Trends and Variations in Reproduction and Intrinsic Rates: United States, 1990-2014.

Objective-This report presents trends in reproduction and intrinsic rates from 1990 through 2014. In addition, total fertility and gross reproduction rates by race and Hispanic-origin group are presented from 1990 through 2014, and net reproduction and intrinsic rates for selected race and Hispanic-origin group are presented from 2006 through 2014. Methods-Tabular and graphic data on the trends in the reproduction and intrinsic rates for the United States, by race and Hispanic origin of mother, are presented and described. Results-Rates of reproduction (total fertility, gross reproduction, and net reproduction), the intrinsic rate of natural increase, and the intrinsic birth rate were lower in 2014 than 1990. After a steady decline from 1990 through 1997, all rates increased from 1997 through 2007 but declined again from 2007 through 2013. The rates increased between 2013 and 2014. Among the race and Hispanic subgroups examined, the total fertility and gross reproduction rates were lower for all groups in 2014 compared with 1990. The net reproduction rate, intrinsic rate of natural increase, and intrinsic birth rate for the selected groups non-Hispanic white, non-Hispanic black, and Hispanic declined from 2006 through 2014.

Prepregnancy Body Mass Index by Maternal Characteristics and State: Data From the Birth Certificate, 2014.

Objectives-This report describes prepregnancy body mass index (BMI) among women giving birth in 2014 for the 47-state and District of Columbia reporting areas that implemented the 2003 U.S. Standard Certificate of Live Birth by January 1, 2014.

Short Interpregnancy Intervals in 2014: Differences by Maternal Demographic Characteristics.

KEY FINDINGS: Data from the National Vital Statistics System •Nearly 29.0% of U.S. mothers who had a second or higher-order birth in 2014 had a short interpregnancy interval of less than 18 months. •Short intervals (i.e., less than 6 months, 6-11 months, and 12-17 months) were more common for mothers aged 35 and over (5.7%, 16.3%, and 22.1%, respectively) than mothers who were under age 20 at their previous birth (5.1%, 8.8%, and 8.4%). •Short intervals of less than 6 months and 6-11 months were more common among non-Hispanic black mothers (7.1% and 11.7%, respectively) than non-Hispanic white mothers (4.1% and 11.2%) and Hispanic mothers (5.0% and 9.3%). •The percentage of births to mothers with intervals less than 6 months decreased as education level increased, from 4.3% (no high school diploma) to 1.8% (doctorate or professional degree).

Interpregnancy Intervals in the United States: Data From the Birth Certificate and the National Survey of Family Growth.

OBJECTIVE: To describe data on interpregnancy intervals (IPI), defined as the timing between a live birth and conception of a subsequent live birth, from a subset of jurisdictions that adopted the 2003 revised birth certificate. Because this information is available among revised jurisdictions only, the national representativeness of IPI and related patterns to the entire United States were assessed using the 2006-2010 National Survey of Family Growth (NSFG). METHODS: Birth certificate data are based on 100% of births registered in 36 states and the District of Columbia that adopted the 2003 revised birth certificate in 2011 (83% of 2011 U.S. births). The "Date of last live birth" item on the birth certificate was used to calculate months between the birth occurring in 2011 and the previous birth. These data were compared with pregnancy data from a nationally representative sample of women from the 2006-2010 NSFG. RESULTS: Jurisdiction-specific median IPI ranged from 25 months (Idaho, Montana, North Dakota, South Dakota, Utah, and Wisconsin) to 32 months (California) using birth certificate data. Overall, the distribution of IPI from the birth certificate was similar to NSFG for IPI less than 18 months (30% and 29%), 18 to 59 months (50% and 52%), and 60 months or more (21% and 18%). Consistent patterns in IPI distribution by data source were seen by age at delivery, marital status, education, number of previous live births, and Hispanic origin and race, with the exception of differences in IPI of 60 months or more among non-Hispanic black women and women with a bachelor's degree or higher.

Measuring Gestational Age in Vital Statistics Data: Transitioning to the Obstetric Estimate.

Beginning with the 2014 data year, the National Center for Health Statistics is transitioning to a new standard for estimating the gestational age of a newborn. The new measure, the obstetric estimate of gestation at delivery (OE), replaces the measure based on the date of the last normal menses (LMP). This transition is being made because of increasing evidence of the greater validity of the OE compared with the LMP-based measure. This report describes the relationship between the two measures. Agreement between the two measures is shown for 2013. Comparisons between the two measures for single gestational weeks and selected gestational age categories for 2013, and trends in the two measures for 2007-2013 by gestational category, focusing on preterm births, are shown for the United States and by race and Hispanic origin and state.

