Effect of transport on blood selenium and glutathione status in feeder lambs.

Stress from transport may be linked to increased generation of reactive oxygen species, the removal of which requires reduced glutathione and selenium. The aim of this experiment was to examine the effect of transport on glutathione and Se status of feeder lambs. Recently weaned lambs (n = 40) were blocked by gender and BW on d 0 of the experiment and randomly assigned to 2 treatment groups: group 1, no transport and full access to feed and water (control), and group 2, 8-h road transport followed by another 16 h of feed deprivation (transport). After 24 h, both treatment groups were treated the same. All lambs were weighed, and blood samples were collected at 0, 8, 24, and 72 h and analyzed for whole-blood (WB) and serum Se concentrations, serum NEFA concentrations, and erythrocyte concentrations of glutathione. Transport of feeder lambs for 8 h followed by another 16 h of feed deprivation transiently (significant at 24 h but no longer different at 72 h) decreased BW and erythrocyte glutathione concentrations and increased serum NEFA and blood Se concentrations compared with control lambs. Our results suggest that 8 h of transport followed by another 16 h of feed deprivation results in fatty acid and Se mobilization from tissue stores with a coincident decrease in erythrocyte glutathione concentrations.

Organic and inorganic selenium: IV. passive transfer of immunoglobulin from ewe to lamb.

Newborn lambs depend on their dams for passive transfer of immunoglobulins, primarily IgG, for protection from harmful pathogens until their own immunological defenses have developed. Previous studies have suggested that supplementation with Se results in a modest increase in IgG concentration in serum of newborn calves and lambs. To evaluate the effect of the Se source and supplementation rate in ewes during pregnancy on passive transfer of IgG to their lambs, 210 Polypay, Suffolk, or Suffolk × Polypay cross ewes were divided into 7 treatment groups (n = 30 each) and drenched weekly with no Se, at the maximum FDA-allowed concentration with inorganic Na-selenite or organic Se-yeast (4.9 mg Se/wk), or with inorganic Na-selenite and organic Se-yeast at supranutritional concentrations (14.7 and 24.5 mg Se/wk). Ewe serum IgG concentrations were measured within 30 d of parturition, ewe colostrum and lamb serum IgG concentrations were measured at parturition before suckling, and lamb serum IgG concentrations were measured again at 48 h postnatal. Ewes receiving 24.5 mg Se/wk tended to have or had, independent of Se source, greater colostral IgG concentrations than ewes receiving 4.9 mg Se/wk overall (81.3 vs. 66.2 mg/mL; P = 0.08) and for Polypay ewes only (90.1 vs. 60.7 mg/mL; P = 0.03). Polypay ewes receiving Se-yeast at 24.5 mg Se/wk transferred a greater calculated total IgG amount to their lambs than Polypay ewes receiving Se-yeast at 4.9 mg Se/wk (15.5 vs. 11.6 g; P = 0.02), whereas the converse was true (interaction between Se source and dose concentration; P = 0.03) for Polypay ewes receiving inorganic Na-selenite at 24.5 mg Se/wk vs. Na-selenite at 4.9 mg/wk (11.6 vs. 15.7 g; P = 0.08). Our results suggest that supranutritional Se supplementation of Polypay ewes during pregnancy increases colostral IgG concentrations but that the optimal supplementation rate for IgG transfer from ewe to lamb may differ for Na-selenite and Se-yeast.

Organic and inorganic selenium: III. Ewe and progeny performance.

