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Data Driven Detroit (D3) provides accessible, high-quality information and analysis to drive decision-making that strengthens communities in Southeast Michigan.

Getting “Trashed” on Opening Day, 2015

We at D3, like many people throughout Detroit, love the Tigers Opening Day celebration. It is a special day that marks the beginning of warm weather, outdoor activities and of course another hopeful season of baseball. Each year throngs of Tigers fans (and those who like an excuse to celebrate) from all over the region head downtown to eat, drink and be merry in advance of the first Tigers home game. Today, as in previous years, thousands of cabin-fever-afflicted fans will visit their favorite tailgating spots, have a few beverages, grill a few ‘dogs, cheer on our team…. and then leave behind a ton of trash. Unfortunately, while the celebration is great for Detroit, it has typically left behind a mess that can take days to clean up.

Tasked with cleaning up much of this trash is Clean Downtown, a program paid for by downtown businesses that picks up trash from about 200 receptacles placed strategically throughout the central business district. They also pick it up from sidewalks, the middle of the street, and everywhere else. According to the Ryan Epstein, who manages the Clean Downtown program for the Downtown Detroit Partnership (DDP) in conjunction with Goodwill Industries, Detroit’s Opening Day celebration produces around ten tons of garbage, which is one of the their biggest trash days of the year. To put that in perspective, a Ford Focus weighs about one and a half tons.

While it is easy to pick up trash contained in cans, much of the Opening Day trash inevitably ends up on the ground, creating more of a burden for the Clean Downtown program and the hard-working crews who help to pick up Detroit’s streets and sidewalks. To help the Clean Downtown crews this opening day, we’ve created a map showing the locations of the receptacles.


 

If you’re a data geek as well as a baseball fan, we’ve made the receptacle locations downloadable via our data portal. The data include the locations of the Clean Downtown receptacles as well as those public receptacles supplied by the city.

Enjoy opening day, and thanks for helping to keep downtown beautiful.

Moms, Place, and Low Birth Weight, Part 2: Does Place Matter?

This is the second in a three-part series examining correlates of low birth weight in babies born in 2010, 2011, and 2012 in Detroit, Wayne County outside of Detroit, Oakland County, and Macomb County.  Low birth weight (LBW), defined as 2500 grams or less[1], is a significant contributor to Detroit’s alarmingly high infant mortality rate.[2]  We offer this analysis in the belief that a better understanding of factors influencing birth weight can help reduce the mortality rate.

The first blog post looked at the associations between birth weight and the mother’s age, education, marital status, ethnicity, and race; the level of prenatal care she received; and the area of residence for women within the city of Detroit.

This second blog post compares the findings for Detroit to those for the “Metro Region” — defined as Wayne County outside of Detroit as well as Oakland County, and Macomb County — on the same characteristics, in effect asking, “Does place matter?”

A glance at the average rates of low birth weight for single births (we exclude multiple births[3]) in Detroit (12%) and the Metro Region (6%) tells us that, yes, place does matter, but it does not tell us why or for whom the differences occur.

So here we’ll look at whether knowing place of residence (Detroit or the Metro Region) adds appreciably to what we already know; namely, that the overall LBW rate for single births (singletons) is twice as high in Detroit as in the Metro Region and how the factors listed above (from the first blog post) were related to birth weight in Detroit.  For example, in the first blog post we showed that, in general, as educational attainment increased for Detroit women, the rate of low birth weight rate decreased.  Does the LBW rate for Metro Region women follow the same pattern but at a lower rate?

Source of data

The data for this study came from birth certificate records of babies born in 2010, 2011, and 2012 with the mother’s residence in Wayne, Oakland, or Macomb Counties. The first blog in this series described the source in detail.

Age

In Table 1 and Figure 1, we compare the association between the mother’s age and the birth weight of her infant in the two regions  The rate for teens in Detroit having a single birth in 2010-2012 was 12%, in line with the rates for other age groups in Detroit up to age 35.  Metro Region teens, however, had a rate 3 to 5 percentage points higher than the rates for other age groups.  Because the Metro Region teens giving birth during these three years constituted just 6% of the total singleton births, their rate had little effect on the average Metro Region rate of 6%.  And place made much less difference in the LBW rate for teens than for other age groups.

