Analysis and Reporting System to generate the first cumulative prevalence estimates of termination of parental rights. The results provide support for four conclusions. First, according to the 2016 estimate, 1 in 100 U.S. children will experience the termination of parental rights by age 18. Second, the risk of experiencing this event is highest in the first few years of life. Third, risks are highest for Native American and African American children. Nearly 3.0% of Native American children and around 1.5% of African American children will ever experience this event. Finally, there is dramatic variation across states in the risk of experiencing this event and in racial/ethnic inequality in this risk. Taken together, these findings suggest that parental rights termination, which involves the permanent loss of access to children for parents, is far more common than often thought.

Neighborhood inequality in the prevalence of reported and substantiated child maltreatment.

Prior research documents spatial concentration in the incidence of child maltreatment reported to and confirmed by Child Protective Services (CPS), but without estimates of the prevalence of such reports, the extent of CPS contact in different communities is unknown. To estimate the prevalence of CPS reports during early childhood and substantiated investigations during childhood for children living in different types of neighborhoods. Children who experienced CPS reports and substantiated investigations in Connecticut. This study uses synthetic cohort life tables to estimate the cumulative risk of CPS reports before age five and substantiated CPS investigations before age 18, by neighborhood poverty rate and neighborhood racial composition. The analysis reveals substantial stratification in the prevalence of CPS contact by the demographic characteristics of children's residential neighborhoods. For example, while 7% of children in low-poverty neighborhoods (under 10% poor) experience a substantiated CPS investigation at some point during childhood at 2014 and 2015 rates, this risk more than doubles to 17% for their peers in moderate-poverty neighborhoods (10-20% poor) and more than triples to 26% for their peers in high-poverty neighborhoods (over 20% poor). Similar trends emerge when examining CPS reports in early childhood as well as when comparing neighborhoods with different proportions of White residents. CPS reports and substantiated investigations are a widespread and disproportionately experienced life event for children in poor neighborhoods and children in non-White neighborhoods.

Lifetime Prevalence of Investigating Child Maltreatment Among US Children.

To estimate the lifetime prevalence of official investigations for child maltreatment among children in the United States. We used the National Child Abuse and Neglect Data System Child Files (2003-2014) and Census data to develop synthetic cohort life tables to estimate the cumulative prevalence of reported childhood maltreatment. We extend previous work, which explored only confirmed rates of maltreatment, and we add new estimations of maltreatment by subtype, age, and ethnicity. We estimate that 37.4% of all children experience a child protective services investigation by age 18 years. Consistent with previous literature, we found a higher rate for African American children (53.0%) and the lowest rate for Asians/Pacific Islanders (10.2%). Child maltreatment investigations are more common than is generally recognized when viewed across the lifespan. Building on other recent work, our data suggest a critical need for increased preventative and treatment resources in the area of child maltreatment.

Independent and combined effects of maternal smoking and solid fuel on infant and child mortality in sub-Saharan Africa.

To estimate the independent and combined risks of infant and child mortality associated with maternal smoking and use of solid fuel in sub-Saharan Africa. Pooled weighted data on 143 602 under-five children in the most recent demographic and health surveys for 15 sub-Saharan African countries were analysed. The synthetic cohort life table technique and Cox proportional hazard models were employed to investigate the effect of maternal smoking and solid cooking fuel on infant (age 0-11 months) and child (age 12-59 months) mortality. Socio-economic and other confounding variables were included as controls. The distribution of the main explanatory variable in households was as follows: smoking + solid fuel - 4.6%; smoking + non-solid fuel - 0.22%; no smoking + solid fuel - 86.9%; and no smoking + non-solid fuel - 8.2%. The highest infant mortality rate was recorded among children exposed to maternal smoking + solid fuel (72 per 1000 live births); the child mortality rate was estimated to be 54 per 1000 for this group. In full multivariate models, the risk of infant death was 71% higher among those exposed to maternal smoking + solid fuel (HR = 1.71, CI: 1.29-2.28). For ages 12 to 59 months, the risk of death was 99% higher (HR = 1.99, CI: 1.28-3.08). Combined exposures to cigarette smoke and solid fuel increase the risks of infant and child mortality. Mothers of under-five children need to be educated about the danger of smoking while innovative approaches are needed to reduce the mortality risks associated with solid cooking fuel.

