Según el artículo de Brady E. Hamilton, PhD. publicado en CDC (Center for Disease Control) en Mayo/2018 y divulgado en #OKILAB

Births: Provisional Data for 2017 

Brady E. Hamilton, Ph.D., Joyce A. Martin, M.P.H., Michelle J.K. Osterman, M.H.S., Anne K. Driscoll, Ph.D., and Lauren M. Rossen, Ph.D., Division of Vital Statistics, National Center for Health Statistics

Abstract Objectives—This report presents provisional 2017 data on U.S. births. Births are shown by age and race and Hispanic origin of mother. Data on prenatal care, cesarean delivery, preterm births, and low birthweight are also presented. This report is the second in a new annual series replacing the preliminary report series. Methods—Data are based on 99.93% of 2017 births. Records for the states with less than 100% of records received are weighted to independent control counts of all births received in state vital statistics offices in 2017. Comparisons are made with final 2016 data and earlier years. Results—The provisional number of births for the United States in 2017 was 3,853,472, down 2% from 2016 and the lowest number in 30 years. The general fertility rate was 60.2 births per 1,000 women aged 15–44, down 3% from 2016 and another record low for the United States. Birth rates declined for nearly all age groups of women under 40, but rose for women in their early 40s. The birth rate for teenagers aged 15–19 was down 7% in 2017 to 18.8 births per 1,000 women; rates declined for both younger (aged 15–17) and older (aged 18–19) teenagers. The cesarean delivery rate increased to 32.0% in 2017; the low-risk cesarean delivery rate increased to 26.0%. The preterm birth rate rose for the third year in a row to 9.93% in 2017; the 2017 rate of low birthweight (8.27%) was one of the highest levels reported since 2006. Keywords: birth rates • maternal and infant health • vital statistics

Introduction This report from the National Center for Health Statistics (NCHS) is part of the National Vital Statistics System Rapid Release, Quarterly Provisional Estimates data series. This series provides timely vital statistics for public health surveillance based on provisional data received and processed by NCHS as of a specified date. Estimates (quarterly and 12-month period ending with each quarter) for selected key vital statistics indicators are presented and released online through Quarterly Provisional Estimates. The series also includes reports that provide additional information on specific topics to help readers understand and interpret provisional natality and mortality data. Using provisional birth data for the 12 months of 2017 (1), this report supplements the Quarterly Provisional Estimates for 2017 by including topics not shown in the quarterly estimates (i.e., the timing of prenatal care and low birthweight rate) and also presenting more detail (by race and Hispanic origin of the mother and by state of residence) for selected topics than is shown in the quarterly estimates. This report is the second in a new annual series replacing the preliminary report series in order to provide a consistent set of quarterly and annual releases (2). Findings from this report will be compared with final birth data for 2017 to assess the accuracy of the estimates. Statistics in the provisional report for 2016 and preliminary reports for 1995–2015 have been shown to track well with the final statistics for the year (2,3). This report presents provisional data on births and birth rates and selected maternal and infant health characteristics for the United States in 2017.

Methods Findings are based on all birth records received and processed by NCHS for calendar year 2017 as of February 14, 2018; these records represent nearly 100% (99.93%) of registered births occurring in 2017. Comparisons in this report are based on the final data for 2016 and earlier years (3). Changes and differences presented in this report are statistically significant at the 0.05 level, unless noted otherwise. Starting in 2016, all 50 states, the District of Columbia, Puerto Rico, Guam, and Northern Marianas reported race data in accordance with the revised standards issued by the Office of Management and Budget in 1997. These standards allow for the reporting of a minimum of five race categories (American Indian or Alaska Native [AIAN], Asian, black or African American, Native Hawaiian or Other Pacific Islander [NHOPI], and white) either by single race (i.e., reported alone) or in combination (i.e., more than one race or multiple races) (4). The race and Hispanic-origin groups shown in this report follow the 1997 standards and differ from the bridged-race categories shown in reports based on race data prior to 2016 (5). The new categories are: non-Hispanic singlerace white, non-Hispanic single-race black, non-Hispanic single-race AIAN, non-Hispanic single-race Asian, non-Hispanic single-race NHOPI, and Hispanic. For brevity, text references to non-Hispanic white and non-Hispanic black women omit the term “single-race.” For further information on differences between single- and bridged-race groups, see references 2 and 3. Population estimates by age, sex, race, and Hispanic origin for 2017 were not available as of the preparation of this report. Accordingly, birth and fertility rates by race and Hispanic origin could not be shown (but numbers and percentages of births by race and Hispanic origin are shown). Rates by race and Hispanic origin and information on births to unmarried women (see Technical Notes) will be presented in the 2017 final birth report.