The gap in LBW rates between the two regions widened as age increased. The rate for Metro Region women declined with increasing age while the rate for Detroit women through ages 30-34 stayed nearly constant.  The gap reached 7 percentage points for women ages 30-34 and 9 percentage points for women ages 35 and older.  To put these wide gaps into perspective, if Detroit women aged 30 and above had had the LBW rate of Metro Region women of the same age, there would have been 563 fewer LBW births to Detroit women over this three-year period: 421 rather than the 984 that occurred.  Clearly, for age, the place of residence mattered.

LBW_Post2_Table1_1

Table 1: Percentage of LBW singleton births by mother’s age, Detroit and Metro Region, 2010 – 2012

LBW_Post2_Figure1

Figure 1

Educational attainment

Next we turn to the relationship between educational attainment and birth weight. Table 2 and Figure 2 show that except for women with an eighth grade education or less, the low birth weight rate declined – sometimes very little — with increasing levels of education.  For the Detroit women, the most noticeable drop (2 percentage points) from the average rate[4] did not occur until women had a bachelor’s degree or higher – and that was just 5% of the women having single births during this period.  For Metro Region women, graduating from high school was associated with a drop of 2 percentage points in the low birth weight rate.  Receiving an associates or higher degree was associated with a further decline of 2 percentage points.

In contrast to age, then, the effect of educational attainment on birth weight was similar in both Detroit and the Metro Region:  The higher the level of education, the lower the LBW rate.

LBW_Post2_Table2_1

Table 2: Percentage of LBW singleton births by mother’s educational attainment, Detroit and Metro Region, 2010-2012

LBW_Post2_Figure2

Figure 2

Marital status

We divided the mother’s marital status into three categories:  never married, married, and widowed or divorced. The latter two categories accounted for 2% of the Detroit women (509) and 3% of the Metro Region women (2,726).  Because the widowed or divorced group is a relatively small group in both areas and one with two different marital situations, we have excluded it from the analysis.

For both Metro Region and Detroit women, marital status made a difference in the rate of low birth weight, with marriage conferring a 3 to 4 percentage point advantage in both areas (Table 3 and Figure 3). That advantage, however, was a smaller contributor to the average LBW in Detroit than in the Metro Region because a far smaller percentage of the Detroit women were married (19%) than of the Metro Region women (68%).

LBW_Post2_Table3_1

Table 3: Percentage of LBW singleton births by mother’s marital status, Detroit and Metro Region, 2010-2012

LBW_Post2_Figure3

Figure 3

Ethnicity and Race

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Table 4: Percentage of LBW singleton births by mother’s ethnicity, Detroit and Metro Region, 2010-2012

The Hispanic population constituted 10% of the Detroit population and 5% of the Metro Region population, and there was essentially no difference in their low birth weight rates (see Table 4 and Figure 4).  In this sense, place did not matter for the Hispanic rate.  In another sense, though, it did matter.  We could have expected that the Hispanic LBW rate would be lower even than 6% in the Metro Region simply because of the overall average difference in the two regions’ rates, but it was not.

The Non-Hispanic rates differed by 6 percentage points, however, reflecting the overall average singleton LBW rates of 12% in Detroit and 6% in the Metro Region.  This difference is not surprising since the Non-Hispanic population of the Detroit women giving birth to one or more singleton births from 2010-2012 was 90% Black, with its average rate of 13%, while the comparable Non-Hispanic population of Metro Region women was 74% White with an average rate of 5%[5]. (See Table 5 and Figure 4).

Figure 4 starkly illustrates that both place (Detroit and Metro Region) and race (Black and White) mattered for babies’ birth weight, although for both Blacks and Whites place had less effect than simply being Black or White.  Race-place interaction is something we will explore in the third blog post in this series.