Interpregnancy intervals in the United States: data from the birth certificate and the national survey of family growth.

To describe data on interpregnancy intervals (IPI), defined as the timing between a live birth and conception of a subsequent live birth, from a subset of jurisdictions that adopted the 2003 revised birth certificate. Because this information is available among revised jurisdictions only, the national representativeness of IPI and related patterns to the entire United States were assessed using the 2006-2010 National Survey of Family Growth (NSFG).

Newly released data from the revised U.S. birth certificate, 2011.

OBJECTIVES: This report is the first release of multistate data for selected items exclusive to the 2003 revision of the U.S. Standard Certificate of Live Birth. Included is information for prepregnancy body mass index, smoking and quitting smoking in the 3 months prior to pregnancy, receipt of food from the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) during pregnancy, pregnancy resulting from infertility treatment, source of payment for delivery, and maternal morbidities. METHODS: Descriptive statistics are presented for 100% of 2011 births to residents of the 36 states, the District of Columbia (D.C.), and Puerto Rico that had implemented the revised birth certificate by January 1, 2011. This reporting area is not a random sample, and results are not generalizable to the United States as a whole. RESULTS: The 3,267,934 births to residents of the 36-state and D.C. reporting area represented 83% of all 2011 U.S. births. Levels of prepregnancy obesity ranged from 18.0% in Utah to 28.6% in South Carolina. Hispanic women were the least likely to smoke in the 3 months prior to pregnancy and were the most likely to quit smoking prior to pregnancy. Women under age 20 were more than twice as likely to receive WIC food during pregnancy as women aged 35 and over in nearly all states and D.C. The percentage of births resulting from infertility treatment ranged from 0.3% in New Mexico to over 3.5% in Maryland and Utah. The percentage of deliveries covered by Medicaid ranged from 28.8% in North Dakota to 64.2% in Louisiana.

Annual summary of vital statistics: 2009.

The number of births in the United States decreased by 3% between 2008 and 2009 to 4 130 665 births. The general fertility rate also declined 3% to 66.7 per 1000 women. The teenage birth rate fell 6% to 39.1 per 1000. Birth rates also declined for women 20 to 39 years and for all 5-year groups, but the rate for women 40 to 44 years continued to rise. The percentage of all births to unmarried women increased to 41.0% in 2009, up from 40.6% in 2008. In 2009, 32.9% of all births occurred by cesarean delivery, continuing its rise. The 2009 preterm birth rate declined for the third year in a row to 12.18%. The low-birth-weight rate was unchanged in 2009 at 8.16%. Both twin and triplet and higher order birth rates increased. The infant mortality rate was 6.42 infant deaths per 1000 live births in 2009. The rate is significantly lower than the rate of 6.61 in 2008. Linked birth and infant death data from 2007 showed that non-Hispanic black infants continued to have much higher mortality rates than non-Hispanic white and Hispanic infants. Life expectancy at birth was 78.2 years in 2009. Crude death rates for children and adolescents aged 1 to 19 years decreased by 6.5% between 2008 and 2009. Unintentional injuries and homicide, the first and second leading causes of death jointly accounted for 48.6% of all deaths to children and adolescents in 2009.

Fetal and perinatal mortality, United States, 2006.

OBJECTIVES: This report presents 2006 fetal and perinatal mortality data by maternal age, marital status, race, Hispanic origin, and state of residence, as well as by fetal birthweight, gestational age, plurality, and sex. Trends in fetal and perinatal mortality are also examined. METHODS: Descriptive tabulations of data are presented and interpreted. RESULTS: There were 25,972 reported fetal deaths at 20 weeks of gestation or more in the United States in 2006. The U.S. fetal mortality rate was 6.05 fetal deaths at 20 weeks of gestation or more per 1,000 live births, 3% lower than in 2005 (6.22). From 2005 to 2006, fetal mortality declined 3% for fetal deaths at 20-27 weeks of gestation, while the rate at 28 weeks or more did not decline significantly. This contrasts with the long-term trend of declines in fetal mortality at 28 weeks or more and stability at 20-27 weeks of gestation. Fetal mortality rates declined significantly for non-Hispanic black women from 2005 to 2006; however, rates for other racial and ethnic groups were essentially unchanged. In 2006, the fetal mortality rate for non-Hispanic black women (10.73) was more than twice the rate for non-Hispanic white (4.81) and Asian or Pacific Islander (4.89) women. The rate for American Indian or Alaska Native women (6.04) was 26% higher, and the rate for Hispanic women (5.29) was 10% higher, than the rate for non-Hispanic white women. Fetal mortality rates were higher than average for teenagers, women aged 35 and over, unmarried women, and women with multiple pregnancies.

