Source: National Vital Statistics System, 2018
Source: National Vital Statistics System, 2018
Questions for Joyce Martin, Health Statistician and Lead Author of “Births: Final Data for 2018”
Q: What is new in this report from the 2018 provisional birth report?
JM: In addition to providing final numbers and rates for numerous birth characteristics such as fertility rates, teen childbearing, cesarean delivery and preterm and low birthweight, this report presents final information on teen childbearing by race and Hispanic origin and by state, births to unmarried women, tobacco use during pregnancy, source of payment for the delivery and twin and triplet childbearing.
Q: Was there a specific finding in the 2018 final birth data that surprised you?
JM: The continued decline in birth rates to unmarried women (down 2% for 2017-2018 to 40.1 births per 1,000 unmarried women), the fairly steep decline in tobacco smoking among pregnant women (down 6% to 6.5% of all women) and the continued declines in twin (down 2%) and triplet (down 8%) birth rates. Also of note is the decline in the percentage of births covered by Medicaid between 2017 and 2018 (down 2% to 42.3%) and the small rise in the percentage covered by private insurance (49.6% in 2018).
Q: How did you obtain this data for this report?
JM: These data are based on information for all birth certificates registered in the United States for 2018.
Q: What is the take home message for this report?
JM: Birth certificate data provide a wealth of important current and trend information on demographic and maternal and infant health characteristics for the United States.
Q: Why do you think the birth has dropped in the U.S.?
JM: The factors associated with family formation and childbearing are numerous and complex, involving psychological, cultural, demographic, and socio-economic influences. The data on which the report is based come from all birth certificates registered in the U.S. While the data provide a wealth of information on topics such as the number of births occurring in small areas, to small population groups, and for rare health outcomes, the data do not provide information on the attitudes and behavior of the parents regarding family formation and childbearing. Accordingly, the data in and of itself cannot answer the question of why births have dropped in the U.S.
Questions for Joyce Martin, Lead Author of, “Is Twin Childbearing on the Decline? Twin births in the United States, 2014-2018.”
Q: Is this the first time you have published a report on this topic?
JM: General information on twin births is published annually in the National Vital Statistics Report series “Births: Final Data.” A number of special reports have also been published on the topic in the past.
Q: Why did you decide to do a report on trends in twin births?
JM: There appears to be a reversal in the direction of trends in twin childbearing in the US. After increasing for decades, the number and rate of twin births trended downward for 2014-2018. This is important to public health because of the greater risk of poor pregnancy outcome, such as preterm birth and infant death, for babies born in twin pregnancies compared with those born in single pregnancies.
Q: How did the data vary by maternal age, race and Hispanic origin and state of residence?
JM: Trends differed by all of these characteristics. Rates for women in their 30s and over declined by 10%-12% and rates for women 40 and over by more than 20%. In contrast, there was no significant change in trends for women in their twenties. Among the three race/Hispanic origin groups studied, twin childbearing declined for 2014-2018 among non-Hispanic white women but were essentially unchanged among non-Hispanic black and Hispanic women. Rates declined significantly in 17 states and increased in only three states.
Q: Was there a specific finding in your report that surprised you?
JM: The steady decline in twinning from 2014 through 2018 after many years of increases was surprising as was the fairly large declines among women aged 30 and over.
Q: Do you foresee the decline in twins continuing?
JM: As fertility procedures continue to improve, twin births, and especially higher-order multiple births, would be expected to continue to decline. However, it is important to note that older mothers, those aged 35 and over, are more likely to have a twin delivery without the use of fertility therapies. The older age of women at birth may also affect twining rates.
Questions for Brady E. Hamilton, Ph.D., Demographer, Statistician, and Lead Author of “Educational Attainment of Mothers Aged 25 Years and Over: United States, 2017.”
Q: Why study education attainment of mothers in the United States?
BH: Educational attainment of the mother is considered an important measure of socioeconomic status. Maternal education has been shown to be associated with the number of births per woman, timing of childbearing, contraceptive use, and risk of adverse birth outcomes. Women with higher educational attainment have been shown to be more likely to desire and give birth to fewer children and are less likely to engage in behaviors detrimental to their health and pregnancy.
Q: How did you obtain data on educational attainment of mothers?
BH: Information on the educational attainment of mother shown in the report is based on data from 100% of the birth certificates filed in the states and District of Columbia in 2017. The birth certificate includes a question on the highest degree or level of school completed by the mother at the time of delivery. Data collected from the birth certificates on this and other items are provided to the National Center for Health Statistics.