Selenium is an essential micronutrient in sheep, and deficiency can limit lamb growth and survival. To evaluate how different chemical forms of Se administered to mature ewes at comparative dosages affect ewe and progeny performance, 240 ewes were divided into 8 treatment groups (n = 30 each) and drenched weekly with no Se; at the maximum FDA-allowed concentration with inorganic Na-selenite or organic Se-yeast (4.9 mg Se/wk); with inorganic Na-selenate (8.95 mg Se/wk); or with inorganic Na-selenite and organic Se-yeast at supranutritional concentrations (14.7 and 24.5 mg Se/wk, respectively). The treatment period started approximately 2 wk before breeding and lasted for 62.5 wk. Ewes of the no-Se and Se-yeast groups continued treatments for another 21 to 24 wk through a second lambing season. Chemical form or dosage of Se did not affect ewe reproductive performance based on proportion of ewes lambing in each treatment group, or number of lambs born, nursed, or weaned per ewe (all P > 0.10). Ewes receiving the highest supplementation rate of Se-yeast at 24.5 mg Se/wk had higher BCS (scale 1 to 5) at the end of yr 1 (2.95 vs. 2.66; P = 0.05) than ewes receiving Se-yeast at 4.9 mg Se/wk. Performance was better in lambs from ewes receiving Se-yeast at 24.5 mg Se/wk than in lambs from ewes receiving Se-yeast at 4.9 mg Se/wk or no Se. In yr 1, lambs from ewes receiving Se-yeast at 24.5 vs. 4.9 mg Se/wk were heavier at 120 d of age (37.0 vs. 34.2 kg; P = 0.05). In yr 2, lambs from ewes receiving Se-yeast at 24.5 mg Se/wk were or tended to be heavier at 60 d of age than lambs from ewes receiving no Se (21.2 vs. 19.0 kg; P = 0.04) or lambs from ewes receiving Se-yeast at 4.9 mg Se/wk (19.2 kg; P = 0.09). This effect was more pronounced in ewes raising multiple lambs. We conclude that supranutritional supplementation of ewes with Se-yeast at 24.5 mg Se/wk improves lamb growth and ewe health without negatively affecting reproductive performance.

Organic and inorganic selenium: II. Transfer efficiency from ewes to lambs.

Adequate Se transfer from ewes to lambs is important to prevent Se-deficiency diseases. To evaluate how different chemical forms of Se administered at comparative dosages to mature ewes affect Se status of their lambs, 240 ewes were divided into 8 treatment groups (n = 30 each) and drenched weekly (at an amount equal to their summed daily intake) with no-Se (controls); at recommended amounts (4.9 mg of Se/wk) with inorganic Na-selenite, inorganic Na-selenate, or organic Se-yeast; or at supranutritional amounts (14.7 and 24.5 mg of Se/wk) with Na-selenite or Se-yeast for 1 yr. Weekly drenching of Se was effective at increasing (P < 0.002) Se concentrations in ewe colostrum and milk at 30 d of lactation and in improving (P < 0.001) the Se status of lambs (whole-blood and serum-Se concentrations at birth, and skeletal-muscle Se concentrations at 14 d of age). Selenium concentrations in lacteal secretions were greater in ewes drenched with Se-yeast (colostrum: 374, 436, and 982 ng/mL at 4.9, 14.7, and 24.5 mg of Se/wk, respectively; milk: 26, 39, 64 ng/mL) compared with ewes drenched with Na-selenite (colostrum: 204, 334, 428 ng/mL; milk: 16, 21, 24 ng/mL), and were also greater (P < 0.001) in their lambs. Selenium concentrations continued to increase (P < 0.001) in lamb whole blood (558 and 695 ng/mL at 14.7 and 24.5 mg of Se/wk, respectively), serum (126, 183 ng/mL), and skeletal muscle (991, 1,696 ng/mL) with supranutritional concentrations of Se-yeast, whereas Se concentrations did not differ in whole blood (304, 332 ng/mL), serum (77, 85 ng/mL), or skeletal muscle (442, 482 ng/mg) of lambs from ewes drenched with 14.7 or 24.5 mg of Se/wk of Na-selenite. We conclude that weekly oral drenching of ewes during gestation and lactation with organic Se-yeast results in a more efficient transfer of Se (over a wide range of supplementation rates) from ewe to lamb than does inorganic Na-selenite.

Organic and inorganic selenium: I. Oral bioavailability in ewes.

