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Pre-pregnancy Stress May Lead to Babies with Low Birth Weight

Adapted from “Diurnal salivary cortisol patterns prior to pregnancy predict infant birth weight.” published in the journal Health Psychology in June 2016.

For a woman, the stress of infertility has been compared to having a diagnosis of cancer or HIV. Full-time employment, hostile mood, depression, and high anxiety have been shown to correlate with retrieval of fewer eggs and IVF failure.

Stress shifts blood supply to the heart, brain, and muscles from “nonessential” organs, such as the ovary. Stress increases the levels of circulating stress hormones (i.e., cortisol) resulting in vasoconstriction also reducing blood flow to the ovary.

In addition, previous studies have shown that elevated maternal psychological stress during pregnancy with accompanying changes in stress hormones have a negative impact on fetal growth and subsequent development that extends into adulthood.

A new study from the University of California Los Angeles provides the first evidence that a woman’s biological stress profile (particularly elevated levels of stress hormone cortisol) before she becomes pregnant may lead to lower birth weight babies.

Each year, more than 300,000 babies with a low birth weight (less than five-and-a-half pounds) are born in the United States. These babies have above average risk for infant mortality and for health abnormalities throughout their lives, including cardiovascular and metabolic disorders.

In the study, cortisol levels before and during pregnancy were measured in a diverse community sample of 142 women from Los Angeles, Washington, D.C., Baltimore, Lake County, Illinois, and eastern North Carolina.

Normally, cortisol levels are high in the morning and then decline as the day progresses. The new study showed that majority of lower-weight babies came from mothers whose high cortisol levels remained the same throughout the day.

The effects of elevated stress levels can be both immediate (elevated cortisol levels reduce blood flow to the fetus) and longer-lasting, influencing the child’s response to stress later in life.

The researchers found that the mothers' stresses came from finances, relationships within the family, and neighborhood issues. Major life events such as death in the family, racism, and interpersonal violence were also noted.

The study findings imply that women should treat depression, evaluate and treat stress, be sure they are in a healthy relationship, be physically active, and gather family support. All of the things that create an optimal pregnancy and healthy life for the mother should be done before attempting pregnancy.

January 2017


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