Results Births and birth rates Key findings, illustrated in Tables 1 and 2 and Figures 1 and 2, are listed below: ■ The provisional number of births for the United States in 2017 was 3,853,472, down 2% from the number in 2016 (3,945,875) (Table 1 and Figure 1). This is the third year that the number of births has declined after an increase in 2014, and the lowest number of births in 30 years (1987) (3,5,6). ■ Among the three largest race and Hispanic-origin groups, the provisional number of births declined 2% for Hispanic and 3% for non-Hispanic white women from 2016 to 2017; the number of births for non-Hispanic black women was essentially unchanged (Table 2) (3). The number of births declined 2% for non-Hispanic Asian and 5% for non-Hispanic AIAN women but was essentially unchanged for non-Hispanic NHOPI women. ■ The provisional general fertility rate (GFR) for the United States in 2017 was 60.2 births per 1,000 women aged 15–44, down 3% from the rate in 2016 (62.0), reaching another record low for the nation (Table 1 and Figure 1) (3,5,6). The decline in the rate from 2016 to 2017 was the largest singleyear decline since 2010 (3,5,6). ■ The provisional total fertility rate (TFR) for the United States in 2017 was 1,764.5 births per 1,000 women, down 3% from the rate in 2016 (1,820.5) and the lowest TFR since 1978 (3,5,6). The TFR estimates the number of births that a hypothetical group of 1,000 women would have over their lifetimes, based on the agespecific birth rates in a given year. The decline in the rate from 2016 to 2017 was the largest singleyear decline since 2010 (3,5,6). ■ The TFR in 2017 was again below replacement—the level at which a given generation can exactly replace itself (2,100 births per 1,000 women). The rate has generally been below replacement since 1971 (3,5,6). Maternal age ■ Provisional birth rates declined for women aged 15–39 from 2016 to 2017 but rose for women aged 40–44. ■ The provisional birth rate for teenagers in 2017 was 18.8 births per 1,000 women aged 15–19, down 7% from 2016 (20.3) and another record low for this age group (Table 1 and Figure 2) (3,5–7). The rate has declined by 55%, or nearly 8% per year, since 2007 (41.5), the most recent period of continued decline, and 70% (or 4% per year) since 1991, the most recent peak. The number of births to women aged 15–19 was 194,284 in 2017 (Table 1), down 7% from 2016 and down 56% from 2007 (444,899) (3,5–7). ■ The provisional birth rates for teenagers aged 15–17 and 18–19 in 2017 were 7.8 and 35.1 births per 1,000 women, respectively, down by 11% and 6% from 2016, again reaching record lows for both groups (3,5–7). ■ The provisional birth rate for females aged 10–14 was 0.2 births per 1,000 in 2017, which was unchanged since 2015. ■ The provisional birth rate for women aged 20–24 in 2017 was 71.0 births per 1,000 women, down 4% from 2016 (73.8), reaching another record low for this age group (Table 1 and Figure 2) (3,5,6). The number of births to women in their early 20s fell by 5% from 2016 (Table 1). ■ The provisional birth rate for women aged 25–29 was 97.9 births per 1,000 women, down 4% from 2016 (102.1) and another record low for this age group (3,5,6). The number of births to women in their late 20s fell 2% from 2016. ■ The provisional birth rate for women aged 30–34 in 2017 was 100.3 births per 1,000 women, down 2% from 2016 (102.7); this rate had risen steadily from 2012 to 2016 (Table 1 and Figure 2) (3,5,6). The number of births to women in their early 30s declined 2% from 2016. ■ The provisional birth rate for women aged 35–39 was 52.2 births per 1,000 women, down 1% from 2016 (52.7). The rate for this age group had risen each year from 2011 to 2016 (3,5,6). The number of births to women in their late 30s increased by 1% from 2016. ■ The provisional birth rate for women aged 40–44 in 2017 was 11.6 births per 1,000 women, up 2% from 2016 (11.4). The rate for this age group has generally risen since 1982 (3,5). The number of births to women in their early 40s increased by 1% from 2016. ■ The provisional birth rate for women aged 45–49 (which includes births to women aged 50 and over) was 0.9 births per 1,000 women, which was unchanged since 2015. The number of births to women in this age group rose 3% from 2016 to 2017 (Table 1). Maternal and infant health characteristics Key