Although the essentiality of dietary Se for sheep has been known for decades, the chemical source and Se dosage for optimal health remain unclear. In the United States, the Food and Drug Administration (FDA) regulates Se supplementation, regardless of the source of Se, at 0.3 mg of Se/kg of diet (as fed), which is equivalent to 0.7 mg of Se/d or 4.9 mg of Se/wk per sheep. The objectives of this study were to evaluate the effects of Se source (inorganic vs. organic) and supplementation rate (FDA vs. supranutritional rates of 14.7 and 24.5 mg of Se/wk) on whole-blood (WB) and serum-Se concentrations. Mature ewes (n = 240) were randomly assigned to 8 treatment groups (n = 30 each) based on Se supplementation rate (4.9, 14.7, and 24.5 mg of Se•wk(-1)•sheep(-1)) and source [Na-selenite, Na-selenate (4.9 mg/wk only), and organic Se-yeast] with a no-Se control group (0 mg of Se/wk). Treatment groups were balanced for healthy and footrot-affected ewes. For 1 yr, ewes were individually dosed once weekly with 0, 4.9, 14.7, or 24.5 mg of Se, quantities equivalent to their summed daily supplementation rates. Serum- and WB-Se concentrations were measured every 3 mo in all ewes; additionally, WB-Se concentrations were measured once monthly in one-half of the ewes receiving 0 or 4.9 mg of Se/wk. Ewes receiving no Se showed a 78.8 and 58.8% decrease (P < 0.001) in WB- (250 to 53 ng/mL) and serum- (97 to 40 ng/mL) Se concentrations, respectively, over the duration of the study. Whole-blood Se decreased primarily during pregnancy (-57%; 258 to 111 ng/mL) and again during peak lactation (-44%; 109 to 61 ng/mL; P < 0.001). At 4.9 mg of Se/wk, Se-yeast (364 ng/mL, final Se concentration) was more effective than Na-selenite (269 ng/mL) at increasing WB-Se concentrations (P < 0.001). Supranutritional Se-yeast dosages increased WB-Se concentrations in a dose-dependent manner (563 ng/mL, 14.7 mg of Se/wk; 748 ng/mL, 24.5 mg of Se/wk; P < 0.001), whereas WB-Se concentrations were not different for the Na-selenite groups (350 ng/mL, 14.7 mg of Se/wk; 363 ng/mL, 24.5 mg of Se/wk) or the 4.9 mg of Se/wk Se-yeast group (364 ng/mL). In summary, the dose range whereby Se supplementation increased blood Se concentrations was more limited for inorganic Na-selenite than for organic Se-yeast. The smallest rate (FDA-recommended quantity) of organic Se supplementation was equally effective as supranutritional rates of Na-selenite supplementation in increasing WB-Se concentrations, demonstrating the greater oral bioavailability of organic Se.

Trends in pregnancy rates for the United States, 1976-97: an update.

OBJECTIVES: This report presents detailed pregnancy rates for 1996 and 1997 to update a recently published comprehensive report on pregnancies and pregnancy rates for U.S. women. METHODS: Tabular and graphic data on pregnancy rates by age, race, and Hispanic origin, and by marital status are presented and described. RESULTS: In 1997 an estimated 6.19 million pregnancies resulted in 3.88 million live births, 1.33 million induced abortions, and 0.98 million fetal losses. The 1997 pregnancy rate of 103.7 pregnancies per 1,000 women aged 15-44 years is the lowest recorded since 1976 (102.7), the first year for which a consistent series of national pregnancy rates is available. The 1997 rate was 10 percent lower than the peak rate in 1990 (115.6). The teenage pregnancy rate dropped steadily through 1997, falling to a record low of 94.3 pregnancies per 1,000 teenagers 15-19 years, 19 percent below the 1990 level (116.3). Rates for younger teenagers declined more than for older teenagers.

A history of the measurement of unintended pregnancies and births.

OBJECTIVES: This article reviews the history of the measurement of unwanted and unintended pregnancy in fertility surveys in the United States. These concepts were developed in order to help explain trends and differences in birth rates in the United States. BACKGROUND: Unwanted fertility was first measured systematically in a survey in Indianapolis in 1941. The first national surveys to measure the concept of unwanted fertility were the 1955 and 1960 Growth of American Families Studies. All three of these surveys were limited to married women. In the 1965 National Fertility Survey, the concept of mistimed births was introduced. The 1973, 1976, 1982, and 1988 National Survey of Family Growth (NSFG) continued to measure trends in unwanted and mistimed fertility, while expanding the population interviewed, from currently married to all marital statuses. The 1993 and 2001 NSFGs have enriched the data on wantedness with new measures of ambivalence and the strength of feelings about having children. CONCLUSION: Measures of unwanted fertility, while imperfect, have been useful and will continue to be improved in the future.

Trends in pregnancies and pregnancy rates by outcome: estimates for the United States, 1976-96.