Childbearing differences among three generations of U.S. women.

Each year a generation of women is born who will share similar sociohistorical experiences before and throughout their reproductive lives. These unique experiences can produce similar childbearing patterns in terms of the average number of children ever born--whether mothers are younger or older when their first birth occurs and the proportion of women who do not have children--that can differ from the patterns found for other cohorts. Childbearing patterns have profound consequences for society. These consequences include the demand for schools and housing, as well as women's participation in the labor force. Moreover, the lives of women who become mothers are significantly different from those who do not. Having children affects the acquisition of material goods and may impose costs for the mother in terms of personal and professional options. This report presents data on three selected birth cohorts of women representing generations born at 25-year intervals in 1910, 1935, and 1960, close to the average length of a generation in the United States. Data are from the cohort fertility tables, based on the National Vital Statistics System.

Transitions between childlessness and first birth: three generations of U.S. women.

OBJECTIVE: This report analyzes the patterns of childlessness, and conversely, the first-birth patterns of three birth cohorts of American women. For this report, a cohort refers to women born in the same year. The cohorts compared were women born in 1910, 1935, and 1960-who, consequently, turned 25 during the Great Depression, the Baby Boom, and lastly, the post-Baby Boom period. The purpose of the report is to explore the differences in fertility characteristics of these three generations of women and to consider those differences in light of the social and economic conditions at the time. METHODS: Life table methodology, including the probability of having a first birth, the number of women remaining childless, and the expected number of years to remain childless, was applied to each of the three birth cohorts for comparison. Techniques extended from life table functions were also used and included measures of first-birth concentration as well as comparisons between childlessness and the total fertility rate (TFR). Data were based on the Centers for Disease Control and Prevention's National Center for Health Statistics tables on cohort fertility. RESULTS: Of the three birth cohorts studied, the women born in 1910 had the highest proportion childless and a low TFR. In contrast, the women born in 1935 had both the lowest proportion childless and the highest TFR. The fertility of women who were born in 1960 is characterized as intermediate to the other cohorts in terms of childlessness, but is distinct with both lowest levels of childbearing and oldest ages of first births. First-time childbearing is more concentrated (that is, least spread out) by age of mother for the 1910 and 1935 cohorts than the 1960 cohort. Finally, data for all U.S. birth cohorts 1910-1960 suggest that the greater the proportion childless in a cohort; the lower the TFR.

Births: final data for 2009.

OBJECTIVES: This report presents 2009 data on U.S. births according to a wide variety of characteristics. Data are presented for maternal characteristics including age, live-birth order, race and Hispanic origin, marital status, hypertension during pregnancy, attendant at birth, method of delivery, and infant characteristics (period of gestation, birthweight, and plurality). Birth and fertility rates by age, live-birth order, race and Hispanic origin, and marital status also are presented. Selected data by mother's state of residence are shown, as well as birth rates by age and race of father. Trends in fertility patterns and maternal and infant characteristics are described and interpreted. METHODS: Descriptive tabulations of data reported on the birth certificates of the 4.13 million births that occurred in 2009 are presented. Denominators for population-based rates are postcensal estimates derived from the U.S. 2000 census. RESULTS: The number of births declined to 4,130,665 in 2009, 3 percent less than in 2008. The general fertility rate declined 3 percent to 66.7 per 1,000 women aged 15-44 years. The teenage birth rate fell 6 percent to 39.1 per 1,000. Birth rates for women in each 5-year age group from 20 through 39 years declined, but the rate for women 40-44 years continued to rise. The total fertility rate (estimated number of births over a woman's lifetime) was down 4 percent to 2,007.0 per 1,000 women. The number and rate of births to unmarried women declined, whereas the percentage of nonmarital births increased slightly to 41.0. The cesarean delivery rate rose again, to 32.9 percent. The preterm birth rate declined to 12.18 percent; the low birthweight rate was stable at 8.16 percent. The twin birth rate increased to 33.2 per 1,000; the triplet and higher-order multiple birth rate rose 4 percent to 153.5 per 100,000.

