July 28, 2011 — Summary of "Preventing Low Birthweight: 25 years, Prenatal Risk, and the Failure to Reinvent Prenatal Care," Krans/Davis, American Journal of Obstetrics and Gynecology, June 2011.
Last year marked the 25th anniversary of Preventing Low Birthweight, an Institute of Medicine policy statement that addressed low birthweight (LBW), the most common cause of infant morbidity and mortality and an issue that has far-reaching social and economic implications. Hospitalization of LBW infants costs about $6 billion annually and represents about 50% of the costs for overall infant hospitalizations. LBW infants are at a higher risk of neurodevelopment deficits and prolonged illness.
After IOM's policy statement was released, lawmakers moved to expand prenatal care services, particularly for low-income pregnant women, who are at a higher risk for adverse birth outcomes. Medicaid eligibility was granted for an additional 14.6 million women with the intention of reducing LBW infants, but no reduction in LBW occurred, and the rate of LBW infants actually increased. The expansion of Medicaid eligibility for pregnant women was a "well-intentioned but ultimately misguided effort to expand a health care model without appropriately revising its content," Elizabeth Krans of the University of Michigan's Department of Obstetrics and Gynecology and Matthew Davis of the departments of Internal Medicine and Pediatrics at the university write. A flexible prenatal care model that is tailored to patient's risk level is needed, but policy makers have struggled to expand such models. Krans and Davis look at Preventing Low Birthweight and its effect it on legislation and policy since 1985.
LBW in the 1980s
The rate of LBW had been declining steadily since the mid-1960s until it plateaued at 6.8% between 1980 and 1983. The IOM Committee to Study the Prevention of Low Birthweight formed in 1982 and met for three years to review the cause, impact and cost of LBW and to make policy recommendations seeking to reduce the incidence of LBW. The IOM concluded that expanding prenatal care services would be an efficient and cost-effective way to decrease the rate of LBW and recommended investment in resources to improve insufficient Medicaid funding, a shortage of obstetricians and the lack of prenatal care services for low-income communities. They estimated that every $1 spent on prenatal care services would ultimately save $3.38 by reducing the number of LBW infants.
Several legislative initiatives expanded Medicaid eligibility for pregnant women in the wake of the IOM report. The proportion of pregnant women covered by Medicaid jumped from 17% in 1985 to 35% in 1998. Overall, first trimester prenatal care utilization rose from 76.2% in 1985 to 82% in 2007; rates for black women jumped from 61.5% in 1985 to 75% in 2007. However, the rate of LBW rose from 6.8% in 1983 to 8.2% in 2007.
Causes of Disconnect
The conclusions reached by the IOM committee in Preventing Low Birthweight were based on the secondary analyses of large databases of vital statistics and limited prenatal care program evaluations. Databases often record the number of prenatal visits, but fail to note the content, quality or context of the appointment. The prenatal care programs IOM examined were designed to target a particular patient population at risk for poor pregnancy outcomes. The studies were not randomized, had limited sample sizes, and typically came from health maintenance organizations, prematurity prevention projects, and maternal and child health programs.
The IOM committee explicitly articulated the inherent limitations to their data, such as selection bias, a lack of qualitative assessments, difficulty in controlling for confounding and problems with the validity of data sources and noted that these presented challenges in analyzing prenatal care. However, "these methodologic caveats were largely ignored in the policy write-ups and roll-out" in the wake of the report.
Important IOM Report Recommendations Not Followed
Preventing Low Birthweight also called for revising prenatal care to incorporate an assessment of maternal and fetal risk to "manage a wider range of patient problems and risk factors." The authors of this analysis state that it is ironic that this is the recommendation that was largely ignored because a flexible, risk-appropriate model of prenatal care could have a positive impact on reducing LBW. The IOM committee recognized that women newly enrolled in Medicaid prenatal care services, including other women at risk of poor birth outcomes, could need more frequent visits and more specialized care than women with fewer risks. Women at low-risk for adverse pregnancy outcomes could have visits less frequently, which would result in a flexible, risk-appropriate model of prenatal care.
In response, the U.S. Public Health Service in 1986 formed the Expert Panel on the Content of Prenatal Care, which released a publication titled "Caring for Our Future: The Content of Prenatal Care," which outlined evidence-based guidelines on prenatal care content, timing and frequency. The guidelines emphasized the importance of early and continuing risk assessment, health promotion, and medical and psychosocial interventions and follow-up care. The report calls for dividing women into high- and low-risk categories to allow physicians to tailor prenatal care to meet the patient's risk level. The panel said women with medical and psychosocial risk factors would need more frequent and intensive visits, involvement with case and social workers, and other outreach services. Low-risk women would have a reduced-frequency schedule depending on whether they have previously given birth, according to the panel. The change marked a shift in emphasis to the first trimester and brought the focus to content and objectives rather than just counting the number of visits.
Yet, these guidelines are largely ignored and most women in the U.S. today continue to receive the same model of prenatal care as they would have in 1985. Although the IOM report led to increased utilization of prenatal care, the model of care delivery was largely unchanged. For example, in 2004, just 17% of health care providers reported using a reduced-frequency schedule for low-risk patients, even though more than 71% said they believed they could give effective prenatal care to low-risk patients by using the model. About 30% of women received at least two more prenatal care visits than the American College of Obstetricians and Gynecologists recommended regardless of risk status. Overutilization can affect access to care and costs by draining health care resources and preventing high-risk women from benefitting from high-intensity care.
Prenatal Care in the Future
ACOG, the World Health Organization and the Institute for Clinical Systems Improvement all support a comprehensive risk assessment in the first obstetric visit and say subsequent visit frequency should be based on the needs of individual patients. Difficulties in accurately defining, assessing and addressing maternal and fetal risk are barriers to implementing the assessment. Risk can be divided into three categories: medical, psychosocial and low-risk. An accurate screening tool has not been developed, but transvaginal cervical length sonography and the fetal fibronectin test and other emerging tools have the potential to "create a risk scoring system with unprecedented predictive value for preterm birth and LBW," according to Krans and Davis. Alternative models of prenatal care to address identified risk factors also are being developed and evaluated. Home visitation, case management, telemedicine and group prenatal care all have shown particular promise for women with high-risk pregnancies. Reduced-frequency schedules for women with low-risk pregnancies have been celebrated for demonstrating equivalent maternal and fetal outcomes compared with traditional schedules.
The findings of Preventing Low Birthweight "led to expanded but undifferentiated coverage for pregnant women, as "[u]niversal prenatal care ... was extended to a heterogeneous group of patients with a variety of medical and psychosocial risk factors," Krans and Davis write. At the same time, the policy statement's recommendations to revise the prenatal care model by basing care plans on patient risk went unheeded in favor of delivering one model of care to a variety of patients. Regardless, the policy statement resulted in expanding prenatal care, which "provides women with important screening, testing, monitoring, education and counseling that are necessary for healthy maternal and fetal outcomes," Krans and Davis write. However, the challenge today remains to "transform prenatal care from a universal vehicle to a risk-appropriate intervention," Krans and Davis conclude.