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Various CNM Statistics and Studies

American Journal of Public Health Abstracts
March 1997, Vol. 87, No. 3

Interspecialty Differences in the Obstetric Care of Low-Risk Women

Objectives. This study examined differences among obstetricians, family physicians, and certified nurse-midwives in the patterns of obstetric care provided to low-risk patients.

Methods. For a random sample of Washington State obstetrician-gynecologists, family physicians, and certified nurse-midwives, records of a random sample of their low-risk patients beginning care between September 1, 1988, and August 31, 1989, were abstracted.

Results. Certified nurse-midwives were less likely to use continuous electronic fetal monitoring and had lower rates of labor induction or augmentation than physicians. Certified nurse-midwives also were less likely to use epidural anesthesia. The cesarean section rate for patients of certified nurse-midwives was 8.8% vs 13.6% for obstetricians and 15.1% for family physicians. Certified nurse-midwives used 12.2% fewer resources.

Conclusions. The low-risk patients of certified nurse-midwives in Washington State received fewer obstetrical interventions than similar patients cared for by obstetrician-gynecologists or family physicians. These differences are associated with lower cesarean section rates and less resource use. (Am J Public Health. 1997;87:344-351)

Midwives Deliver Healthy Babies With Fewer Interventions

By TAMAR LEWIN
New York Times          April 18, 1997

The University of Washington study, reported in the current issue of The American Journal of Public Health, found that certified nurse-midwives' patients had fewer Caesarean sections, received less anesthesia and had a lower rate of episiotomies and induced labor than the doctors' patients.

"There are major differences in the way physicians and nurse-midwives approach low-risk patients," said Dr. Roger A. Rosenblatt, a University of Washington professor of family medicine and principal investigator on the study.

"Nurse-midwives establish a relationship with their patients that leads to excellent outcomes with less use of medical resources. We physicians have something to learn from midwives about the approach to low-risk women."

The midwives' patients also use 12 percent fewer resources than the doctors' patients, the study found, while all three specialties achieved equally good outcomes.

While other studies over the years have reported similar findings about certain aspects of midwives' obstetric care, the University of Washington study is the first to examine differences among the three types of providers on a statewide basis.

The study is based on an analysis of the charts of 1,322 healthy low-risk patients from a random sample of all urban practitioners who deliver babies in hospitals in Washington state.

Women were excluded from the study if they had a major medical condition, a previous obstetrical complication, a serious risk factor in the current pregnancy, no obstetrical care in the first trimester or were under 18 or over 34 years old -- qualifications that excluded 53 percent of the cases screened.

One of the most striking findings in the study was the difference in the rate of Caesarean sections.

Although Caesarean sections are surgery, and must be performed by a doctor, if a midwife's patient ended up needing the procedure, the study attributed the surgery to the midwife, not to the obstetrician who performed the operation.

Still, the study found, the midwives' patients had a Caesarean section rate of 8.8 percent, compared with 13.6 percent for the obstetricians and 15.1 percent for family doctors.

"It is striking that the patients of midwives had a Caesarean section rate under 10 percent, and in some sense it gives us a target that we can consider obtainable," Rosenblatt said.

Nationally, the rate of Caesarean sections -- among low-risk and high-risk women combined -- more than doubled from 10.4 percent in 1975 to 22.7 percent in 1985. While organizations ranging from the American College of Obstetricians and Gynecologists to the Centers for Disease Control and Prevention have campaigned, with some success, for a reduction in the number of Caesarean sections, the national rate in 1995 was still 20.5 percent. Within the United States, the West has historically had the lowest rate, while the South has had the highest.

While midwives deliver the majority of babies in some European countries, including Britain, Rosenblatt said, they attend only about one in 20 births in the United States. He suggested that the training and orientation of those providing the obstetric care in this country might be a major factor in the high rate of Caesarean sections.

H.M.O.'s vs. Midwives

To the Editor:

Re "Midwives Deliver Healthy Babies With Fewer Interventions" (news article, April 18):

While I am pleased that you brought the University of Washington study to the attention of a national audience, I am disappointed that you omitted one of the key points the study made.

While Dr. Roger A. Rosenblatt, the principal investigator on the study, was quoted as saying that nurse-midwives' approach has significant advantages for patients, his study also recommended that health care policy increase the proportion of births attended by nurse-midwives.

This is a divisive issue in the competitive world of managed care. Many health maintenance organizations are controlled by physicians and deny women access to nurse-midwifery care. So while it is true, as Dr. Rosenblatt suggests, that physicians can learn something from midwives, it is important to stress the differences between nurse-midwifery and obstetrics and to inform women of the barriers that separate them from certified nurse-midwife care.

STACEY CURNOW
New Haven, April 22, 1997

[from ob-gyn-l]

Hmm, this is interesting. I don't find it surprising, however, that patients who see midwives end up with less intervention--patients who choose to see midwives often do so for just that reason. Of course there are fewer epidurals and inductions. I wonder how that affects the C-section rate too--less use of continuous fetal monitoring must be a consideration. All in all, I think this would be a much more interesting study if the patients were randomized to each provider (I'd like to see that get past an IRB).

It's been done. I'll try to remember to look up the reference at home tonight, but it was ca. 1990 in California. Patients were randomized to midwives or the OB staff. For patients of comparable risk and other baseline characteristics, midwives did less of every intervention measured, had similar outcomes, and had faster 1st and 2nd stages to boot.