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Table 5: Percentage of LBW singleton births by mother’s race, Detroit and Metro Region, 2010-2012

LBW_Post2_Figure4

Figure 4

Prenatal care

While the relationship between the level of prenatal care and birth weight followed the same pattern in the two regions, receiving inadequate care had a greater impact on birth weight for Detroit women than for Metro Region women (Table 6 and Figure 5).  In Detroit, receiving inadequate care as opposed to adequate or intermediate care was associated with an increase of 5 points in the percentage of LBW babies. One-sixth (16%) of the singleton babies born from 2010-2012 to Detroit women receiving inadequate prenatal care were low birth weight babies.  The singleton LBW rate for Metro Region women receiving inadequate care was lower but still constituted 10% of their singleton births during this three-year period.

Of particular note in Table 6 are the number and percentage of women who received inadequate prenatal care[6]:  an average per year of 1,665 women (18%) in Detroit from 2010-2012 and 3,099 women (9%) in the Metro Region.

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Table 6: Percentage of LBW singleton births by mother’s level of prenatal care, Detroit and Metro Region, 2010-2012

LBW_Post2_Figure5

Figure 5

Geographical distribution of low birth weight babies in Detroit and the Metro Region

Figure 6 places Detroit in the context of the three-county Metro Region, illustrating the percentage of low birth weight singleton babies born to mothers in the years 2010-2012 by census tract.  While Detroit has the greatest concentration of census tracts with comparatively high LBW rates, there are clusters of higher rates along Grand River Avenue in Macomb County; in the Pontiac area; just north of the Detroit boundary; and in southern Wayne County.

Region_Birth_Weight

Figure 6

Summary

We began this blog post by asking, “Does place matter?”  To phrase the question differently, suppose that we want to predict how likely women 30 and older in the Metro Region would be to have a low birth weight baby.  We know that overall the average low birth weight rate for 2010-2012 was 6 percentage points higher for women living in Detroit than in the Metro Region (12% vs. 6% respectively).  We also know, from the first blog post, the average LBW rate for women  age 30 or above living in Detroit.  So we can ask the question like this: From these two pieces of information, would we get a reasonable prediction of the LBW rate for women 30 and older living in the Metro Region?

The answer:  Probably not.   The answer, though, depends on the characteristic being investigated.  Place made virtually no difference in the LBW rate for Hispanic women in the two areas (both had a quite low rate: 6%) and small differences for teenagers, women with an eighth grade education or less, and Black women.  Area of residence did influence the LBW rate for women aged 20 and above (the rate increased with age in Detroit and decreased or leveled off in the Metro Region) and for women with different levels of prenatal care (the difference was especially large for Detroit women receiving inadequate prenatal care compared to such women in the Metro Region).  For education and marital status, the patterns were more likely to match expectations.

In the third blog, we will take this examination of associations between mothers’ demographic characteristics and their children’s birth weight further.  Because a major difference between Detroit and Metro Region women giving birth during this period is the racial composition of the two groups, and we know that race can have major implications for an individual’s opportunities and well-being, it makes sense to examine the combinations of place and race on rates of low birth weight for the various characteristics of the mother.  In the third blog, then, we construct four place-race groups (Detroit Blacks; Detroit Whites; Metro Region Blacks; Metro Region Whites) enabling us to ask, “Does place trump race in its effect on birth weight?”  As the next post will show, for the characteristics we examined, the answer is clear.

 


[1] Very low birth weight is defined as less than 1500 grams.  In this analysis, very low and low are aggregated as “low” birth weight.

[2] Brown, Sally.  “Detroit Task Force to Reduce Infant Mortality,” Henry Ford Health System News and Research, October 19, 2011.

[3] Multiple births are excluded because they have a known high rate of low birth weight.

[4] As a result of missing data on educational attainment, the average rate for the entire area shown in the table (here 11% for Detroit) differs from the average rate for the entire group (12% for Detroit).

[5] 90% of the Non-Hispanic population of Detroit women giving birth in 2010-2012 were Black, 7% White, and 3% other race, while 74% of the Non-Hispanic mothers in the Metro Region were White, 18% were Black, 6% Asian or Asian Indian, and 2% other race.

[6] The Kessner Index assigns a value of adequate, intermediate, or inadequate to the level of prenatal care a woman received.  The Michigan Department of Community Health Division of Vital Records and Health Statistics explains the Index as,  “… a classification of prenatal care based on the month of pregnancy in which prenatal care began, the number of prenatal visits and the length of pregnancy (i.e. for shorter pregnancies, fewer prenatal visits constitute adequate care).”