More education, fewer divorces? Shifting education differentials of divorce in Taiwan from 1975 to 2010

Background: While social gradient in divorce has been explored in many Western societies, this issue has received less attention in Asia. Objective: Few existing studies offer evidence for how educational gradient in divorce shift from positive to negative in Asia. This study explores the changing divorce patterns by education for both sexes over the past four decades in Taiwan. Methods: Vital statistics of divorce since 1975 were used. Divorce rates were calculated and a synthetic cohort life table was also constructed to estimate the proportions of unions that remain intact with the duration-specific divorce rates observed in 2010. A separate life table estimating the actual marriage survivorship for the 1998 marriage cohort was also presented. Results: As Taiwan went through industrialization, the period findings show that a reversal in educational differential in divorce from positive to negative is observed for both sexes. Now the least educated men and women have become more vulnerable to union instability. Finally, synthetic cohort life table estimates indicate substantial educational differences in the proportions of recent marriages ending in divorce. Conclusions: The drastic increase in period divorce rates is accompanied by a reversal of educational gradient and expanding social inequality. Social gap in divorce rates expanded much faster among men than women across years. Given that remarriage rates for the disadvantaged are lower than the better educated, these patterns indicate that the disadvantaged is likely to spend an increasingly large proportion of their lives outside a marital union. Contribution: The divorce patterns revealed have critical implications for single-parent families, as well as family policies and social assistance.

Trends in neonatal mortality in Nigeria and effects of bio-demographic and maternal characteristics.

BackgroundNigeria’s efforts to reduce under-five mortality has been biased in favour of childhood mortality to the neglect of neonates and as such the literature is short of adequate information on the determinants of neonatal mortality. Whereas studies have shown that about half of infant deaths occur in the neonatal period. Knowledge of the determinants of neonatal mortality are essential for the design of intervention programes that will enhance neonatal survival. Therefore, this study was conducted to investigate the trends and factors associated with neonatal mortality in Nigeria.MethodsThis was a retrospective analysis of the reproductive history data collected in the Nigeria Demographic and Health Surveys (NDHS) for 1990, 2003, 2008 and 2013. Neonatal mortality rates were estimated as the probability of dying before 28 completed days using synthetic cohort life table techniques. Univariate and multiple Cox proportional hazards regression models were used to explore the effects of selected maternal and bio-demographic variables on neonatal mortality. The Hazard Ratio (HR) and its 95% Confidence Interval (CI) were estimated to prioritize obtained significant factors.ResultsNigeria neonatal mortality rate stagnated at 41 per 1000 live births between 1990 and 2013. There were rural-urban and regional differences with more deaths occurring in rural areas and northern regions. In 1990, antenatal care (HR = 0.76; CI = 0.61-0.95), facility delivery (HR = 0.69; CI = 0.53-0.90) and births interval less than 24 months (HR = 1.67; CI = 1.41-1.98) were significantly associated with neonatal deaths. Factors identified from the 2013 data were antenatal care (HR = 0.76; CI = 0.61-0.95), birth interval less than 24 months (HR = 1.67; CI = 1.41-1.98), delivery at health facility (HR = 0.69; CI = 0.53-0.90), and small birth size (HR = 1.72; CI = 1.39-2.14).ConclusionThere was little improvement in neonatal survival in Nigeria between 1990 and 2013. Bio-demographic and health care related characteristics are significant determinants of neonatal survival. Family planning should be intensified while government should improve the quality of maternal and child health services to enhance the survival of neonates.

Cumulative risks of foster care placement for Danish children.

Although recent research suggests that the cumulative risk of foster care placement is far higher for American children than originally suspected, little is known about the cumulative risk of foster care placement in other countries, which makes it difficult to gauge the degree to which factor foster care placement is salient in other contexts. In this article, we provide companion estimates to those provided in recent work on the US by using Danish registry data and synthetic cohort life tables to show how high and unequally distributed the cumulative risk of foster care placement is for Danish children. Results suggest that at the beginning of the study period (in 1998) the cumulative risk of foster care placement for Danish children was roughly in line with the risk for American children. Yet, by the end of the study period (2010), the risk had declined to half the risk for American children. Our results also show some variations by parental ethnicity and sex, but these differences are small. Indeed, they appear quite muted relative to racial/ethnic differences in these risks in the United States. Last, though cumulative risks are similar between Danish and American children (especially at the beginning of the study period), the age-specific risk profiles are markedly different, with higher risks for older Danish children than for older American children.

The prevalence of confirmed maltreatment among US children, 2004 to 2011.