Q: How did educational attainment of mother vary by race and state in 2017?
BH: Large differences in maternal educational attainment are observed by race and Hispanic origin and by state. For example, for mothers aged 25 and over with a Bachelor’s or advanced degree in 2017, levels ranged from a low of 12.7% and 13.2% for non-Hispanic American Indian or Alaska Native and Native Hawaiian or Other Pacific Islander mothers to a high of 67.9% for non-Hispanic Asian mothers. By state, the percentage of births to mothers aged 25 and over with a Bachelor’s or advanced degree ranged from a low of 26.6% for Nevada to a high of 58.5% for the District of Columbia.
Q: Do you have trend data on educational attainment of mothers that goes back 10 or 20 years?
BH: No, this report is the first to present information on the educational attainment of mothers in the United States in more than 20 years. During this time, comparable data on the education level of mothers were not available for all of the states and District of Columbia and so national data could not be produced. Comparable national data on the education level became available only recently, in 2016. The last report to present national data on the educational attainment was published in 1997 (https://www.cdc.gov/nchs/data/mvsr/supp/mv45_10s.pdf .
Q: Was there a specific finding in your report that surprised you?
BH: The range in the mean number of live births by level of educational attainment is certainly noteworthy. The difference in the mean between women with less than a 12th grade education with no diploma and women with an advanced degree is nearly 1 whole birth. In addition, the wide range in the percentage of births by educational attainment for the race and Hispanic origin groups and state, mentioned above, were also notable.
The comprehensive report on final births data for the United States was released on November 7, 2018, documenting a total of 3,855,500 births registered in the United States, down 2% from 2016. Compared with rates in 2016, the general fertility rate declined to 60.3 births per 1,000 women aged 15–44. The birth rate for females aged 15–19 fell 7% in 2017. Birth rates declined for women in their 20s and 30s but increased for women in their early 40s. The total fertility rate declined to 1,765.5 births per 1,000 women in 2017. Birth rates for both married and unmarried women declined from 2016 to 2017, and the percentage of babies born to unmarried women (39.8) did not change between 2016 and 2017. Many of these findings were documented in a May 2018 provisional release of 2017 data.
The final data are contained in the new publication “Births: Final Data for 2017.”
Some new data for 2017 are included for the first time in the new report:
Questions for Brady E. Hamilton, Ph.D., Demographer, Statistician, and Lead Author of “Births: Provisional Data for 2017”
Q: What did you think was the most interesting finding in your new analysis?
BH: The report includes a number of very interesting findings. The general fertility rate, 60.2 births per 1,000 women aged 15–44, declining 3% in 2017 and reaching a record low is certainly noteworthy. In addition, the continued decline in the birth rate for teens, down 7% from 2016 to in 2017, and reaching another record low, is very significant. The increase in the cesarean delivery rate following several years of decline is noteworthy as are the recent increase in rates of preterm and low birthweight births.
Q: Why does fertility keep going down in the U.S.?
BH: In general, there are a number of factors associated with fertility. The data on which the report is based comes from the birth certificates registered for births in the U.S. While the scope of this data is essentially all births in the country, and provides detailed information about rare events, small areas, or small population groups, the data does not provide information about the parent’s decision to have (or not have) a child. And so, accordingly, we cannot examine the “why” of the changes and trends in births.
Q: Does the decline in the Total Fertility Rate essentially mean fertility is down below “replacement” levels? Could you explain this in general terms?
BH: “Replacement” refers to a minimum rate of reproduction necessary for generation to exactly replace itself, that is, enough children born to replace a group of 1,000 women and their partners. For the total fertility rate, this rate is generally considered to be 2,100 births per 1,000 women. In 2017, the total fertility rate, 1,764.5 births per 1,000 women, was below replacement.
Q: Do the increases among women over 40 suggest a “new norm” in people waiting till much later to have children?
BH: Birth rates for women aged 40-44 and 45-49 years have increased generally over the last 3 decades. Given this, it reasonable to expect this trend to continue.
Q: Are the annual declines in teen pregnancy something that we are in danger of taking for granted?
BH: The birth rate for females aged 15-19 has decreased 8% per year from 2007 through 2017. For comparison, the decline in the birth rates for women aged 20-24 and 25-29 was 4% and 2% from 2007 through 2017. The decline in teen births is very noteworthy.
Q: Can you explain how the increases in preterm births and low birthweight are connected?