OBJECTIVES: This report presents national estimates of pregnancies and pregnancy rates according to women's age, race, and Hispanic origin, and by marital status, race, and Hispanic origin. Data are presented for 1976-96. Data from the National Survey of Family Growth (NSFG) are used to show information on sexual activity, contraceptive practices, and infertility, as well as women's reports of pregnancy intentions. METHODS: Tables of pregnancy rates and the factors affecting pregnancy rates are presented and interpreted. Birth data are from the birth-registration system for all births registered in the United States and reported by State health departments to NCHS; abortion data are from The Alan Guttmacher Institute (AGI) and the National Center for Chronic Disease Prevention and Health Promotion, Centers for Disease Control and Prevention (CDC); and fetal loss data are from pregnancy history information collected in the NSFG. RESULTS: In 1996 an estimated 6.24 million pregnancies resulted in 3.89 million live births, 1.37 million induced abortions, and 0.98 million fetal losses. The pregnancy rate in 1996 was 104.7 pregnancies per 1,000 women aged 15-44 years, 9 percent lower than in 1990 (115.6), and the lowest recorded since 1976 (102.7). Since 1990 rates have dropped 8 percent for live births, 16 percent for induced abortions, and 4 percent for fetal losses. The teenage pregnancy rate has declined considerably in the 1990's, falling 15 percent from its 1991 high of 116.5 per 1,000 women aged 15-19 years to 98.7 in 1996. Among the factors accounting for this decline are decreased sexual activity, increases in condom use, and the adoption of the injectable and implant contraceptives.

Highlights of trends in pregnancies and pregnancy rates by outcome: estimates for the United States, 1976-96.

OBJECTIVES: This report presents key findings from a comprehensive report on pregnancies and pregnancy rates for U.S. women. The study incorporates birth, abortion, and fetal loss data to compile national estimates of pregnancy rates according to a variety of characteristics including age, race, Hispanic origin, and marital status. Summary data are presented for 1976-96. Data from the National Survey of Family Growth (NSFG) are used to show information on sexual activity and contraceptive practices, as well as women's reports of pregnancy intentions. METHODS: Tabular and graphic data on pregnancy rates by demographic characteristics are presented and interpreted. Birth data are from the birth registration system for all births registered in the United States and reported by State health departments to NCHS; abortion data are from The Alan Guttmacher Institute (AGI) and the National Center for Chronic Disease Prevention and Health Promotion, Centers for Disease Control and Prevention (CDC); and fetal loss data are from pregnancy history information collected in the NSFG. RESULTS: In 1996 an estimated 6.24 million pregnancies resulted in 3.89 million live births, 1.37 million induced abortions, and 0.98 million fetal losses. The pregnancy rate in 1996 was 104.7 pregnancies per 1,000 women aged 15-44 years, 9 percent lower than in 1990 (115.6), and the lowest recorded since 1976 (102.7). Since 1990 rates have dropped 8 percent for live births, 16 percent for induced abortions, and 4 percent for fetal losses. The teenage pregnancy rate has declined considerably in the 1990's, falling 15 percent from its 1991 high of 116.5 per 1,000 women aged 15-19 to 98.7 in 1996. Among the factors accounting for this decline are decreased sexual activity, increases in condom use, and the adoption of the injectable and implant contraceptives.

Options for measuring unintended pregnancy in cycle 6 of the National Survey of Family Growth.

PIP: The National Survey of Family Growth staff contracted with researchers for an improved measurement of unintended pregnancy for Cycle 6 in the year 2001. There is a need for additional data related to unintended pregnancy for individuals practicing contraception, and for individuals who wanted to be pregnant but are not using any method. Substantive additions for the study include motivation desire to avoid pregnancy, ambivalence, and reasons for unintended pregnancy. Moreover, the introduction at the beginning of the "intendedness" series is to know about the feelings of a woman right before she becomes pregnant. A question is asked on the method or methods used in the month of conception. The impact of the question on the respondents needs to be assessed.^ieng

Sample design, sampling weights, imputation, and variance estimation in the 1995 National Survey of Family Growth.

OBJECTIVES: Cycle 5 of the National Survey of Family Growth (NSFG) was conducted by the National Center for Health Statistics (NCHS) in 1995. The NSFG collects data on pregnancy, childbearing, and women's health from a national sample of women 15-44 years of age. This report describes how the sample was designed, shows response rates for various subgroups of women, describes how the sampling weights were computed to make national estimates possible, shows how missing data were imputed for a limited set of key variables, and describes the proper ways to estimate sampling errors from the NSFG. The report includes both nontechnical summaries for readers who need only general information and more technical detail for readers who need an in-depth understanding of these topics. METHODS: The 1995 NSFG was based on a national probability sample of women 15-44 years of age in the United States and was drawn from 14,000 households interviewed in the 1993 National Health Interview Survey (NHIS). Of the 13,795 women eligible for the NSFG, 10,847 (79 percent) gave complete interviews. RESULTS: This report recommends using weighted data for analysis and a software package that will estimate sampling errors from complex samples (for example, SUDAAN or comparable software). The rate of missing data in the 1995 NSFG was very low. However, missing data were imputed for 315 key variables, called "recodes." Of the 315 recodes defined for Cycle 5, 271 variables had missing data on less than 1 percent of the cases; only 44 had 1 percent or more with missing data. These missing values were imputed for all of these 315 variables. The imputation procedures are described in this report.

