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Reproductive and Birth Outcomes


What are reproductive and birth outcomes?

More than three million healthy babies are born annually in the United States. While most women have a normal term pregnancy and deliver a normal infant, a safe and healthy pregnancy is not experienced by all women. Certain genetic, behavioral, social and environmental factors can affect the parents' ability to conceive, carry, and deliver a healthy, full-term baby.

Our understanding of risk factors for reproductive problems has increased over the past decades. However, there is still much we donot know.To better understand the role that environmental exposures play in reproductive and infant health problems Oregon Tracking collects and displays data on reproductive and birth outcomes including preterm birth, infant deaths and birth weight.

Who is at risk?

In 2016, preterm birth affected about 1 of every 10 infants born in the United States. A developing fetus goes through important growth throughout pregnancy including in the final months and weeks. For example, the brain, lungs and liver need the final weeks of pregnancy to fully develop. Babies born very preterm (before 32 weeks) have higher rates of death and disability. Oregon tends to have a significantly lower incidence of preterm births and low birth weight babies than the national average.

Preterm birth is a leading cause of infant mortality, morbidity and long-term disability. All infants born preterm (before 37 weeks) are at risk for serious health problems. Babies born earliest are at greater risk. Studies have shown that children born preterm with very low birth weight have an increased risk of attention deficit hyperactivity disorder, cerebral palsy and intellectual disability. Preterm birth is also associated with congenital gastrointestinal defects, such as gastroschisis. Infants with very low birth weight have about 25% chance of dying in the first year of life, about 100 times higher than for normal weight infants. Other conditions include visual problems, hearing loss, infections and chronic lung diseases.

Preterm births occur at a significantly higher rate for multiple births and among non-Hispanic African-American mothers.

Preterm births and low birth weights are associated with several maternal genetic, lifestyle and environmental risk factors including:

  • Previous preterm births
  • Uterine or cervical abnormalities
  • Maternal under 18 and over 35 years old
  • Low income and education level
  • Lack of prenatal care
  • Smoking, drinking and drug use
  • Domestic violence
  • Stress
  • Body weight (underweight and overweight)
  • Short time between pregnancies
  • Exposure to air pollution
  • Exposure to drinking water contaminates

The presence of risk factors does not mean that an infant will be born preterm or low weight. Likewise, the risk of a preterm birth is not zero even if a pregnancy has no risk factors.

How to reduce risk:

Reducing risk for negative reproductive and birth outcomesremains a challenge. Causes may be complex and not always well understood. However, pregnant women can take important steps to help reduce their risk of preterm birth and improve their general health.

These steps include:

  • If you smoke, quit. For help quitting, see Oregon Tobacco Quit Line.
  • Avoid alcohol and drugs.
  • Get prenatal care as soon as you think you may be pregnant and during the pregnancy. Visit Oregon Maternal and Child Healthfor more information.
  • Seek medical attention for any warning signs or symptoms of preterm labor.
  • Talk with your doctor or other healthcare provider about the use of progesterone treatment if you had a previous preterm birth.

Reproductive and birth outcomes Oregon Environmental Public Health Program tracks:

Preterm births are when a baby is born before the 37thcompleted week of pregnancy (gestation).

Very preterm births are when a baby is born before the 32ndcompleted week of pregnancy (gestation).

Birth weight is theweight of the newborn measured immediately after birth.

Low birth weight is a birth weight of less than 5.5 pounds or 2,500 grams.

Very low birth weight is a birth weight of less than 3.3 pounds or 1,500 grams.

Infant mortality includes deaths of infants younger than 1 year of age.

Neonatal mortality includes deaths of infants younger than 28 days of age.

Post-neonatal mortality includes deaths of infants from 28 days of age to under 1 year old of age.

Perinatal mortality includes deaths after 28 weeks of gestation, stillbirths and deaths of infants younger than 7 days of age.

About the data:

Infant mortality, low birth weight and prematurity data are based on maternal residence at time of birth. This may be different than maternal residence during pregnancy and infant residence during the first year of life which affects our ability to connect these indicators to possible environmental exposures.

For the prematurity indicator, there are some uncertainties associated with gestational age estimates. The interval between the first day of the mother's last normal menstrual period and the day of birth is one method used to determine the gestational age of the newborn. However, this measurement is subject to error. Changes in reporting of the gestational age over time may affect trends in preterm birth rates. These reporting problems may occur more frequently among some group and among births with shorter gestations.

Multiple births are not included in the low birth weight and prematurity indicators. They are included in the infant mortality indicators.

Related Indicators:


For more information, visit these websites:

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