Births: final data for 2007.

OBJECTIVES: This report presents 2007 data on U.S. births according to a wide variety of characteristics; preliminary 2008 data are also referenced on key measures where available. Final 2007 data are presented for maternal demographic characteristics including age, live-birth order, race and Hispanic origin, marital status, and educational attainment; maternal lifestyle and health characteristics (medical risk factors, weight gain, and tobacco use); medical care utilization by pregnant women (prenatal care, obstetric procedures, characteristics of labor and/or delivery, attendant at birth, and method of delivery); and infant characteristics (period of gestation, birthweight, Apgar score, congenital anomalies, and multiple births). Birth and fertility rates by age, live-birth order, race and Hispanic origin, and marital status also are presented. Selected data by mother's state of residence are shown, as well as data on month and day of birth, sex ratio, and age of father. Trends in fertility patterns and maternal and infant characteristics are described and interpreted. METHODS: Descriptive tabulations are presented of data reported on the birth certificates of the 4.3 million births that occurred in 2007. Preliminary 2008 data are based on 99.9 percent of births occurring in 2008. Denominators for population-based rates are postcensal estimates derived from the U.S. 2000 census. RESULTS: A total of 4,316,233 births were registered in the United States in 2007, the largest number of births ever reported. The general fertility rate increased 1 percent to 69.5 per 1,000. Birth rates increased for women in nearly all age groups. The rate for teenagers rose 1 percent for the year and is up 5 percent from 2005. The total fertility rate increased 1 percent to 2,122.0 births per 1,000 women. Preliminary data for 2008, however, suggest a decline in the number and rate of births overall, and for most age groups under age 40 years. All measures of unmarried childbearing reached record levels in 2007. The cesarean delivery rate rose to another all-time high--31.8 percent. Preterm and low birthweight rates declined slightly, and twin and triplet and higher-order multiple birth rates were essentially unchanged. Preliminary findings for 2008 suggest that these trends continued for cesarean delivery, unmarried childbearing, and preterm births.

Born a bit too early: recent trends in late preterm births.

KEY FINDINGS: The U.S. late preterm birth rate rose 20% from 1990 to 2006. If the late preterm rate had not risen from the 1990 level, more than 50,000 fewer infants would have been delivered late preterm in 2006. On average, more than 900 late preterm babies are born every day in the United States, or a total of one-third of 1 million infants (333,461). Increases in late preterm births are seen for mothers of all ages, and for non-Hispanic white and Hispanic mothers. The rate for black mothers declined during the 1990s, but has been on the rise since 2000. Late preterm birth rates rose for all U.S. states, but declined in the District of Columbia. The percentage of late preterm births for which labor was induced more than doubled from 1990 to 2006; the percentage of late preterm births delivered by cesarean also rose markedly.

The challenge of fetal mortality.

Data from the Fetal Death Data File and Linked Birth/Infant Death Data Set, National Vital Statistics System. The magnitude of fetal mortality is considerable: About 1 million fetal deaths occur at any gestational age in the United States each year, including almost 26,000 at 20 weeks of gestation or more; Even when limited to fetal deaths of 20 weeks of gestation or more, nearly as many fetal deaths as infant deaths occur in the United States each year; After decades of decline, the U.S. fetal mortality rate (fetal deaths of 20 weeks of gestation or more) did not decrease from 2003 to 2005; Fetal mortality rates are substantially higher for non-Hispanic black and American Indian or Alaska Native women than for non-Hispanic white women; Compared with the U.S. average, fetal mortality rates are higher for teenagers and for women aged 35 years and over, for twin and higher-order pregnancies, and for women with more than two previous pregnancies. Fetal mortality is a major, but often overlooked, public health problem. Fetal mortality refers to spontaneous intrauterine death at any time during pregnancy. Fetal deaths later in pregnancy are sometimes referred to as stillbirths (at 20 weeks of gestation or more, or 28 weeks or more, for example). Much of the public concern regarding reproductive loss has concentrated on infant mortality, as less is known about fetal mortality. However, the impact of fetal mortality on U.S. families is considerable.This report examines fetal death data from the National Vital Statistics System (NVSS). Vital statistics fetal death data are generally presented for fetal deaths of 20 weeks of gestation or more. Other data sources provide estimates of fetal deaths for all periods of gestation. For example, the National Survey of Family Growth estimates about 1 million fetal losses per year in the United States, with the vast majority of these occurring before 20 weeks of gestation.