Child maltreatment is a risk factor for poor health throughout the life course. Existing estimates of the proportion of the US population maltreated during childhood are based on retrospective self-reports. Records of officially confirmed maltreatment have been used to produce annual rather than cumulative counts of maltreated individuals. To estimate the proportion of US children with a report of maltreatment (abuse or neglect) that was indicated or substantiated by Child Protective Services (referred to as confirmed maltreatment) by 18 years of age. The National Child Abuse and Neglect Data System (NCANDS) Child File includes information on all US children with a confirmed report of maltreatment, totaling 5,689,900 children (2004-2011). We developed synthetic cohort life tables to estimate the cumulative prevalence of confirmed childhood maltreatment by 18 years of age. The cumulative prevalence of confirmed child maltreatment by race/ethnicity, sex, and year. At 2011 rates, 12.5% (95% CI, 12.5%-12.6%) of US children will experience a confirmed case of maltreatment by 18 years of age. Girls have a higher cumulative prevalence (13.0% [95% CI, 12.9%-13.0%]) than boys (12.0% [12.0%-12.1%]). Black (20.9% [95% CI, 20.8%-21.1%]), Native American (14.5% [14.2%-14.9%]), and Hispanic (13.0% [12.9%-13.1%]) children have higher prevalences than white (10.7% [10.6%-10.8%]) or Asian/Pacific Islander (3.8% [3.7%-3.8%]) children. The risk for maltreatment is highest in the first few years of life; 2.1% (95% CI, 2.1%-2.1%) of children have confirmed maltreatment by 1 year of age, and 5.8% (5.8%-5.9%), by 5 years of age. Estimates from 2011 were consistent with those from 2004 through 2010. Annual rates of confirmed child maltreatment dramatically understate the cumulative number of children confirmed to be maltreated during childhood. Our findings indicate that maltreatment will be confirmed for 1 in 8 US children by 18 years of age, far greater than the 1 in 100 children whose maltreatment is confirmed annually. For black children, the cumulative prevalence is 1 in 5; for Native American children, 1 in 7.

Cumulative Risks of Foster Care Placement by Age 18 for U.S. Children, 2000–2011

Foster care placement is among the most tragic events a child can experience because it more often than not implies that a child has experienced or is at very high risk of experiencing abuse or neglect serious enough to warrant state intervention. Yet it is unclear how many children will experience foster care placement at some point between birth and age 18. Using synthetic cohort life tables and data from the Adoption and Foster Care Analysis and Reporting System (AFCARS), we estimated how many U.S. children were placed in foster care between birth and age 18, finding support for three conclusions. First, up to 5.91% of all U.S. children were ever placed in foster care between their birth and age 18. Second, Native American (up to 15.44%) and Black (up to 11.53%) children were at far higher risk of placement. Foster care is thus quite common in the U.S., especially for historically disadvantaged racial/ethnic groups. Third, differences in foster care placement were minimal between the sexes, indicating that the high risks of foster care placement are shared almost equally by boys and girls.

Exploring variations in under-5 mortality in Nigeria using league table, control chart and spatial analysis

Under-5 mortality rate (U5MR) is the probability of a child born in a specific year or period dying before reaching the age of 5. Nigeria has a high rate of U5MR and accounts for a significant proportion of the high U5MR in sub-Sahara Africa. There are differences in health and social practice in the different states in Nigeria, coupled with the differences in developmental priorities of each State government. There is therefore the need to identify the states with high and low U5MR, to further explore the risk factors and make recommendations for planning. This study investigates variation in U5MR in Nigeria using Shewhart's theory of variation and control charts. We used data from the birth histories included in the 2008 Nigerian Demographic and Health Survey to estimate U5MR using a synthetic cohort life table. We plotted control charts of the proportion of under-5 mortality for the 37 states (included federal capital Abuja) in Nigeria. The Local Indicators of Spatial Association was used as a measure of the overall clustering and is assessed by a test of a null hypothesis. On average, more than 1 in every 10 children born in Nigeria (159 per 1000 live births) does not survive to their fifth birthday. Kwara and Osun states had the lowest U5MR (less than 60 per 1000 live births), while Jigawa, Kano, Sokoto, Niger and Adamawa states had the highest U5MR (more than 200 per 1000 live births). There is a wide variation in the U5MR between the 37 states. The funnel plot identifies 27 (73%) states within the 99% control limits indicating common-cause variation. Four states were above the upper control limit (higher than the average) and six states were below the lower control limit (lower than the average), indicating special-cause variation. U5MR is high in Nigeria; the rates are in three digits. There is a wide variation in the U5MR in Nigeria, with 27% showing evidence of special-cause variation which merits further investigation to identify possible causes. However, the vast majority of states (73%) are consistent with common-cause variation.

Association of maternal HIV infection with increase of infant mortality in Malawi

To determine the association between maternal HIV infection and infant mortality in Malawi. A synthetic cohort life table based on the birth history of 2618 childbirths during 1999 and 2004, from the subsample of 2020 mothers who completed interview and were tested for HIV virus in the 2004 Malawi Demographic and Health Survey was used. The survey collected socio-demographic and health data of a natural representative sample of women aged 15 to 49; and obtained voluntary counselling tests for HIV infection from one-third of the representatives of the sample. Associations of maternal HIV status and other factors with infant mortality were estimated using survival regression analysis and the results are presented as hazard ratios (HR) with level of statistical significance (P-value). Children born to HIV-infected mothers were more than two times as likely to die during infancy as those born to uninfected mothers (HR = 2.21; P < 0.01). Controlling for other risk factors and confounding factors for infant mortality further sharpened this relationship (HR = 2.70; P < 0.01). Boys are more likely to die in infancy than girls. Young mothers and mothers not receiving prenatal care, and low-birthweight children and children living in rural areas, particular so in the northern region, were associated with a higher risk of infant mortality. Maternal HIV infection is strongly associated with infant mortality in Malawi independent of many other factors. Results from this study suggest that the HIV/AIDS epidemic has had an enormous impact on child well-being, child survival and infant mortality. The impact increases as the HIV/AIDS epidemic matures and infection in mothers and adults increases.

