Examining Trends of Teen Birth Rates in Milwaukee, Wisconsin

Even though the rates of teen pregnancy and births for teenagers have experienced significant declines, teen pregnancy remains a significant problem in the United States.  The pregnancy rate for young teenagers aged 15-17 years fell from 77.1 per 1,000 females in 1990 to 41.5 in 2004 [1].  Correspondingly, the birth rate for teens of this age declined 43%, from its peak at 38.6 in 1991 to 22.0 in 2006 [2, 3].

Examining birth rates for all teens (ages 15-19) in 2006, the birth rate in the United States rose 3 percent, from 40.5 live births per 1,000 15-19 year old females to 41.9.  This is the first rise in teen birth rate since 1991 [3, 4].  When looking at the birth rate for young teenagers (15-17) there was a rise of 3 percent to 22.0 per 1,000 in 2006 [4].

In this study, we specifically focused on evaluating the trending of birth rates for young teenagers aged 15-17.  Although it may be too soon to identify this 3 percent rise as the beginning of an upward trend, it is important for us to closely examine the data.

Fig. 1 shows the trending of birth rates by maternal age group, 15-17 and 18-19 years old from 1971 to 2005.  Compared to the national average, the City of Milwaukee still has a higher teen birth rate [1, 6, 7, 8]. The national average of the birth rate for teenagers aged 15-17 years declined 42% from its peak at 38.6 in 1991 to 22.4 in 2003[9].

Fig. 2 shows teen (ages 15-17) birth rates for the City of Milwaukee from 1990 to 2006.  The teen birth rates fell between 1991 and 2004, from 95.8 births per 1,000 females aged 15-17 years in 1991 to 54.4 in 2004.  However, it rose 3.7 percent to 56.5 in 2005. 

Although the birth rate fell 0.7 percent to 55.4 in 2006 from 56.5 in 2005, it seems that this rate may continue to trend down to the lowest level without further efforts.

Although these downward trends are hopeful, we need to remain active in our efforts to continue to reduce teen birth rates.  When viewing these birth rate trends, it is also important to note the implications of the peak in teen births from 1991-95.  The daughters of these teen mothers are now reaching their teenage years.  Given that girls born to teen mothers are more likely to become teen mothers themselves, we might expect the teen birth rates to peak again unless we intervene.

As we seek ways to expand our efforts in reducing teen birth rates, it may be helpful to look more closely at the data to help provide clues for specific areas we may want to focus our resources.  For example, Fig. 3 shows the fluctuation in the monthly averages of birth rates among young teenagers aged 15-17 years in three different periods, 1993-96, 97-2000 and 2001-04, respectively.  Birth rates have been tending to decrease since 1993 (P<0.05).  There was a significant monthly fluctuation (P<0.05) with the highest birth rates being observed in March in all three periods.  Counting backwards, it may be concluded that the highest period of sexual activity (that resulted in actual teen births) occurred in mid-summer. 

Armed with this knowledge, we may want to explore making special efforts during the summer to increase health education around safe sex, as well as investigate ways to better occupy youth's summer schedules.

Fig.4 shows the result of regression analysis with three trend lines in order to analyze the trend of teen birth rates in an effort to forecast and set the goal for birth rates for young teenagers in 2015.  By using different methodologies, three different predicted birth rates were calculated, 9.1, 35.9 and 53.2 births per 1,000 females.

Although it may be difficult to attain, it would be feasible to set a goal of 30 births for 1,000 females: a 46% reduction in 2015, based on the current rate of 55.4 births per 1,000 young teenagers aged 15-17 years.

Next steps for us will be to examine the literature around seasonality and birth rates to develop a better understanding for these trends as well as how best to address them.

References

1. Ventura SJ, Abma JC, Mosher WD, Henshaw, SK.  Estimated Pregnancy Rates by Outcome for the United States, 1990-2004.  National Center for Health Statistics.
2. Ventura SJ, Abma JC, Mosher WD, Henshaw SK.  Recent trends in teenage pregnancy in the United States, 1990-2002.  National Center for Health Statistics.
3. Teen Birth Rate Rises for First Time in 15 Years for Immediate Release: December 5, 2007. National Center for Health Statistics.
4. QuickStats: Pregnancy, Birth, and Abortion Rates for Teenagers Aged 15--17 Years --- United States, 1976-2003 CDC MMWR 54(04); 100, 2005.
5. Hamilton BE, Martin JA, Ventura SJ.  Births: Preliminary Data for 2006.  National Vital Statistics Report.  December 2007, 56(7) 1-18.
6. National Vital Statistics Reports Births: Final Data for 2005 DED Vol 56 (6)
7. Preliminary Births for 2004. CDC January 11 2007.
8. Birth Preliminary Data for 2005. CDC January 11, 2007.
9. Births: Final Data for 2005. CDC December 5, 2007.
10. Quick Stats: Pregnancy, Birth, and Abortion Rates for Teenagers Aged 15--17 Years --- United States, 1976-2003 CDC February, 2005.