Data Show Where Detroit’s Students Live

Detroit is a big place, and the demand for schools can’t be the same equally across the city, especially since there are such large differences between thriving and disinvested areas. Because the education landscape continues to be a topic of much discussion, we recently put an approximated student location data set to good use by creating an interpolated model showing where Detroit public school students are concentrated.  The model indicates that there are several areas of Detroit with higher concentrations of students attending public schools (defined here as local, charter and Education Achievement Authority).

Using interpolation to create a modeled surface entails approximating values of certain characteristics at all locations between known observations. In this case, our observations were the number of students per block, and that number was spatially located at the center of each block. Between the centers of each census block, we applied a mathematical formula that models the likely value at each point, taking into consideration the values of student counts in nearby blocks. The interpolation process is based on the premise that observations that are close in space are likely to have similar value, so in-between values are estimated based on nearby actual observations.

The resulting model can’t be used to determine actual counts at any one location. For example, the model erroneously shows students residing on Belle Isle, which is the result of Belle Isle being a large census block. In addition, the model could look considerably different depending on the assumptions made (the size of the grid or the weighting, for instance). Instead of regarding these values as actual observations, the model should be regarded as showing a spatial trend. While not precise, this smoothed spatial trend allows us to see areas of generalized higher concentration.

Modeled map showing where students are concentrated.

Modeled map showing where students are concentrated.

In the map above, orange and red indicate the highest numbers of students who attend public Detroit schools per area. As you can see, concentrations of these students exist around Lafayette Park, within the apartment complexes along 1-75 between Mack and Warren, and in Southwest Detroit, with smaller concentrations in Warrendale and around East English Village, on the far east side.

Conversely, large sections of the interior of Detroit, especially east and southeast of Hamtramck, show the fewest students. This situation isn’t completely surprising, given that this area of the city has high vacancy rates, large numbers of vacant lots and some of the worst building conditions in the city, according to the Motor City Mapping survey. The map below shows numbers of existing structures as a percentage of parcels per block group. The lighter colors represent areas of the city that have a higher percentage of vacant lots. While not perfectly accurate, these areas line up fairly well with the areas in the previous map showing the lowest concentrations of students — with the exception of Southwest Detroit. Southwest Detroit, with its large Hispanic population, is known to have higher birth rates than other parts of the city. These birth rates would explain the higher concentrations of students despite a higher number of vacant lots.

PercentStructures

Percent Existing Structures, by Block Group, Winter 2013

Generally speaking, this model illustrates the areas of the city where a relatively higher school capacity (higher number of student “seats”) is needed and areas where less capacity may be warranted. Of course, there are other criteria to evaluate in addition to proximity to students. Factors such as the number and quality of existing nearby schools, physical barriers such as highways, and societal barriers such as language and ethnicity are all important considerations as well.

While these data and maps are not prescriptive by themselves, they represent an important tool for policymakers working toward improving the climate for education in Detroit. Further layers of data would need to be added to this analysis to paint a more precise picture, but, optimistically speaking, the data and tools are becoming available to make data-driven decisions on education.

Exploring Student Dispersion Maps

Since the 2011-12 school year, Data Driven Detroit (D3) has created a series of maps that illustrate the spatial patterns related to where students from different areas in Detroit attend school or where students from different schools live (see our previous blog post introducing the project). This year’s data, from the October 2013 student count, allowed us to compile maps for almost all publicly funded schools in the city, leaving out only a few that were incorrectly identified to be outside the city. Using the 2013-14 Student Dispersion Tool that D3 has published, interested parties can view and download maps showing the dispersion patterns of each public school in the city to see where its students live. Additionally, with the filters provided, users can easily contrast results between schools in the same category or at the same level for a more appropriate comparison.

In this most recent update of the data and maps, the category breaks are consistent across all maps for comparison’s sake. The same color blue in one map represents the same number of students in all the maps. However, since schools are often very different in the size of their student bodies, we also created maps showing percentages of students living in a tract. In this post, we’ve selected a few maps from the 2013-14 collection, from across the spectrum of school types, to highlight. We encourage you to view all the schools with the new tool.

