The phrase "decrease in birth rate" is correct and can be used in written English.
You could use it to refer to a decrease in the number of babies born in a particular region or population over a certain period of time. For example: There has been a steady decrease in birth rate over the past decade in the United States.
The decrease in birth rate from the 1870s, eugenic concerns with "degeneration", ideas about the effects of environment on how children develop, and the relative novelty of only children generated a lot of unease, which has somehow stuck with us to this day.
Korea has a rapidly aging population due to a decrease in birth rate and an increase in life expectancy.
A time-related decrease in birth rate, with a mean annual frequency of 0.16 (95% confidence interval, 0.09 to 0.23) per 10,000 neonates, was reported by Castellani et al. [ 5].
Another systematic review found an 11%% lower birth rate [ 13], an effect which is smaller than the decrease in birth rate found in our study, possibly because our study includes particularly traumatic caesarean sections as women had near-misses.
At this threshold, TSG inactivation and oncogene activation rates evolved toward low values, implying a large decrease in birth rate through the assumed trade-off defined by function ω u0,u1) (see section Materials and Method).
We find a significant and persistent increase in infant mortality rates and a more modest decrease in birth rates as a result of state centralization.
This trend is the result of several factors including drastic decrease in birth rates, increasing longevity of people with the improved healthcare, improved quality of life and the like.
Arellano and Bover (1995) use a time series model of female labor force participation and conclude that the increase in women's education and the decrease in birth rates (after controlling for endogeneity by treating education and fertility endogenous) are the main factors underlying the increase in female labor supply during the period 1976 1991.
The decrease in birth rates in some parts of the world is no reason for alarm.
The Japanese population is rapidly aging as a result of a post–World War II baby boom followed by a decrease in birth rates.
Since the implementation of these measures, a significant decrease in birth rates of neural tube defects, orofacial clefts, congenital heart defects and diaphragmatic hernia has been reported [4], [5], [6], [7].