BH: Infants born preterm are also often, but not exclusively, born low birthweight and vice-versa. The causes of the recent upward shift in these rates are not well understood.
Source: National Vital Statistics Reports, Volume 67, Nos. 1 and 2
Questions for Anne K. Driscoll, Ph.D., Statistician and Lead Author of “Asian American Mothers: Maternal Characteristics by Maternal Place of Birth and Asian Subgroup, United States, 2016”
Q: What do you feel was the most interesting finding in your report?
AD: Although Asian mothers as a groups differ from other mothers on the characteristics analyzed, they are a heterogeneous group; birthplace and Asian subgroup are key sources of that heterogeneity.
Q: What countries of origin do Asian-Indian mothers come from?
AD: Asian Indian refers to people from India (i.e., to distinguish between people from India and Native Americans/ American Indians).
Q: How do we explain the significant difference between unmarried childbearing among Asian women vs. the rest of the U.S.?
AD: It is likely that the difference is related to differences in educational attainment and maternal age between Asian women and other women, as well as to other factors not measured here.
Q: How do the high education levels among Asian mothers compare to U.S. mothers of other races?
AD: Asian mothers have the highest education levels of any race/Hispanic origin group; the percent with at least a bachelor’s degree is roughly 50% higher than that of non-Hispanic white mothers, the group with the second highest education level.
Q: Any other significant findings you’d like to mention about your study?
AD: Asian mothers, both those born in and outside the US, were more likely to be age 30 and over and less likely to be teen mothers than other groups.
Questions for Joyce A. Martin, M.P.H., Demographer, Statistician, and Lead Author on “Births: Final Data for 2015”
Q: Was there a result in your study’s analysis of births in the United States that you hadn’t expected and that really surprised you?
JM: Although small, (from 9.57% to 9.63%) the rise in the preterm birth rate (births of less than 37 completed weeks of gestation) was unexpected. This rate had been declining steadily since 2007.
Also of note is the decline in the triplet and higher-order multiple birth rate, down 9% from 2014 to 2015, and a decrease of 46% since 1998. The year 2015 also is the third straight year of declines in the rate of cesarean delivery (rate of 32.0% in 2015).
The continued, large decline in the teen birth rate (down 8% from 2014 to 2015) was also somewhat surprising, although not unprecedented. From 2007 through 2014, the teen birth rates had declined 7% annually.
Q: What is the difference between this new births report and the other reports your office produced on 2015 birth data, like the preliminary data report on 2015 births and the Data Brief on teen births?
JM: The annual report “Births: Final Data for 2015” offers substantially more detail (e.g., age, race and Hispanic origin of mother, state) on key topics, than does the report on preliminary birth statistics (“Births: Preliminary Data for 2015”). The final report also includes information on topics not included in the preliminary reports such as multiple births, attendant and place of birth, birth order and birth rates for fathers.
Q: How has the number of births in the United States changed in 2015 from previous years?
JM: The number of births in the United States declined slightly in 2015 (by 9,579 births to 3,978,497) from 2014. The decline for 2015 followed an increase in births for 2014, which was the first increase since 2007.
Q: What differences, if any, did you see among race and ethnic groups, and among various ages?
JM: Of continued concern are the higher risks of poor birth outcomes as measured by levels of preterm birth and low birthweight among non-Hispanic black mothers compared with total births and other race and Hispanic origin groups. For example, in 2015 the preterm birth rate for births to non-Hispanic black mothers was more than 50% higher at 13.41% than for non-Hispanic white women (8.88%) and nearly 50% higher than the rate for births to Hispanic mothers (9.14%).
Q: Did you observe any regional or state differences in this study on births?
JM: Differences by state were observed for many of the demographic and medical/health items included in the 2015 final birth report. For example, from 2014 to 2015, the general fertility rate–which is the number of births per 1,000 women aged 15–44–declined in eight states and was essentially unchanged in the 42 states and the District of Columbia (DC). In 2015, the general fertility rate ranged among states from 51.1 births per 1,000 women aged 15–44 in Vermont to 78.2 in South Dakota.
Also, increases in preterm birth rates were limited to four states from 2014 to 2015: Arkansas, California, Nebraska, and North Carolina. Rates declined in four states: Montana, New York, Texas and Wyoming. Nonsignificant differences were reported for the remaining states and DC.
A new NCHS report presents findings on maternal smoking prevalence and cessation before and during pregnancy as collected on the 2003 U.S. Standard Certificate of Live Birth, for a 46-state and District of Columbia reporting area, representing 95% of all births in the United States.