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Using data from the world fertility survey for Korea, repeatability of infant death in the family was investigated applying the log-linear model. There is a strong association in survivorship between any two consecutive births. No such association is observed in nonconsecutive birth orders. There is a suggestion however, that the survival of the first birth is related to that of the third or even the fourth birth order.
This report presents data on the numbers of teenage births and teenage birth rates for the United States for the period 1950-97 and State-specific birth rates for teenagers for 1991-96. After increasing sharply in the late 1980's, birth rates declined for American teenagers from 1991 through 1997. Rates fell overall by 16 percent for teenagers 15-17 years and by 11 percent for teenagers 18-19 years. Declines were reported for all race and ethnic origin groups, with the largest declines found for black teenagers, especially those aged 15-17 years. Particularly noteworthy has been the 21-percent decline in the rate of second births for teenagers who have had one child. Rates have fallen for first births as well, but the reductions are more modest, about 6 percent. Teenage mothers and their babies continue to be at greater risk of adverse health consequences compared with older mothers, including higher rates of preterm birth and low birthweight. While teenage birth rates vary considerably by State, rates fell in all States in the 1990's with nearly all declines statistically significant. Rates for black and non-Hispanic white teenagers dropped in most States from 1991 to 1996. Birth rate trends for Hispanic teenagers by State were not consistent. The proportion of second and higher order births among all teenage births declined substantially in most States. Data are from the National Center for Health Statistics' (NCHS) National Vital Statistics System.
OBJECTIVE: We sought to measure and compare pregnancy complications in middle school versus high school versus older maternal age groups. STUDY DESIGN: From January 1988 through December 31, 1991, maternal and infant data from 16,512 consecutive nulliparous women were collected and electronically stored. These women were divided into three study groups: middle school (11 to 15 years old), high school (16 to 19 years old), and women 20 to 22 years old at delivery. Statistical analysis included logistic regression to control for potentially confounding demographic variables. RESULTS: Middle school-aged mothers were disproportionately black (50% vs 36% Hispanic vs 14% white), and very low birth weight (4% vs. 2%, p = 0.003) was increased in these youthful mothers. First births to high school-aged mothers were not found to be compromised compared with those of women 20 to 22 years old, and, indeed, cesarean birth was less frequent in these women compared with those > or = 20 years old. CONCLUSIONS: We conclude that the health hazard associated with school-age pregnancy is predominantly prematurity and is increased only in middle school-aged mothers. High school-aged mothers do not experience excess medical complications of pregnancy compared with older women. We suggest that middle school pregnancy, particularly for inner-city teenagers, should be a special focus for pregnancy prevention and intervention.
To assess more precisely the relative risks associated with established risk factors for breast cancer, and whether the association between dietary fat and breast cancer risk varies according to levels of these risk factors, we pooled primary data from six prospective studies in North America and Western Europe in which individual estimates of dietary fat intake had been obtained by validated food-frequency questionnaires. Based on information from 322,647 women among whom 4,827 cases occurred during follow-up: the multivariate-adjusted risk of late menarche (age 15 years or more compared with under 12) was 0.72 (95 percent confidence interval [CI] = 0.62-0.82); of being postmenopausal was 0.82 (CI = 0.69-0.97); of high parity (three or more births compared with none) was 0.72 (CI = 0.61-0.86); of late age at first birth (over 30 years of age compared with 20 or under) was 1.46 (CI = 1.22-1.75); of benign breast disease was 1.53 (CI = 1.41-1.65); of maternal history of breast cancer was 1.38 (CI = 1.14-1.67); and history of a sister with breast cancer was 1.47 (CI = 1.27-1.70). Greater duration of schooling (more than high-school graduation compared with less than high-school graduation) was associated significantly with higher risk in age-adjusted analyses, but was attenuated after controlling for other risk factors. Total fat intake (adjusted for energy consumption) was not associated significantly with breast cancer risk in any strata of these non-dietary risk factors. We observed a marginally significant interaction between total fat intake and risk of breast cancer according to history of benign breast disease; with fat intake being associated nonsignificantly positively with risk among women with a previous history of benign breast disease; no other significant interactions were observed. Risks for reproductive factors were similar to those observed in case-control studies; relative risks for family history of breast cancer were lower. We found no clear evidence in any subgroups of a major relation between total energy-adjusted fat intake and breast cancer risk.