Fetal and perinatal mortality, United States, 2005.

OBJECTIVES: This report presents 2005 fetal and perinatal mortality data by a variety of characteristics, including maternal age, marital status, race, Hispanic origin, and state of residence; and by fetal gestational age at delivery, birthweight, plurality, and sex. Trends in fetal and perinatal mortality are also examined. METHODS: Descriptive tabulations of data are presented and interpreted. RESULTS: In 2005, there were 25,894 reported fetal deaths of 20 weeks of gestation or more in the United States. The U.S. fetal mortality rate was 6.22 fetal deaths of 20 weeks of gestation or more per 1000 live births and fetal deaths, not significantly different from the rate of 6.20 in 2004 or 6.23 in 2003. The fetal mortality rate declined slowly but steadily from 1990 to 2003, but did not decline from 2003 to 2005. Most of the decline in the overall fetal mortality rate from 1990 to 2003 was due to a decline in fetal deaths of 28 weeks of gestation or more; fetal deaths of 20-27 weeks did not decline. From 2003 to 2005, fetal mortality rates did not decline for either gestational age grouping. From 2003 to 2005, fetal mortality rates declined significantly for non-Hispanic white and non-Hispanic black women, but not for Hispanic, American Indian or Alaska Native (AIAN), or Asian or Pacific Islander women. In 2005, the fetal mortality rate for non-Hispanic black women (11.13) was 2.3 times the rate for non-Hispanic white women (4.79). The rate for AIAN women (6.17) was 29% higher, and the rate for Hispanic women (5.44) was 14% higher than the rate for non-Hispanic white women. Fetal mortality rates are elevated for a number of groups, including teenagers, women aged 35 years and over, unmarried women, and multiple deliveries. In 2005, one-half of fetal deaths of 20 weeks of gestation or more occurred at 20-27 weeks of gestation.

Fetal and perinatal mortality, United States, 2004.

OBJECTIVES: This report presents 2004 fetal and perinatal mortality data by a variety of characteristics, including maternal age, marital status, race, Hispanic origin and state of residence; and by infant birthweight, gestational age, plurality and sex. Trends in fetal and perinatal mortality are also examined. METHODS: Descriptive tabulations of data are presented and interpreted. RESULTS: In 2004, there were 25,655 reported fetal deaths of 20 weeks of gestation or more in the United States. The U.S. fetal mortality rate was 6.20 fetal deaths of 20 weeks of gestation or more per 1,000 live births and fetal deaths, not significantly different from the rate of 6.23 in 2003. The fetal mortality rate for non-Hispanic black women (11.25) was 2.3 times the rate for non-Hispanic white women (4.98), whereas the rate for Hispanic women (5.43) was 9 percent higher than the rate for non-Hispanic white women. Fetal and perinatal mortality rates have declined slowly but steadily from 1990 to 2004. Fetal mortality rates for 28 weeks of gestation or more have declined substantially whereas those for 20-27 weeks of gestation have not declined. Fetal mortality rates are elevated for a number of groups, including teenagers, women aged 35 years and over, unmarried women, and multiple deliveries. In 2004, one-half of fetal deaths of 20 weeks of gestation or more occurred between 20 and 27 weeks of gestation.

Trends and differentials in higher-birthweight infants at 28-31 weeks of gestation, by race and Hispanic origin, United States, 1990-2002.