Effect Of Maternal HIV Infection On Child Survival In Ghana

The purpose of this study was to measure the association between maternal HIV infection and infant mortality in Ghana. Using a censored synthetic cohort life table based on the birth history of 3639 childbirths during 1999-2003 obtained from the interviews of a nationally representative sample of 5691 women age 15-49 in 6251 households in the 2003 Ghana Demographic and Health Survey. The survey collected demographic, socioeconomic, and health data of the respondents as well as obtained voluntary counseling test for HIV infection from all eligible women. The effects of maternal HIV status and other factors on infant mortality were estimated using multivariate survival regression analysis and the results are presented as Hazard Ratios (HR) with 95% confident interval (95% CI). Children born to HIV infected mothers were three times as likely to die during infancy as those born to uninfected mothers (HR = 3.01; 95% CI: 1.64, 5.50). Controlling for other factors affecting infant mortality further sharpens this relationship (HR = 3.51; 95% CI: 1.87, 6.61). Not receiving antenatal care, low birth weight, and living in households that use high pollution cooking fuels were associated with a higher risk of infant mortality. Maternal HIV status is a strong predictor of infant mortality in Ghana, independent of several other factors. The results of this study suggest that HIV/AIDS epidemic has had great impact on child well-being and child survival. This impact tends to increase as the HIV/AIDS epidemic matures and infection in adults increases.

Use-Effectiveness of Oral Contraceptives by Demographic Characteristics

To determine which patients benefit the most from oral contraceptives a use-effectiveness study was undertaken by the Planned Parenthood Center of Buffalo New York involving 2000 oral contraceptive users between 1962 and 1968. Synthetic cohort life tables were compiled by various demographic characteristics using the Tietze procedure. Average age of the users was 24.9 years. 54.2% had an economic status of low-income and 36.3% a low-middle income. Continuations of use rate after one year was 82% after two years was 68% and dropped to 34% after 6 years. Women on combined oral contraceptives (66.6%) experienced significantly higher continuation rates and lower accidental pregnancy rates than women on sequential contraceptives. Younger women and those of lower parity appear to be at the greatest risk to oral contraceptive failure which is a similar finding for intrauterine device use-effectiveness. Physicians assuming high continuation rates for oral contraceptives should be made aware of these findings and a new contraceptive method for this high-risk group should be sought.

A four-year comparison between the utilization and use-effectiveness of sequential and combined oral contraceptives

A comparison of the utilization and effectiveness of the pill between comparable groups of women on sequential and combined doses was based on data gathered for 2,000 women from the Buffalo Planned Parenthood Center. The type of pill prescribed for women in this study was randomly selected. Synthetic cohort life tables, following procedures developed by Tietze, were compiled for women using each type of pill. The finding indicate that combined oral contraceptives are superior to sequentials. Not only was the rate of accidental pregnancy less than half as great for combined users, but the continuation rate was 14 percent higher for women on combined pills. In addition, significantly fewer women on combined pills terminated for medical reasons. These findings, combined with data from Sartwell, et al., which indicated that women on sequential pills are at higher risk to thromboembolism, provide persuasive evidence to limit the use of sequential contraceptives.

A FOUR-YEAR COMPARISON BETWEEN THE UTILIZATION AND USE-EFFECTIVENESS OF SEQUENTIAL AND COMBINED ORAL CONTRACEPTIVES

Abstract A comparison of the utilization and effectiveness of the pill between comparable groups of women on sequential and combined doses was based on data gathered for 2,000 women from the Buffalo Planned Parenthood Center. The type of pill prescribed for women in this study was randomly selected. Synthetic cohort life tables, following procedures developed by Tietze, were compiled for women using each type of pill. The finding indicate that combined oral contraceptives are superior to sequentials. Not only was the rate of accidental pregnancy less than half as great for combined users, but the continuation rate was 14 percent higher for women on combined pills. In addition, significantly fewer women on combined pills terminated for medical reasons. These findings, combined with data from Sartwell, et al. , which indicated that women on sequential pills are at higher risk to thromboembolism, provide persuasive evidence to limit the use of sequential contraceptives.