This paper examines Lobel, Dunkel-Schetter, and Scrimshaw's (1992) prospective study investigating the relationship between prenatal maternal stress and adverse pregnancy outcomes among socioeconomically disadvantaged women. The paper reviews the study's methodology, including its integration of biomedical and psychosocial data, its operationalization of stress across dimensions of life events, state anxiety, and perceived stress, and its use of structural equation modeling. It summarizes key findings — including the lack of correlation between medical risk and stress, and the association between higher stress and lower birthweight — and evaluates the study's limitations, ultimately identifying its contribution as the emergence of a biopsychosocial model of prematurity.
Medical risk factors predict only one half to two thirds of adverse pregnancy outcomes. Although elevated levels of epinephrine and norepinephrine reduce blood flow and oxygen to the fetus — which may inhibit fetal growth and precipitate labor — studies that have explored stress-related factors in low birthweight and premature delivery have produced mixed results. Researchers Lobel, Dunkel-Schetter, and Scrimshaw (1992) pursued the relationship between stress and adverse pregnancy outcomes in greater detail in their study of disadvantaged women. They examined stress more holistically than previous studies and found stronger relationships as a result.
The first major difference between this and prior studies was that Lobel et al. integrated biomedical data and psychosocial data, rather than relying on one or the other alone. They also examined the relationship between weeks of gestation and birthweight — a factor many previous researchers had overlooked. Their operationalization of the stress construct was more explicit than that of earlier researchers, and they sought to eliminate the misidentification of medical complications during pregnancy as an adverse birth outcome. The final issue with prior research they attempted to correct was the misuse of statistical tests and analyses.
The construct the researchers tested, in conjunction with biomedical data on pregnancy risk factors, was psychological stress — specifically, the response to the stimuli of life events, emotional state anxiety, and perceived stress. Although the test sample was fairly homogeneous, the researchers also examined the effects of social class, age, ethnicity, race, marital status, parity (whether this was the woman's first child), and socioeconomic status on birth outcomes.
The sample consisted of 130 women receiving prenatal care at a public clinic with a sliding pay scale, making the group predominantly low-income. Minors were excluded from the study, so participants ranged in age from 18 to 42, with an average of approximately eleven years of formal education. The sample included Latina, African American, and Anglo women; approximately eighty percent lived with the baby's father, and twenty percent received monetary support from him.
These women were interviewed and surveyed at regular intervals throughout their pregnancies. Questions addressed stress-inducing life events, their sense of control over important aspects of their lives, the level of anxiety they experienced, and related psychosocial factors.
"SEM approach linking medical risk and stress"
"Key results on stress, parity, and birthweight"
"Sample limitations and biopsychosocial model contribution"
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