 

Cass Technical High School

Cass Tech is Detroit’s original and most recognized magnet school. It is a citywide school with a competitive application and examination process. It is located just north of the Chrysler Freeway and downtown Detroit in a brand new, modern glass and steel building. Cass Tech boasts an impressive list of notable alumni and has a strong educational reputation.

Student Dispersion 13-14_Cass Technical High School_00554

Number of Students Who Attend Cass Tech, by Tract

The first thing you notice when you look at Cass Tech’s dispersion map is that a lot of students travel very long distances to attend the school, including many students who reside outside the city’s borders. While it is somewhat expected at a magnet school that students would travel farther to get to school, it does raise the question of whether those distances cause academic problems or strains on the student’s family. In addition, the larger series of dispersion maps shows that a fairly long commute is common for Detroit students.

Student Dispersion 13-14_Pct Attending_Cass Technical High School_00554

Students Attending Cass Tech, By Tract, as a Percentage of Student Body

Because Cass Tech is a competitive school, one might expect that students from wealthier areas of Detroit would send larger numbers of students there. However, looking at the dispersion of total students, it is unclear whether there are areas with disproportionate numbers of students attending Cass. There are good showings from some typically strong neighborhoods such as the University District (7 mile and Livernois) and Grandmont/Rosedale (Grand River and M-39) but nothing that looks extremely uneven. In fact, the largest numbers of students from any tract are to the north and east of Hamtramck, which does not boast fine housing stock or higher salaries. In fact, even tracts in those areas with a high degree of abandonment and disinvestment, such as those neighborhoods east of Hamtramck, have a decent representation.

The map showing the percentage of students attending Cass Tech by tract shows the equal distribution of students even more plainly. No tract in Detroit houses more than 4.9 percent of the Cass Tech student body. Cass, at first glance, appears to truly serve the whole city.

 

Phoenix Elementary-Middle School

In contrast to the even distribution of Cass Tech students, Phoenix Elementary in Southwest Detroit shows a highly concentrated dispersion pattern. While elementary students typically don’t travel as far as older students, Phoenix’s students are more local than most. Phoenix is an Education Achievement Authority school. As such, it was in the lowest 5 percent in performance for all schools statewide when the state took over administration of the school. There has been some speculation ever since the state created the EAA district that the worst-performing schools (including EAA schools by rule) would retain the least mobile students with the fewest resources because those students who had the ability to attend better-performing schools farther away would likely do so. In addition, Detroit educators often say that strong ethnic bonds in Southwest Detroit cause students from Southwest Detroit to tend to stay at schools in that area with high numbers of Latino students. Both of these reasons, and probably others, likely contribute to Phoenix’s tight distribution of students, though we can’t say that with certainty. Further study is needed.

Student Dispersion 13-14_PhoenixElementarySchool_04554

Number of Students Who Attend Phoenix Elementary, By Tract

Student Dispersion 13-14_Pct Attending_PhoenixElementarySchool_04554

Students Attending Phoenix Elementary, By Tract, as a Percentage of Student Body

 

 

 

 

 

 

 

 

Warrendale Charter Academy

Warrendale Charter Academy is a mid-sized K-8 charter school on Detroit’s west side, near Dearborn. This charter school is interesting because it draws students mostly from the west side of Detroit and a lot of students from adjacent tracts. In fact, the percentage maps shows that at least 40 percent of its students come from adjacent tracts. Also, even though it is close to the border of other cities, the school draws almost exclusively from Detroit (this is less the case with other charters). So why is it that some schools, charter or not, draw from so much farther away and even from other cities? It may be a deliberate recruitment strategy, or it may be based on performance or reputation or other factors. Perhaps there are stronger neighborhood bonds in this area than in other areas of Detroit. More study is certainly needed.