Birth certificate gestational age data based on the date of the mother's last menstrual period (LMP) are considered problematic. Of particular concern are birthweight distributions for infants reported on the birth certificate as having been delivered at 28-31 weeks' gestation; these distributions have been shown to be distinctly bimodal. The 'second curve' of the birthweight distribution at 28-31 weeks includes implausible birthweight/gestational age combinations and, thus, has been hypothesised to represent erroneous gestational ages due to misidentification of the date of LMP. It has been suggested that such 'misclassification' has declined in recent years and that this change can affect trends in preterm birth rates (<37 weeks' gestation), particularly rates among non-Hispanic black infants. This present study used primarily simple and multivariable analyses to review trends and differentials in birthweight distributions at 28-31 weeks by race and Hispanic origin of the mother. It aggregated data for the years 1990-92 and 2000-02 from the US vital statistics Natality files. Over the decade, the percentage of births in the second curve declined for all births and for each racial and Hispanic origin group studied. The largest decline was observed for non-Hispanic blacks; the smallest for Hispanic births. Later initiation of prenatal care, younger maternal age, lower educational attainment, higher birth order and vaginal and singleton delivery were positively associated with a larger second curve, suggesting misclassification of gestational age. Declines in the second curve over the study period were suggested to contribute significantly to the observed decrease in overall preterm birth rates for non-Hispanic black births. Further analysis is needed to estimate the influence of reporting error on preterm birth rates by race and Hispanic origin.

Births: final data for 2005.

OBJECTIVES: This report presents 2005 data on U.S. births according to a wide variety of characteristics. Data are presented for maternal demographic characteristics including age, live-birth order, race, Hispanic origin, marital status, and educational attainment; maternal lifestyle and health characteristics (medical risk factors, weight gain, and tobacco use); medical care utilization by pregnant women (prenatal care, obstetric procedures, characteristics of labor and/or delivery, attendant at birth, and method of delivery); and infant characteristics (period of gestation, birthweight, Apgar score, congenital anomalies, and multiple births). Also presented are birth and fertility rates by age, live-birth order, race, Hispanic origin, and marital status. Selected data by mother's state of residence are shown, as well as data on month and day of birth, sex ratio, and age of father. Trends in fertility patterns and maternal and infant characteristics are described and interpreted. METHODS: Descriptive tabulations of data reported on the birth certificates of the 4.1 million births that occurred in 2005 are presented. Denominators for population-based rates are postcensal estimates derived from the U.S. 2000 census. RESULTS: In 2005, 4,138,349 births were registered in the United States, 1 percent more than in 2004. The 2005 crude birth rate was 14.0, unchanged from the previous year; the general fertility rate increased slightly to 66.7. Teenage childbearing continued to decline, dropping to the lowest levels recorded. Rates for women aged 20-29 were fairly stable, whereas childbearing among women 30 years of age and older increased. All measures of unmarried childbearing rose substantially in 2005. Smoking during pregnancy continued to decline. No improvement was seen in the timely initiation of prenatal care. The cesarean delivery rate climbed to more than 30 percent of all births, another all-time high. Preterm and low birthweight rates also continued to rise; the twin birth rate was unchanged and the rate of triplet and higher order multiple births declined for the 7th consecutive year.

Births: final data for 2004.

OBJECTIVES: This report presents 2004 data on U.S. births according to a wide variety of characteristics. Data are presented for maternal demographic characteristics including age, live-birth order, race, Hispanic origin, marital status, and educational attainment; maternal lifestyle and health characteristics (medical risk factors, weight gain, and tobacco use); medical care utilization by pregnant women (prenatal care, obstetric procedures, characteristics of labor and/or delivery, attendant at birth, and method of delivery); and infant characteristics (period of gestation, birthweight, Apgar score, congenital anomalies, and multiple births). Also presented are birth and fertility rates by age, live-birth order, race, Hispanic origin, and marital status. Selected data by mother's state of residence are shown, as well as data on month and day of birth, sex ratio, and age of father. Trends in fertility patterns and maternal and infant characteristics are described and interpreted. METHODS: Descriptive tabulations of data reported on the birth certificates of the 4.1 million births that occurred in 2004 are presented. Denominators for population-based rates are post-censal estimates derived from the U.S. 2000 census. RESULTS: In 2004, 4,112,052 births were registered in the United States, less than 1 percent more than the number in 2003. The crude birth rate declined slightly; the general fertility rate increased by less than 1 percent. Childbearing among teenagers and women aged 20-24 years declined to record lows. Rates for women aged 25-34 and 45-49 years were unchanged, whereas rates for women aged 35-44 years increased. All measures of unmarried childbearing rose in 2004. Smoking during pregnancy continued to decline. No improvement was seen in the timely initiation of prenatal care. The cesarean delivery rate jumped 6 percent to another all-time high, whereas the rate of vaginal birth after previous cesarean fell by 13 percent. Preterm and low birthweight rates continued their steady rise. The twinning rate increased, but the rate of triplet and higher order multiple births was down slightly.