1. Risk Factors for Adverse Birth Outcomes
Joshua Blaskowski
Department of Mathematics and Statistics
GOAL
BIRTH FACTS IN THE U.S.
MAPS
Goal: To examine factors related to infants being born prematurely, being small for gestational age (SGA), and being born with a low birth weight (<2500g) in North Carolina.
Every year the North Carolina State Center for Health Statistics gathers information on all infants born in the state. This information consists of demographic information, adequacy of prenatal care, medical conditions of the mother during pregnancy, and birth outcomes.
The data used in this study consists infants born in the year 2007 with approximately n = 130,886 mother/infant dyads.
POTENTIAL RISK FACTORS
Anemia
Acute or chronic lung disease
Age of Mother
Cardiac disease
Diabetes
Drink during pregnancy
Eclampsia
Weight Gained
Genital Herpes
Hypertension, Chronic
Hypertension, Pregnancy
Marital Status
Education of Mother
Mother Race
Month Prenatal Care Began
Previous preterm/small infant
Smoker (Y/N)
Total Pregnancies (including This One)
Uterine Bleeding
Number of Prenatal Visits
Again we can see the largest risk associated with having a low birth weight infant is a mother having eclampsia (OR = 4.25) followed by having had a previous premature baby (OR = 3.96). In terms of preventable behaviors we see maternal smoking and drinking are associated with increased risk of having an infant with a low birth weight
3,957,577 babies were born in the United States in 2013.
1 in every 12 babies in the United States is born with low birthweight.
The 2013 preliminary low birthweight rate was 8.02%.
The 2013 preterm birth rate was 11.39%.
In 2007, the Institute of Medicine reported that the cost associated with premature birth in the United States was $26.2 billion each year.
Premature birth and fetal growth restriction (small for gestational age) are the two main reasons babies are born with low birthweight.
Low birth weight is defined as a birthweight of a live-born infant of less than 2,500g (5 pounds 8 ounces) regardless of gestational age.
Small for gestational age (SGA) babies are those who are smaller in size than normal for the gestational age, most commonly defined as a weight below the 10th percentile for the gestational age.
A birth is considered preterm if the infant has a gestational age less than 37 weeks.
LOGISTIC REGRESSION
To find which risk factors were most significant a stepwise logistic regression analysis was used.
Models were developed for low birthweight (<2500g), SGA (small for gestational age), and premature birth separately
Once all significant factors were found odds ratios were computed for each of the factors in the model in order to quantify the level of risk associated with each.
Maternal smoking during pregnancy is associated with the greatest risk of having an infant classified as small for gestational age (OR = 2.19).
RESULTS
DISCUSSION
Hispanic mothers have the smallest risk of having a preterm baby, low birthweight, and SGA. Black mothers have the highest risk for all three outcomes.
Smoking was a significant factor for both low birthweight and SGA but was not significant when considering factors related to pre-term birth.
Drinking during pregnancy was a significant factor for both pre-term and low birth weight, however it was not significant for SGA.
Eclampsia poses the greatest risk for having an infant prematurely, having an infant with a low birth weight, and is the second largest risk factor for SGA.
References
CDC Centers for Disease Control and Prevention
March of Dimes
North Carolina State Center for Health Statistics
Premature
SGA
North Carolina is divided into six perinatal care regions in order to coordinate health care and services to improve pregnancy outcomes . The maps above show premature birth and SGA rates for counties in NC. From the maps it is obvious that counties in Region VI has several counties with high rates of these adverse birth outcomes.
From the table above we can see that largest risk factor associated with prematurity is the mother having eclampsia (OR = 4.12) during pregnancy followed by previously giving birth to an infant prematurely (OR = 3.80). In terms of preventable risk factors, maternal drinking during pregnancy increases the odds of premature birth (OR = 1.44). Also we see that regular prenatal visits is associated with decreased risk of premature birth (OR = .90), i.e. a 10% decrease in odds per visit.
Faculty Advisor: Brant Deppa