Student Dispersion 13-14_Warrendale_Charter_Academy_08934

Number of Students Who Attend Warrendale Charter Academy, By Tract

Student Dispersion 13-14_Pct Attending_Warrendale_Charter_Academy_08934

Students Attending Warrendale Charter Academy, By Tract, as a Percentage of Student Body

 

 

 

 

 

 

 

 

Denby High School

Denby High School is an Educational Achievement Authority school on the east side of Detroit. The dispersion map for Denby, in comparison to Cass Tech, or even Western International, shows a student population highly concentrated within east-side neighborhoods. In addition, very few students who attend Denby live outside the city, despite the fact that the school is relatively close to the city border. While it is no surprise that few, if any, students attend Denby from the nearby “Pointes,” because of the strong schools systems and different demographics in those areas, it is mildly surprising that there are not more students coming from Eastpointe and Warren. The neighborhood directly around Denby is still in pretty good shape, according to Motor City Mapping results. However, just a few blocks west, across Hayes Road, is a highly disinvested area where vacant lots outnumber homes. Since this area likely has fewer school-age children, perhaps it limits the reach of Denby into other parts of the city. Denby’s limited reach helps to reinforce the trend that EAA schools on average tend to draw students from a smaller geographic area.

Student Dispersion 13-14_Denby High School_00902

Number of Students Who Attend Denby High School, By Tract

Student Dispersion 13-14_Pct Attending_Denby High School_00902

Students Attending Denby High School, By Tract, as a Percentage of Student Body

 

 

 

 

 

 

 

 

There’s a Lot More to See!

As you can see from this post, each school we’ve highlighted has a unique pattern. Data Driven Detroit has maps for each publicly funded school in Detroit and has made them available online through an interactive graphic. The maps are very interesting to look at. Check them out at:
http://datadrivendetroit.org/studentdispersion2013/

Next Up in This Series

We’ll take a more in-depth look at average commuting distances per school.

“Data Highlights” are a new D3 blog feature focused on sharing some of the interesting trends and patterns we’ve noticed over the course of our work!  We hope that these insights give a unique perspective into our work, and increase interest in using data to make informed decisions.

Moms, Place, and Low Birth Weight, Part 1: Detroit

In an influential January 30, 2014 Detroit News article entitled “Detroit is Deadliest City for Children,” the author, Karen Bouffard, wrote, “In 2010, Detroit (population about 713,000) and Cleveland (population about 390,000) had the highest infant mortality rates of Big City America: 13.5 deaths for every 1,000 live births — higher than in Panama, Romania and Botswana. The measure includes deaths from all causes in a child’s first 12 months….” [1] After 2010, Detroit’s rate dipped a bit to 12.6/1,000 in 2011 but then jumped to 15.0/1,000 in 2012, the latest year for which statistics are available.[2]  The grim reality this article highlighted prompted Detroit policy makers to take action, and they joined other efforts underway in the city and at the state level to combat infant mortality.  For example, one of these programs is the Detroit Regional Infant Mortality Task Force’s program Sew Up the Safety Net for Women and Children.[3]

This three-part blog series examines one factor, low birth weight (“LBW”), which is closely associated with higher infant mortality rates.[4]  We look at information recorded on the infant’s birth certificate in an effort to understand whether there are demographic and socioeconomic characteristics of the mother that can help identify women most at risk of having a LBW infant.  We are not examining medical conditions of the mother – that’s beyond our expertise—nor are we including women who gave birth to two or more babies (e.g., twins or triplets) because infants in multiple births have a known high risk of low birth weight.

In this first blog of the series we focus on Detroit exclusively, investigating the associations between the rate of low birth weight and (1) the mother’s age at the birth of the child; (2) her educational attainment; (3) her marital status; (4) her race; (5) her ethnicity; (6) the adequacy of the prenatal care she received; and (7) the distribution of LBW infants within the city of Detroit (by census tract of mother’s residence).

The second blog focuses on the same factors for the metro Detroit region, which for the purpose of this blog we define as Wayne County outside of Detroit, Oakland County, and Macomb County (“Metro Region”).  We compare the associations found for that region with those found for Detroit as a way of asking, “Does place matter?”

If we find that place does matter (and it seems to), we ask in the third blog whether there is something else besides place of residence that can contribute to our understanding of differences in low birth weight rates.  In particular we investigate the effect of race and place together.