It has been hypothesized that breast cancer risk is influenced by prenatal hormone levels. Diethylstilbestrol (DES), a synthetic estrogen, was widely used by pregnant women in the 1950s and 1960s. Women who took the drug have an increased risk of breast cancer, but whether risk is also increased in the daughters who were exposed in utero is less clear. We assessed the relation of prenatal DES exposure to risk of breast cancer in a cohort of DES-exposed and unexposed women followed since the 1970s by mailed questionnaires. Eighty percent of both exposed and unexposed women completed the most recent questionnaire. Self-reports of breast cancer were confirmed by pathology reports. Cox proportional hazards regression was used to compute incidence rate ratios (IRR) for prenatal DES exposure relative to no exposure. During follow-up, 102 incident cases of invasive breast cancer occurred, with 76 among DES-exposed women (98,591 person-years) and 26 among unexposed women (35,046 person-years). The overall age-adjusted IRR was 1.40 [95% confidence interval (95% CI), 0.89-2.22]. For breast cancer occurring at ages >or=40 years, the IRR was 1.91 (95% CI, 1.09-3.33) and for cancers occurring at ages >or=50 years, it was 3.00 (95% CI, 1.01-8.98). Control for calendar year, parity, age at first birth, and other factors did not alter the results. These results, from the first prospective study on the subject, suggest that women with prenatal exposure to DES have an increased risk of breast cancer after age 40 years. The findings support the hypothesis that prenatal hormone levels influence breast cancer risk.
The directors of 269 neonatal intensive care units were surveyed to determine how low-birth-weight infants are being fed. Feeding practices were based on birth weight, with the smallest infants receiving parenteral nutrition for the longest time after birth. First enteral feedings usually were given by the nasogastric route in infants with birth weight of 1,500 g or less, but transpyloric feedings were used in 15% of neonatal intensive care units for infants with birth weight less than 1,000 g. The initial enteral feeding was sterile water in 56% to 58% of the neonatal intensive care units, but was glucose water or milk in the others. Once enteral feeding was established, both human milk from the infant's own mother and commercial formula were used. Whether human milk was mixed or alternated with infant formula, or whether some infants in the nursery were fed human milk while others were fed formula, was not determined. The type of infant formula fed to low-birth-weight infants depended on the infant's birth weight and clinical status. Both human milk and formula were supplemented with energy (fat or carbohydrates) and vitamins, but not with calcium and phosphorus, in most neonatal intensive care units. Some vitamins, such as vitamins A and D, may be oversupplemented, while others, such as folic acid, may be undersupplemented.
OBJECTIVE: To evaluate long-term pregnancy experiences of women exposed to diethylstilbestrol (DES) in utero compared with unexposed women. METHODS: This study was based on diethylstilbestrol-exposed daughters, the National Collaborative Diethylstylbistrol Adenosis cohort and the Chicago cohort, and their respective nonexposed comparison groups. Subjects who could be traced were sent a detailed questionnaire in 1994 that contained questions on health history, including information on pregnancies and their outcomes. We reviewed 3373 questionnaires from exposed daughters and 1036 questionnaires from unexposed women. RESULTS: The response rate was 88% among exposed and unexposed women. Diethylstilbestrol-exposed women were less likely than unexposed women to have had full-term live births and more likely to have had premature births, spontaneous pregnancy losses, or ectopic pregnancies. Full-term infants were delivered in the first pregnancies of 84.5% of unexposed women compared with 64. 1% of exposed women identified by record review (relative risk [RR] 0.76, confidence interval [CI] 0.72, 0.80). Preterm delivery of first births occurred in 4.1% of unexposed compared with 11.5% of exposed women, and ectopic pregnancies in 0.77% of unexposed compared with 4.2% of exposed women. Spontaneous abortion was reported in 19.2% of DES-exposed women compared with 10.3% in control women (RR 2.00, CI 1.54, 2.60). According to complete pregnancy histories (many women had more than one pregnancy), preterm births were more common in DES-exposed women (19.4% exposed versus 7.5% unexposed (RR 2.93 CI 2.23, 3.86). Second-trimester spontaneous pregnancy losses were more common in DES-exposed women (6.3% versus 1.6%; RR 4.25, CI 2.36, 7.66). More first-trimester spontaneous abortions occurred in DES-exposed women than in controls (RR 1.31, CI 1.13, 1.53), and DES-exposed women had at least one ectopic pregnancy more often than unexposed women (RR 3.84, CI 2.26, 6.54). CONCLUSION: Pregnancy outcomes in DES-exposed women were worse than those in unexposed women.