Trends in contraceptive use in the United States: 1982-1995.

CONTEXT: Trends in contraceptive use have implications for shifts in pregnancy rates and birthrates and can inform clinical practice of changes in needs for contraceptive methods and services. METHODS: Information on current contraceptive use was collected from a representative sample of women of reproductive age in the 1995 National Survey of Family Growth (NSFG). This information is compared with similar data from 1982 and 1988 to examine trends in use, both overall and in social and demographic subgroups. RESULTS: The proportion of U.S. women using a contraceptive method rose from 56% in 1982 to 60% in 1988 and 64% in 1995. As in 1982 and 1988, female sterilization, the pill and the male condom were the most widely used methods in 1995. Between 1988 and 1995, the proportion of users relying on the pill decreased from 31% to 27%, while condom use rose from 15% to 20%. The largest decreases in pill use and the largest increases in condom use occurred among never-married women and among black women younger than 25. Reliance on the IUD dropped sharply among Hispanic women, while use of the diaphragm fell among college-educated white women. CONCLUSIONS: The decline in pill and diaphragm use and the increase in reliance on condoms suggest that concerns about HIV and other sexually transmitted diseases are changing patterns of method use among unmarried women.

PIP: This article uses data from the 1982, 1988, and 1995 US National Surveys of Family Growth to describe the major contraceptive use trends between 1982 and 1995 as well as the subgroups responsible for important changes. The article focuses on current use of contraception by women of reproductive age, including sterilization and condom use, as defined by use of at least one method during the month of the interview. The proportion of women practicing contraception increased from 56% in 1982 to 60% in 1988 and 64% in 1995, with increases in all age, ethnic, and racial groups. Tables display the characteristics of women at risk of an unwanted pregnancy as well as the percentage distribution and number of contraceptive users 1) by current method; 2) by current method, race, and ethnicity; 3) of Whites and Blacks by current method according to age; 4) by age, marital status, education, income, and intent to have more children by method; 5) of White and Black users by method according to marital status and parity; 6) of White and Black users aged 20-44 by method according to education and income; and 7) the number of women aged 15-44 and percentage currently using specified contraceptive method combinations by age, marital status, education, income, parity, race/ethnicity, and number of male partners in the past year. The major finding was an increase in condom use, especially among young, Black, Hispanic, and unmarried women. This increase accompanied a decrease in use of oral contraceptives and the vaginal diaphragm. The data suggest the trends were affected by concerns about HIV/AIDS and sexually transmitted diseases and point the way to further research on contraceptive use trends.

Design and operation of the 1995 National Survey of Family Growth.

PIP: In the US, the 1995 National Survey of Family Growth (NSFG) was designed to provide richer data than previous NSFG surveys from 1973, 1976, 1982, and 1988. Planning for the 1995 NSFG took place at a series of meetings beginning in 1990. Pretesting of the expanded questionnaire, the new computer-assisted personal interviewing method, and the audio computer-assisted, self-interviewing method for sensitive topics occurred in 1993 and led to the decision to offer a cash incentive to respondents and to use the new interviewing methods. The revised questionnaire collected information on event histories, pregnancy history and family formation, partner history, sterilization and fecundity, contraception and birth expectations, use of family planning and other medical services, demographic characteristics, abortion history, number of sexual partners, and rape. The sample for the 1995 NSFG included 14,000 civilian, noninstitutionalized women of reproductive age, 13,795 of whom proved eligible. Of these, 79% completed interviews. Quality control measures included careful design and testing of the questionnaire, use of a Life History Calendar, intensive interviewer training, consistency checks, and use of the incentive. Sampling weights for each respondent were used to derive nationally representative statistical estimates. Sampling errors were created to reflect the complexity of the sample. Research based on the results of the 1995 NSFS has only begun to take advantage of the potential offered by these data.^ieng

Fertility, family planning, and women's health: new data from the 1995 National Survey of Family Growth.