As we conducted these analyses, we found that the results kept raising more questions than we could answer, so we consider this series to be a starting point for deeper investigations.  We hope the report motivates readers to offer their insights and findings and suggest other ways of looking at the birth record data or other sources to better understand factors influencing low birth weight.  A further blog series will examine correlates of inadequate prenatal care, another factor associated with higher infant mortality.

Source of data

The data for this study came from birth certificate records of babies born in 2010, 2011, and 2012 with the mother’s residence in Wayne, Oakland, or Macomb Counties. No names or home addresses were included in the records, but we were able to identify the census tract of the mother’s residence.  Census tracts with fewer than six births during the three year period were suppressed.  Low birth weight is defined as less than 2500 grams.[5]  In all the analyses, missing data have been eliminated.  Of the total number of women with single births (women with multiple births were excluded) in Detroit during this period, 11 records had missing birth weight information and have been eliminated from all the analyses. Individual variables had differing numbers of records with missing data.  In cases where the percentage of missing data was 1% or greater of the total records, we note the percentage of records with missing data.  We used three years of data to smooth the year-to-year fluctuations.

 Detroit Births

Over the three-year period from 2010-2012 there were 30,244 single births (“singletons”) to mothers living in Detroit (30,233 with birth weight on the birth certificate).  88% of these 30,233 were of normal birth weight, while 12% (3,478) were of low birth weight.  This is an average of 1,192 LBW singleton babies per year from 2010 – 2012.

Age

Table1

Table 1: Percentage of low birth weight singleton births by mother’s age, Detroit, 2010-2012

We looked first at the relationship between mother’s age and the birth weight of the infant.  We divided the ages of the mothers into five groups: teens (younger than 20); 20-24; 25-29; 30-34; 35+.  As Table 1 shows, 11 to 12% of the age groups through age 34 had LBW babies.  At ages 35 and higher, this percentage increased to 15%.

For women giving birth in Detroit during this three-year period, age did not affect the likelihood of having a low birth weight baby until age 35 and above.

Education

Next we turned to the effect of educational attainment on the likelihood of having a low birth weight baby.[6]

LBW_Post1_Table2

Table 2: Percentage of LBW singleton births by mother’s educational attainment, Detroit, 2010-2012

Figure 1 illustrates the perhaps surprising finding that women with an eighth grade education or less had the lowest rate of LBW babies.  As we discuss further in the blog, this is due at least in part to the characteristics of the women in this educational category, but we leave this until we have looked at other factors.

 

 

LBW_Post1_Figure1

Figure 1: Percentage of LBW singleton births by mother’s educational attainment, Detroit, 2010-2012

There were few women in this Detroit group with a Master’s degree or a doctorate or professional degree (data not shown).  The larger group of women who held a bachelor’s degree or higher had a low birth weight rate of 9%, two or three percentage points lower than women with less education.

 

 

Marital status

LBW_Post1_Table3

Table 3: Percentage of LBW singleton births by mother’s marital status, Detroit, 2010-2012

We divided the mother’s marital status into three categories:  never married, married, and widowed or divorced. 2% of the Detroit women (509) were divorced or widowed.  Because this is such a small group and one with two different marital situations, we have excluded them from the analysis.  Table 3 illustrates that married women had a three percentage point lower rate of low birth weight babies than women who had never been married.

Race and Ethnicity

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Table 4: Percentage of LBW singleton births by mother’s race, Detroit, 2010-2012

Race on the birth certificate is coded into 17 different categories.  We collapsed the 17 categories into three:  Black, White, and Other.  Of the 30,000+ women, 81% were classified as Black, 8% as White, and 10% as Other.  The Other category includes all those women who were not classified as Black or White (3,092).  Because 96% of Other Race was Hispanic, we have eliminated them from the analysis in order to not overlap with the Hispanic identity analysis.

LBW_Post1_Figure2

Figure 2: Percentage of LBW singleton births by mother’s ethnicity and race, Detroit, 2010-2012

There was a gap of five percentage points in percentage of singleton LBW babies between Black (13%) and White (8%) groups. If Blacks had had the White rate of 8% instead of 13%, there would have been more than 1,100 fewer Black infants of low birth weight during the three-year period.

