In this release of Quarterly Provisional Estimates,NCHS presents provisional estimates of selected reproductive indicators from birth data for 2014 through the second quarter of 2016. Estimates for 2014 and 2015 are based on final data (1-2). The estimates for the first and second quarter of 2016 are based on all birth records received and processed by NCHS as of August 28, 2016. Estimates are presented for: general fertility rates, and age-specific birth rates,total and low risk cesarean delivery rates, preterm birth rates and other gestational age categories. These indicators were selected based on their importance for public health surveillance as well as the feasibility of producing dependable estimates using available provisional data (1-3). Future quarterly releases will include additional birth indicators from natality data (4). Quarterly estimates are compared with estimates for the same quarter of the preceding year; for example, or the second quarter of 2016 is compared with the second quarter of 2015. For comparability with rates for 12-month periods,the quarterly (3-month) rates maintain been annualized to present births per year per 1000 population that would be expected whether the quarter-specific rate prevailed for 12 months. In addition, the rates and percentages for a 12-month period ending with each quarter (i.e., and 12-month moving average) are presented to account for seasonality. Estimates for the 12-month period ending with the fourth quarter in each year can be interpreted as an annual provisional estimate for that year. Differences are reported only whether statistically significant (P
Source: cdc.gov