OBJECTIVES: This report shows data on a wide range of topics from the 1995 National Survey of Family Growth (NSFG), including: pregnancy and birth, marriage, divorce, cohabitation, sexual intercourse, contraception, infertility, use of family planning and other medical services, and health conditions and behavior. METHODS: The data in this report are based on in-person interviews with a national sample of 10,847 women 15-44 years of age. The interviews lasted an average of 103 minutes. The response rate was 79 percent. The sample data are adjusted for nonresponse and are national estimates. RESULTS: Following large increases in the 1970's and 1980's, the proportion of teenagers who have ever had sexual intercourse decreased slightly between 1990 and 1995; condom use, both at first intercourse and currently, has increased markedly since the 1970's. These changes may have contributed to the decreases in the teen birth rate observed in the 1990's. For all women 15-44 years of age, the number whose partner was currently using the condom (at the date of interview) increased from 3.6 million in 1982 to 5.1 million in 1988 and 7.9 million in 1995. About 8 percent of women reported that their first intercourse was not voluntary. This result is consistent with an earlier national survey. About 20 percent reported that they had been forced by a man to have intercourse at some time in their lives. About 10 percent of births in 1990-95 were unwanted by the mother compared with 12 percent in 1984-88. The decrease in unwanted births was particularly large for black women. It appears that the prevalence of pelvic inflammatory disease (PID) and vaginal douching have both decreased since 1988.

Plan and operation of the 1995 National Survey of Family Growth.

OBJECTIVES: This report describes how the 1995 National Survey of Family Growth (NSFG) was designed, planned, and implemented. The NSFG is a national survey of women 15-44 years of age designed to provide national estimates of factors affecting pregnancy and birth rates and the health of women and infants. Planning for the 1995 NSFG began in 1990 at a formal conference with the survey's data users. Suggestions for substantial changes and improvements in the survey were made there and carried out by NSFG staff and the NSFG contractor--the Research Triangle Institute (RTI). METHODS: The survey was converted from paper and pencil interviewing to Computer-Assisted Personal Interviewing (CAPI) to improve the quality, consistency, and timeliness of the data. At the same time, event histories of the respondent's work, education, family background, cohabitation, and sexual partners were added to lend explanatory power to the survey. These changes made the interview and the CAPI program long--average interview length was 103 minutes--and complex, but the CAPI program worked very well. RESULTS: About 260 female interviewers were trained for 7 days in January 1995. These interviewers completed a total of 10,847 interviews with women 15-44 years of age, for a response rate of 79 percent. This report describes how the survey was planned and designed and how the data were collected, edited, and processed for public use. This report may be of interest to NSFG data users and to those planning other computer-assisted surveys.

Condom use for disease prevention among unmarried U.S. women.

Among a nationally representative sample of 932 sexually experienced unmarried women aged 17-44, 41% reported using condoms for protection against sexually transmitted diseases, and 30% said they used condoms for this reason every time or most times they had intercourse. While 67% of unmarried condom users cited disease prevention as their primary motivation for choosing this method, only 4% said contraception was their sole reason for using condoms; the remaining 29% gave both reasons. Condom use for disease prevention appeared most common among young women, never-married women, those with the highest incomes, women at an early stage of their reproductive career, women who had not been surgically sterilized and were not using oral contraceptives, those who believed in the effectiveness of condoms and women who had intercourse infrequently. Results of logistic regression analysis showed that black women and those who believed condoms and spermicides are effective in protecting against disease were about twice as likely as their counterparts to use condoms for disease prevention every time or most times they had sex; women who had intercourse two or more times a week, who used the pill or who had been pregnant were about half as likely as others to do so.

Understanding U.S. fertility: continuity and change in the National Survey of Family Growth, 1988-1995.

About 50 studies based on the 1988 National Survey of Family Growth (NSFG) and a telephone reinterview conducted with the same women two years later provide continuing information about the fertility and health of American women. Among the findings of these studies are that black women have almost twice as many pregnancies as do white women (5.1 vs. 2.8), with nearly all of the difference being unintended pregnancies. Unwanted births increased between 1982 and 1988, particularly among less-educated, poor and minority women. This increase in the proportion of unwanted births may have prompted the increase in female sterilization among these groups. Concern with the AIDS epidemic led to increases in condom use between 1982 and 1990, especially among the partners of teenagers and college-educated women. Rates of teenage pregnancy were fairly stable during the period 1980-1988, as increases in the proportion of teenagers having intercourse were offset by increases in condom use. Rates of infertility did not change significantly in the 1980s, but because of delayed childbearing and the aging of the baby-boom cohort, the number of older childless women increased substantially. The 1995 NSFG was redesigned in a number of ways in order to answer a new generation of questions about fertility and women's health in the United States.