 

LBW_Post1_Table5

Table 5: Percentage of LBW singleton births by mother’s ethnicity, Detroit, 2010-2012

 

Table 5 and Figure 2 show that Hispanic women had a substantially lower LBW rate than Non-Hispanic women.  Now we can start to tease out why women with an eighth grade education or less had a much lower rate of low birth weight than women with higher educational attainment.  First, 59% of the 1,180 women with an 8th grade education or less were Hispanic in contrast to the 10% of the total population of 30,244 women who were Hispanic.  Second, those women with an 8th grade education or less were more likely to be married (51%) than the total population of women (19%), and marriage also conferred a birth weight advantage on the infant.

Adequacy of prenatal care

LBW_Post1_Table6

Table 6: Percentage of LBW singleton births by mother’s level of prenatal care, Detroit, 2010-2012

The Kessner Index assigns a value of adequate, intermediate, or inadequate to the level of prenatal care a woman received.  The Michigan Department of Community Health Division of Vital Records and Health Statistics explains the Index as,  “… a classification of prenatal care based on the month of pregnancy in which prenatal care began, the number of prenatal visits and the length of pregnancy (i.e. for shorter pregnancies, fewer prenatal visits constitute adequate care).”

As is evident from Table 6, both adequate and intermediate prenatal care had similar rates of low birth weight, even if not precisely the same percentage, while inadequate prenatal care, which included no prenatal care, was associated with a five to six percentage points higher rate.[7]  Note that fully 18% of the women had inadequate prenatal care.

Geographical distribution of low birth weight babies in Detroit

Detroit_LBW_2010to2012

Figure 3: Geographical distribution of LBW singleton births in Detroit, 2010-2012

 

 

Figure 3 displays low birth weight rates (grouped into ranges) for all census tracts in Detroit.  Except for areas of Southwest Detroit (which have a high Hispanic population), there does not appear to be any readily-discernible grouping of census tracts by birth weight.

 

 

Summary

This first blog examined social and demographic correlates of the birth weight of babies born in 2010-2012 to women residing in Detroit. We looked at the associations between birth weight and the mother’s age, her education, marital status, ethnicity, race, and the level of prenatal care she received.

Overall, ethnicity, race, and level of prenatal care had the greatest effect on birth weight.  The Hispanic low birth weight rate was six percentage points lower than the rate for Non-Hispanics, and the rate for Whites was five percentage points lower than the rate for Blacks.  Adequate and intermediate levels of prenatal care were associated with a five to six point advantage in birth weight rates over inadequate prenatal care.

Education and marital status were less strongly related to birth weight, although being married versus being unmarried conferred a three percentage point advantage, and having a bachelor’s degree or higher was associated with a two percentage point lower rate of low birth weight than having less education.  Age made little difference until age 35 when the rate of LBW babies increased by three-to-four percentage points over younger ages.

In the next blog, we look at the same factors in the “Metro Region”; that is, Wayne County outside of Detroit, Oakland County, and Macomb County considered as one region.  We contrast the findings for the Metro Region with what we saw for Detroit to ask, “Does place matter?”


[1] Bouffard, Karen.  “Detroit is Deadliest City for Children, “ The Detroit News, January 30, 2014

[2] Source:  1989-1999 Michigan Death Certificate Registries; 1999-2011 Geocoded Michigan Death Certificate Registries; 2012 Michigan Death Certificate Registry., 1989-1999 Michigan Birth Certificate Registries;2000-2012 Geocoded Michigan Birth Certificate Registries., Vital Records and Health Statistics Section, Division for Vital Records and Health Statistics, Michigan Department of Community Health

[3] http://www.henryfordwestbloomfield.com/documents/SUSN/Provider%20Fact%20Sheet%20Final.pdf

[4] Brown, Sally.  “Detroit Task Force to Reduce Infant Mortality,” Henry Ford Health System News and Research, October 19, 2011.

[5] Very low birth weight is defined as less than 1500 grams.  In this analysis, very low and low are aggregated as “low” birth weight.

[6] 1.5% of the records were missing educational attainment.

[7] 7.4% of the group of 30,000+ women had missing data on this variable.

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