- by Molly Walker
Staff Writer, MedPage
Overall fertility rates and reproductive rates have fallen among U.S. women from 1990 to 2014, despite a 10-year spike from the mid-1990s to the mid-2000s, said CDC researchers.
The total fertility rate, which measures the potential impact of current fertility patterns on reproduction or completed family size, declined approximately 10% from 2,081.0 births per a hypothetical cohort of 1,000 women in 1990 to 1,862.5 per 1,000 in 2014, reported Brady E. Hamilton, PhD, and Sharon E. Kirmeyer, PhD [deceased], of the CDC Division of Vital Statistics.
These rates declined 5% from 1990 to 1997, with a 8% spike from 1997 to 2007, before falling 12% from 2007 to 2014 -- with a less than 1% increase from 2013 to 2014.
Writing in National Vital Statistics Reports, the authors said that from 1990 to 2014, the total fertility rate was "below replacement level" -- which is defined as the level that a given generation can exactly replace itself -- in every year except 2006 and 2007. It is defined as 2,100 births per 1,000 women.
Total fertility rates and gross reproduction rates fell among all races and Hispanic subgroups during the examined time period with the exception of Cuban American women, they noted.
The total gross reproduction rate (defined as the average number of daughters per 1,000 births, assuming none of them were to die) also exhibited a 10% decline -- dropping from 1,015 per 1,000 in 1990 to 909 per 1,000 births in 2014. The authors noted that the gross reproduction rate closely parallels the total fertility rate because of the "narrow variability of female births relative to male births."
With a decline in birth rates comes a decline in population. If the intrinsic rate of natural increase, or the rate of change of population size resulting from the continuance of age-specific birth and mortality rates over a given year of time, is negative, that indicates a population decline. The rate in 2014 was -3.7 per 1,000. In fact, the authors noted that the rate has been negative every year from 1990 to 2014, except for 2006 and 2007.
This was also the first time that the report examined reproduction and intrinsic rates by race and Hispanic origin of the mother for non-Hispanic white, non-Hispanic black, and Hispanic groups, said the authors.
These trends varied by demographic groups. Total fertility rates for Hispanic women exceeded replacement every year during the examined time period, but rates for non-Hispanic and Asian/Pacific Islander women were "consistently below replacement" during that time.
But the largest declines in gross reproduction rate from 1990 to 2014 were seen among American Indian/Alaska Native women (-41%), Hispanic women (-28%), and non-Hispanic black women (-26%). By contrast, the gross reproduction rate among non-Hispanic white women fell 5% during that time. The net reproduction rate (which incorporates mortality rates into the estimates) saw similar, albeit slightly smaller declines among these groups.
The authors noted that the difference between gross reproduction rate and the net reproduction rate has "diminished considerably over the year, reflecting the decline in age-specific mortality rates of women in childbearing years."
