Neighborhood provides the environment for pregnant mothers

Journal: Environmental Health Perspectives
Date: March 2012

Summary
Where a woman lives during her pregnancy can have consequences for her baby. At the OHSU Moore Institute, we often say, “while the mother is the environment for the baby, society is the environment for the mother.” In essence, the mother’s surroundings have a profound effect on her stress levels and her ability to access healthy opportunities , as she carries and grows the next generation. This research brief is about a study showing a direct link between the built environment where women lived while pregnant, and the birthweight of their babies.

Birthweight is important, because DOHaD science has shown the link between low birthweight and an increased risk for chronic disease later in the baby’s life. In other words, the quality of a woman’s surroundings during pregnancy can predict health risks in her baby - the next generation.                                   

In 2008, a group of researchers set out to investigate the relationship between the quality of a residential area and negative birth outcomes. The study combined data from direct observations, tax assessment information, public safety reports, vital records, and U.S. Census data, and overlaid that onto 17,000 tax parcels within 873 blocks of an area in Durham, North Carolina. The researchers identified seven categories of important residential features, with variables in each category, to describe residential quality.

Features of residential quality:

A score was generated for each of the residential categories, using statistical analysis to rank the many variables within each category. The more instances of a variable, the higher the score. For tenure, the more rentals meant a higher score.

Birth outcomes of interest
Researchers were interested in five adverse birth outcomes. Three of these are well known: preterm birth (less than 37 weeks), small for gestational age (less than 10^th percentile of birthweight for gestational age), and low birthweight (less than 5.5 pounds). The other two outcomes were for a continual scale of fetal weight, which is a more precise way to determine weight for gestational age. For brevity, this research brief will only summarize the first three outcomes listed here.

All the information was gathered through anonymous public records. Researchers used National Center for Health Statistics for to gather information on singleton births during 2000-2004. They then sorted the births that occurred between 20-44 weeks’ gestational age by sex (males and females grow differently). They also collected data on the mothers’ ages, which birth this was for them, their level of education and marital status, as well as their race and ethnicity. Ultimately, they analyzed 4,279 birth records for this study.

What they found
All categories of residential quality were associated with preterm birth, small for gestational age and low birthweight babies. However, there were some maternal characteristics that confounded the results – meaning researchers couldn’t be confident other life factors such as educational level or age were partly responsible for the results. So, they adjusted the results for maternal factors and found the following:

• Preterm birth (PTB):
  Living in an area with high amounts of housing damage, property disorder, nuisances, tenure (rental units) and vacant housing remained associated with PTB. However, only tenure (high number of rentals) remained statistically significant. No associations between crime or security measures and PTB were observed.
• Small for gestational age (SGA):
  As with PTB, living in an area with high amounts of housing damage, property disorder, nuisances, rentals and vacant housing were associated with SGA. After adjusting for maternal factors, housing damage remained statistically significant. No associations between crime or security measures and SGA were observed.
• Low birthweight (LBW):
  Living in an area with more property disorder, rentals, vacancies and nuisances was associated with lower birthweight babies. Living in residential areas with more housing damage showed an enduring statistically significant link to LBW in both the unadjusted and adjusted analysis. Again, no associations between crime or security measures and LBW were observed.

Tying it all together
This study suggests a very real and meaningful relationship between the location where a woman experiences her pregnancy, and the outcomes of that pregnancy. The built environment surrounding pregnancy contributes to health disparities by way of birth outcomes. This relationship may seem obvious enough, and now it’s backed by research studies. This is by far not the only study to analyze the way in which the built environment impacts health. The physical environment is a leading determinant of individual and community-wide health, and can predict health disparities and inter-generational health. 

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