Chambliss LR, Daly C, Medearis AL, Amews M, Kayne M, Paul R. The role of selection bias in comparing cesarean birth rates between physician and midwifery management. Obstet Gynecol 1992; 80:161-165.

My last practice was at an HMO where CNMs triaged all patients entering the L&D unit, independently managed all low-risk women, and co-managed most complicated patients. We did not do any prenatal care (due to union issues with NPs, limited space for providers in clinic, and poor support for CNM inclusion by the MDs), so we met all of these women for the first time when they were in labor. These were not women choosing CNM care. They just happened to have that kind of insurance. Since the CNM covering L&D frequently was responsible for the management of many laboring women (up to 7 at times), the midwife did not provide continuous labor support. Nonetheless, our epidural anesthesia rate, C/S rate, and rate of other interventions was lower than it presently is, now that the midwifery service has been greatly reduced by the hospital. Discussions with RNs still working at the hospital lead me to believe that the management style (particularly at night) has changed substantially, contributing to the increased rate of interventions.

Someone referred to a study on midwife vs. physician care done in California in the early 1990s. I believe he is probably referring to Butler, et al., "Supportive nurse-midwife care is associated with a reduced incidence of cesarean section," Am J Ob Gyn 1993:168:1407-13. Unfortunately this was not a prospective randomized trial but rather a retrospective cohort study that compared about 3500 physician-managed women with about 1000 CNM-managed women at a tertiary hospital, attempting to select just low-risk women. Because of the study's retrospective nature, there are a lot of issues around potential bias, but it is thought-provoking. Women cared for by CNMs had 0.71 risk of C-section compared to MD patients. Epidural use was a possible confounder as CNM patients had about 1/2 the rate of epidural use that MD patients did (23% vs. 42%), and it's a little unclear to me how adjusting for this affected the C-S risk issue.

Women With Low-Risk Pregnancies Receive Fewer Obstetrical Interventions When Cared For By Midwives, Compared To Women Attended By Physicians

Low-risk patients who choose nurse midwives for their obstetrical care have fewer Caesarean sections, receive less anesthesia, have a much lower rate of episiotomy and incur less expense, compared to similar women who choose physicians for their care. At the same time, obstetricians, family physicians and nurse midwives all achieve excellent results.

These are the conclusions of a University of Washington study reported in the current issue of the American Journal of Public Health.

"Nurse midwives establish a relationship with their patients that leads to excellent outcomes with less use of medical resources," said Dr. Roger A. Rosenblatt, UW professor of family medicine and principal investigator on the study. "Pregnancy is the most common reason that women spend time in hospitals, and there are major differences in the way physicians and nurse midwives approach low-risk patients."

The researchers took a random sample of all the urban practitioners in Washington state who deliver babies in hospitals: nurse midwives, family doctors, and obstetricians. They then took a random sample of those practitioners' low-risk patients, eventually analyzing 1,322 medical charts for more than 1,000 variables, covering mothers' and babies' status prenatally and during labor and birth.

The study found that the patients of certified nurse-midwives were less likely to receive continuous fetal monitoring or to have their labors induced or augmented. They were also less likely to receive epidural anesthesia. Overall, patients of midwives used 12 percent fewer resources than patients of physicians. Rosenblatt noted that midwives account for only 4 percent of deliveries in this country; they deliver the majority of babies in many countries, including Britain.

The Caesarean-section rate for patients of certified nurse midwives was 8.8 percent, compared to 13.6 percent for obstetricians and 15.1 percent for family physicians. "We used an 'intention-to-treat' protocol," explained Rosenblatt. "For example, if the patient of a midwife ended up needing a C-section, the procedure was attributed to the midwife, not to the obstetrician who performed the surgery."

The study found little difference between the practice patterns of the two groups of physicians. Obstetricians and family physicians seem to be very similar in their approaches to low-risk pregnant women.

"The major limitation of our study was that women chose their own provider, rather than being randomly allocated to different types of care," Rosenblatt acknowledged. "But in the United States, patient choice is very important. The characteristics of the women as well as the practice style of the provider likely influenced the type of care received. But the study showed that in some patients, it is possible to achieve lower rates of obstetrical intervention by adding midwives to the provider mix.

"This was not a study of quality of care, but of cost and outcome," said Rosenblatt. "However, we found that labor and delivery are incredibly safe in the state of Washington. There were no neonatal deaths, and the five-minute Apgar scores (a numerical assessment of newborn status five minutes after birth) were very high.

"We hope that this study sparks discussions of less intrusive styles of obstetric care, even among nurse midwives," he said. "Most of them worked in sophisticated urban hospitals, and half of their patients were given continuous fetal monitoring, even though earlier studies have shown that intermittent monitoring is just as effective."

The definition of low risk excluded 53 percent of pregnancies. Women were excluded from the study if they had a major medical condition, a previous obstetrical complication, a serious risk factor in the current pregnancy, no obstetrical care in the first trimester, or were under 18 or over 34 years old.

The study was funded by the Agency for Health Care Policy and Research. Co-investigators are Drs. Sharon A. Dobie, L. Gary Hart, Ronald Schneeweiss and Michael J. Pirani of the UW Department of Family Medicine; Dr. Thomas J. Benedetti of the UW Department of Obstetrics and Gynecology; Dr. Edward B. Perrin of the UW Department of Health Services; Dr. Debra Gould of the University of Rochester Department of Family Medicine; and Dr. Tina R. Raine of the Georgetown University Department of Obstetrics and Gynecology.