The purpose of this article is to describe the perinatal mortality experience and mortality-related risk factors of recent US multiple births. First, we describe trends in fetal and neonatal mortality rates for singleton and multiple births to understand if the improvements in perinatal mortality in the United States are equally or differentially reflected among multiple births. Because the characteristics of women who have multiple deliveries differ from those of mothers of singletons, we describe the risk of fetal and neonatal mortality by maternal characteristics and plurality. Finally, we examine the distribution and fetal and neonatal mortality risk of singleton and multiple births by birth weight and gestational age to provide an updated assessment and contrast of their comparative survival chances within similar birth weight-gestational age categories of intrauterine development.
The possible influence of induced abortion on breast cancer risk was assessed in a cohort of 267 040 women enrolled in a randomised trial of breast self-examination in Shanghai, China. Based on answers to a baseline questionnaire, subsequent breast cancer risk was not significantly associated with ever having an induced abortion. After adjustment for potential confounders, the relative risk estimate was 1.06 (95% C.I.: 0.91, 1.25), and there was no trend in risk with number of abortions. Analysis of data from more detailed interviews of 652 cases and 694 controls from the cohort yielded similar results. There was also no overall increase in risk in women with induced abortion after first birth. Few women had undergone an abortion after 13 weeks gestation or before their first child. Although increases in risk were observed in such women, they were not statistically significant and could have been due to recall bias. Abortions as they have been performed in China are not an important cause of breast cancer.
To understand possible correlates of the systematically higher gastric-cancer rates in males than in females, we investigated the role of menstrual, reproductive and hormonal factors in females, using data from a case-control study conducted in Northern Italy. Cases were 229 post-menopausal women with incident, histologically confirmed gastric cancer, and controls were 614 post-menopausal women in hospital for acute, non-neoplastic, non-digestive-tract conditions. After allowance for age, education, family history, and selected dietary correlates of stomach cancer, a reduced gastric-cancer risk was observed in women with later menopause (odds ratio, OR = 0.6, p value for trend < 0.05), and longer duration of fertile life (OR = 0.7, but the trend in risk was not significant). The risk of gastric cancer was elevated in multiparous women (OR = 1.7 for 3 and 1.9 for > or = 4 births as compared to nulliparae). No association was observed with age at menarche, age at first birth, and with number of spontaneous or induced abortions. Ever-users of oral contraceptives had a non-significant increased risk (OR = 1.3), and users of oestrogen-replacement treatment a non-significant reduced risk (OR = 0.5). Although the association with each factor was moderate, and the interpretation of these findings is not straightforward, these results are compatible with the hypothesis that some role is played by (endogenous and exogenous) female hormones in the process of gastric carcinogenesis.
