Circumstances of Women’s First Birth May Be Linked to Their Health During Middle Age
Once women reach late middle age, their mortality and disease risks may be related to their early childbearing history, according to analyses of data from the Health and Retirement Study (HRS), which conducts periodic surveys to track participants’ health, socioeconomic circumstances and family structure.1 Among U.S. women who were born in 1931–1941 and lived until at least the early 1990s, those who had first given birth as teenagers had elevated odds of dying between 1994 and 2002; they also were more likely than others to have had heart disease, lung disease or cancer by 1994. Women who had had a nonmarital first birth appeared to be at risk of early mortality, but the association lost significance when midlife socioeconomic status was taken into account.
HRS participants were first interviewed in 1992, when they were 51–61 years of age, and are reinterviewed every two years. The data set includes information on women before they gave birth, at the time of their first birth and during midlife. To assess the relationship between childbearing history and mortality in late middle age, the analyst examined data for 1994–2002, which were linked to national mortality statistics. Assessment of a variety of diseases was based on data from the 1994 survey.
In all, 4,335 women were included in the analyses. Most were U.S.-born and white; their average age was 56 at the time of the first survey, and they had had a mean of 12 years of schooling. In 1994, 69% of women were married, and most of the rest were divorced (13%) or widowed (12%). Also at that time, 41% of participants said that they had been told that they had high blood pressure, 10–13% had ever received a diagnosis of diabetes or heart or lung disease, 9% had had cancer and 3% had suffered a stroke. During the years for which mortality data were examined, 3% of women married, 9% became widows and 2% divorced.
Ninety-two percent of cohort members had had children; 83% had had more than one. One-quarter of parous women had first given birth as teenagers, and one in 10 had been unmarried at the time of their first birth. Four percent had given birth after age 39, and 36% had had a birth interval of less than two years. Parous women were generally similar to the overall cohort in terms of measures used in the analyses.
According to results of Cox regression analyses, women’s risk of dying between 1994 and 2002 rose significantly with increasing age and declined with increasing education, net worth and income; it was lower among women who were never-married in 1994 than among those who were married at the time. Results were essentially the same for parous women as for the cohort in general. In addition, parous women had an elevated mortality risk if they had given birth before their 20th birthday (hazard ratio, 1.6), and this relationship remained significant even after midlife socioeconomic circumstances were controlled for (1.4). In an initial regression, the risk of dying was elevated among women who had been unmarried at first birth (1.6); this association remained in analyses that adjusted for background characteristics that preceded first birth, but it lost significance in the final model, which added controls for midlife socioeconomic characteristics.
A series of logistic regression models controlling for background and midlife characteristics indicated that women who had given birth before age 20 were at increased risk of having had heart disease, lung disease or cancer by 1994 (coefficients, 0.3–0.4). Those who had had a nonmarital first birth were at increased risk for heart disease and stroke (0.4 and 0.6, respectively). Two reproductive history characteristics that were not significant predictors of mortality were associated with midlife health: The risk of heart disease was reduced among women who had given birth after age 39 (–0.6) and among those who had had a birth interval of less than two years (–0.3).
The analyst notes that the wide range of measures available from the HRS allows the most comprehensive examination ever of the relationships between childbearing history and later health and mortality. Nevertheless, he observes that three central questions remain: whether the association between early childbearing and mortality would be affected by the inclusion of additional background measures; whether the findings related to childbearing outside marriage would be the same for later cohorts, among whom nonmarital childbearing has been more common than it was for the HRS cohort; and how childbearing history is related to mortality throughout the life course. Studies on these issues, he concludes, would bring a greater understanding of the relationship between childbearing history and women’s later health.
1. Henretta JC, Early childbearing, marital status, and women’s health and mortality after age 50, Journal of Health and Social Behavior, 2007, 48(3):254–266.