PIP: US fertility surveys were conducted during 1955-70 and were formally instituted under the National Survey of Family Growth (NSFG) during 1973-88. Telephone reinterviews were conducted in 1990. This paper reviews findings from about 50 studies based on the NSFG in 1988 and 1990 and identifies changes in survey data and methods. Findings pertain to variables on intercourse and union formation, conception and contraceptive use, gestation, and fertility-related issues. Policy issues are discussed that relate to adolescent pregnancy, adoption, use of family planning services, maternal-child health, and HIV and sexually transmitted disease prevention. Cycle 5, which is scheduled for the NSFG in 1995, will be redesigned to accommodate policy needs. Changes will include increased coverage of explanatory patterns, such as family background, and inclusion of event histories for cohabitation and marriage, sexual partnerships, work, education, and past living arrangements with parents and grandparents. Measurement will improve for fertility-related variables that may explain unintended pregnancy. Such measures will cover consistency of contraceptive use, characteristics of sexual partners, women's attitudes about their pregnancies, family planning and infertility services, and other health care use measures. The 1995 survey will make a qualitative shift to computer-assisted personal interviewing. Abortion reporting will be more complete, due, in part, to the use of audio-assisted computer interviewing. Data collection occurred during January-October 1995. Trends during 1988-90 include higher rates of cohabitation, and large racial differences in the proportions who never married. There were increases in premarital sex behavior and in births to unmarried women. Perception of economic opportunity was associated with a greater likelihood of contraceptive use at first intercourse. Female sterilization was the leading method among women aged 30-34 years. First year failure rates were higher among low income women. Infertility and teenage pregnancy remained stable. Unintended fertility, which was strongly related to low education and income, older age, and Black race, was very high at 57% of all pregnancies.

Predictors of high-risk behavior in unmarried American women: adolescent environment as risk factor.

BACKGROUND: Heterosexual intercourse with two or more partners in a short time period represents a high-risk behavior for acquisition and transmission of sexually transmitted pathogens (STDs). Identification of factors that may predict high-risk sexual behavior can help to focus primary prevention strategies on women at risk for future acquisition of infection. METHODS: We analyzed survey data obtained in 1988 from a nationally representative sample of 8,450 American women of reproductive age in order to identify such factors. RESULTS: Of all sexually experienced unmarried women, 6.6% reported having had two or more sexual partners in the preceding three months. Earlier age at first sexual intercourse was associated with multiple recent partners, and with lower reports of abstinence. Birth region in the West, lack of attendance at religious services as an adolescent, and having a mother who had her first child before she was 25 years of age were factors associated with multiple recent partners. Among unmarried white women having a mother who worked full time and not living with both parents during adolescence were associated with multiple recent partners; among unmarried black women, the inverse was true (p for racial difference < .05). Multivariate analysis showed western birth region and earlier age at first sexual intercourse to be significant predictors of having multiple recent sex partners. CONCLUSIONS: Early environment and race influence later sexual behavior. These factors should be considered in targeting and planning education for STD prevention.

Use of infertility services in the United States.

OBJECTIVE: To examine the characteristics of women in the 1988 National Survey of Family Growth who reported having obtained medical services for impaired fecundity. METHODS: From a national sample of 8450 women between the ages of 15-44, drawn from the civilian, noninstitutionalized population of the entire United States in 1988, we estimated the use of infertility services in the United States. Multivariate statistical modeling was used to identify the characteristics associated with use of infertility services among the 770 women who reported impaired fecundity in this survey. RESULTS: Of all women with impaired fecundity, 43% had obtained some form of infertility service and 24% had obtained specialized infertility treatment--ovulation drugs, treatment of fallopian tubes, artificial insemination, or in vitro fertilization. Older, white, married women of higher socioeconomic status were most likely to have obtained specialized services, and a history of endometriosis was also strongly associated with having received such services. CONCLUSION: Most women with impaired fecundity had not obtained infertility services. Use of specialized services was strongly associated with certain sociodemographic variables or a history of endometriosis.