BACKGROUND: The etiology of pancreatic cancer remains largely unknown. We examined the association of pancreatic cancer deaths with menstrual and reproductive factors in a cohort study involving Japanese women. METHODS: A total of 63,273 women were followed up for mortality from 1988 to 1999. Information on menstrual and reproductive factors was obtained by a questionnaire survey at baseline. Cox proportional-hazards models were used to estimate the relative risks (RRs) and 95% confidence intervals (CIs) for death from pancreatic cancer in relation to menstrual and reproductive factors. RESULTS: During 631,401 person-years of follow-up, 154 women died from pancreatic cancer. Parity was not significantly associated with the risk of death from pancreatic cancer; the RR was 0.80 (95% CI, 0.31-2.11) for women with six or more births compared with women with zero or one birth. We found no significant overall association with other reproductive factors, including pregnancy, age at first birth, and menopause. The risk appeared to increase with increasing age at menarche; the RR was 1.49 (95% CI, 0.95-2.34) for women who had menarche after 16 years of age compared to those who had menarche before they were 15 years old. CONCLUSIONS: Our prospective data indicate that menstrual and reproductive factors are not associated with the risk of death from pancreatic cancer among Japanese women.
BACKGROUND: There is evidence of a decline in semen quality in some countries, including Britain, in recent decades. This retrospective cohort study examined the hypothesis that biological fertility had also declined. The trend in couple fertility was assessed by means of time to pregnancy (TTP--a sensitive and validated measure of fertility. METHODS: A representative sample of the British population aged 16-59 years was surveyed. TTP was obtained for all births conceived after unprotected intercourse that began during 1961-93, excluding contraceptive failures. The sample size was 1540. FINDINGS: In contrast to the original hypothesis, this study found that fertility has increased; the rising trend was accompanied by slight dips during 1976-80 and 1986-90. These results were consistent between male and female respondents, and undiminished by adjustment for possible confounding factors. A stronger and more consistent relation was found with the year when unprotected intercourse started (a period effect) than with the year of birth of either partner (a birth cohort effect). INTERPRETATION: The findings could not be explained by trends in age at first birth, increased treatment of subfertility, or changes in oral contraceptive use. If a decline in male fertility has occurred, it has been more than compensated for by a countervailing increase in couple fertility.
Low birth weight has been linked at the aggregate level to unemployment rates and at the individual level to subjective distress. We hypothesize that maternal underemployment, including unemployment, involuntary part-time work, and low wage work predicts decreased birth weight. The relationship of birth weight to maternal employment changes during pregnancy was studied prospectively in 1,165 singleton first births in the National Longitudinal Survey of Youth data set. Controlling for other significant risk factors, women who shifted from adequate employment to underemployment had significantly lighter babies. Plausible mediators of this relationship were explored, including prenatal health care, gestational age, and mother's weight gain, with results varying by type of underemployment. Two interactions also suggested that underemployment reduced the beneficial effect of mother's weight gain on birth weight. These findings were partially replicated for low birth weight (< 2,500 grams), indicating the medical significance of the effect.
OBJECTIVE: Between 1987 and 1989 data were collected to evaluate risk factors for pelvic endometriosis. DESIGN: A case-control study was conducted on 241 cases with laparoscopically or laparotomically confirmed peritoneal or ovarian endometriosis consecutively admitted to three teaching hospitals in Northern Italy. The control group consisted of 437 women admitted to hospitals for acute conditions covering similar catchment areas. RESULTS: Compared with nulliparous women, the risk of endometriosis decreased with increasing number of births: the point estimates were 0.4 and 0.3, respectively, for those with one and two or more births (X2(1) trend = 50.3, P less than 0.001). No relation emerged with age at first birth and spontaneous miscarriages. Relative to women whose menarche occurred at age 11 or younger, the risk of endometriosis was slightly lower in those who experienced later menarche, but the trend in risk was not significant. Women with irregular menstrual cycles showed a lower frequency of the disease (relative risk, 0.3; 95% confidence interval, 0.2 to 0.5). The role of various factors was largely similar for different disease locations (ovary, peritoneum, and both) and indication for diagnostic surgery (sterility, pelvic pain, and other reasons). CONCLUSIONS: This study found that parity and irregular/long menses lower the risk of endometriosis. These findings were similar in different subgroups of disease location and indication for surgery, giving strong evidence of the consistency of the general results.