findings, illustrated in Tables 3–6 and Figures 3 and 4, are listed below: Prenatal care ■ The percentage of women receiving first trimester prenatal care in 2017 was 77.3%, up from 77.1% in 2016 (Table 3). The percentage of women receiving late (beginning in the third trimester) or no prenatal care remained unchanged at 6.2%. For prenatal care initiation by state, see Table 4. ■ The percentage of first trimester prenatal care ranged from 52.1% for non-Hispanic NHOPI women to 82.5% for non-Hispanic white women (Table 3). First trimester care increased for non-Hispanic white (82.3% to 82.5%), non-Hispanic Asian (80.6% to 81.1%), and Hispanic (72.0% to 72.3%) women from 2016 to 2017; there was essentially no change for non-Hispanic black, non-Hispanic AIAN, and non-Hispanic NHOPI women. ■ Late or no care ranged from 4.4% (non-Hispanic white women) to 20.3% (non-Hispanic NHOPI women) (Table 3). Late or no care increased from 2016 to 2017 for non-Hispanic white (4.3% to 4.4%) and non-Hispanic black (10.0% to 10.2%) women, decreased for non-Hispanic Asian women (5.4% to 5.1%), and remained essentially unchanged for non-Hispanic AIAN and non-Hispanic NHOPI women. Cesarean delivery ■ In 2017, the overall cesarean delivery rate increased to 32.0% (from 31.9% in 2016) (Tables 3 and 5). The rate had declined for 4 years in a row (2013–2016) after peaking in 2009 at 32.9% (3). See Table 5 for state-specific rates. ■ The cesarean delivery rate ranged from 28.5% of births for nonHispanic AIAN women to 36.0% for non-Hispanic black women (Table 3). Cesarean delivery among Hispanic women increased from 2016 (31.7%) to 2017 (31.8%); rates for non-Hispanic white, non-Hispanic black, non-Hispanic AIAN, non-Hispanic Asian, and non-Hispanic NHOPI women were essentially unchanged. ■ The low-risk cesarean delivery rate also increased in 2017 to 26.0% of births from 25.7% in 2016 (Figure 3). Low-risk cesarean is cesarean delivery among nulliparous (first birth), term (37 or more completed weeks based on the obstetric estimate), singleton (one fetus), vertex (head first) births. ■ Low-risk cesarean rates ranged from 22.8% for non-Hispanic AIAN women to 30.4% for non-Hispanic black women (Table 3). Low-risk cesarean rates increased from 2016 to 2017 for non-Hispanic white (24.7% to 24.9%), non-Hispanic AIAN (21.2% to 22.8%), and Hispanic (25.1% to 25.6%) women; rates for other groups remained essentially unchanged. Preterm birth ■ The preterm birth rate rose for the third year in a row to 9.93% in 2017, from 9.85% in 2016 (3) (Table 3). The percentage of infants born preterm (births at less than 37 completed weeks of gestation) fell 8% from 2007 (the first year for which national data are available based on the obstetric estimate of gestation) to 2014 but rose 4% from 2014 to 2017 (3). See Table 6 for state-specific rates. ■ All of the rise in the overall preterm rate from 2016 to 2017 is due to an increase in late preterm births (34–36 completed weeks of gestation) (Table 3), which rose from 7.09% of births to 7.17%. The percentage of infants born early preterm (less than 34 weeks) was unchanged from 2016 at 2.76%. ■ Preterm rates increased for births to non-Hispanic black (13.77% to 13.92%) and Hispanic (9.45% to 9.61%) women from 2016 to 2017; the rate was essentially unchanged among births to non-Hispanic white women (9.04% to 9.06%). Low birthweight ■ The low birthweight rate (LBW) also increased in 2017 for the third straight year to 8.27%, from 8.17% in 2016 (Table 3). The 2017 LBW rate (the percentage of infants born at less than 2,500 grams or 5 lb. 8 oz. per 100 births) is similar to the highest level ever reported (8.26% in 2006) (Figure 4) (8). Following a downward trend from 2007 through 2014, the LBW rate has risen 3% between 2015 and 2017. ■ The rate of moderately low birthweight (1,500–2,499 grams) rose from 6.77% of births in 2016 to 6.87% in 2017. The percentage of very low birthweight infants (less than 1,500 grams) was stable at 1.40% (Table 3) (3). ■ LBW rose among births to nonHispanic black (13.68% to 13.88%) and Hispanic (7.32% to 7.42%) women; the rate for births to Hispanic women was the highest reported since at least 1993 when national data became available for this group (5). The LBW rate was essentially unchanged from 2016 to 2017 among births to non-Hispanic white women (6.97% to 7.00%).