OBJECTIVE: To report the first birth after transfer of cryopreserved embryos generated by intracytoplasmic sperm injection of cryopreserved testicular spermatozoa into cryopreserved human oocytes. DESIGN: Case report. SETTING: Tertiary center for reproductive technology. PATIENT(S): A 36-year-old woman with primary infertility of 3 years' duration and a 37-year-old man with congenital bilateral absence of the vas deferens. INTERVENTION(S): Cryopreservation of human embryos after oocytes and sperm thawing. MAIN OUTCOME MEASURE(S): Live birth. RESULT(S): A healthy, normal female infant with a birth weight of 2,950 g was born by cesarean section at 38 weeks' gestation, with normal 6-month follow-up. CONCLUSION(S): Embryo cryopreservation can lead to successful results, even with the use of cryopreserved gametes.
Although certain risk factors for breast cancer incidence may also effect survival, findings have been inconsistent and the long-term role of childbirth is unknown. We studied the influence of number and timing of births on breast cancer prognosis prospectively. From 1958 to 1997, altogether 32,003 women, born 1932 or later, were notified to the Swedish Cancer Registry due to a primary invasive breast cancer. We obtained information on dates of all childbirths and achieved complete follow-up through 1997 by means of linkage to other nation-wide databases. Proportional hazards analyses were used to compute crude and multivariate hazard ratios (HR) with 95% confidence intervals (CI) of dying from breast cancer. We found a successively worse prognosis for women with a shorter delay between their last birth and breast cancer diagnosis (p for trend <0.0001). Compared to women with their last birth more than 10 years before diagnosis, the multivariate HR of breast cancer death was 1.39 (95% CI 1.17-1.67) for those with breast cancer diagnosis in the 3rd year after last birth and 1.72 (CI 95% 1.42-2.09) for those with diagnosis within 1 year after last birth. This adverse effect on prognosis of childbirth persisted beyond 10 years among women with a first birth before the age of 20 years. A pregnancy has marked adverse effects on the prognosis of a breast cancer diagnosed within 10 years after delivery. These findings suggest that pregnancy influences tumor biology.
OBJECTIVE: To evaluate risk disparities and risk factors for infant mortality among adolescent childbearing age groups. METHODS: We combined the 1995 and 1996 comprehensive U.S. birth cohorts provided by the National Center for Heath Statistics. Our analysis included 777,762 singleton, first births to women aged 12-19 years linked to 4631 infant deaths. We used both bivariate comparisons and multivariable logistic regression for our analysis, with infant mortality as our main outcome measure. RESULTS: Rates of infant mortality are substantially higher for < or =15-year-olds (8.1/1000 live births) compared with 16-17-year-olds (6.3/1000 live births) and 18-19-year-olds (5.4/1000 live births). Even after adjusting for risk factors associated with poor outcomes, including alcohol use, tobacco use, and prenatal care use, the risk for infant mortality was 1.6 (95% confidence interval [95% CI] 1.4, 1.7) times greater for infants of mothers < or =15 years old as compared with those mothers 18-19 years old. In the < or =15-year-old group, 62% of fathers were not reported on the child's birth certificate. Not reporting the father was associated with a 24% increased risk for infant mortality after adjusting for maternal and infant risk factors. CONCLUSIONS: Childbearing in < or =15-year-olds is associated with a substantial increased risk for infant mortality compared with childbearing in older adolescence. This study suggests that not reporting the father on a birth certificate is a potential risk marker. Risk differences among adolescent age groups may be important to consider when creating tailored intervention and prevention strategies.
In many countries, the male:female ratio at birth has varied significantly over the past century, but the reasons for these changes have been unclear. The authors observed a close parallel between decreasing family size and declining male:female sex ratio in Denmark from 1960 to 1994. To explain this finding, they examined the sex ratio and birth order of 1,403,021 children born to 700,030 couples. Overall, 51.2% of the first births were male. However, families with boys were significantly more likely than expected to have another boy (biologic heterogeneity). By the fourth birth to families with three prior boys, 52.4% were male. The increase varied directly with the number of prior boys (p for trend = 0.0007). Furthermore, couples with boys were more likely to continue to have children. In summary, the authors found that the declining male:female ratio in Denmark and probably other European populations is mainly attributable to three effects: declining family size, biologic heterogeneity, and child sex preference. Why families with boys are more likely to have additional boys is unknown.