The American Association of Birth Centers (AABC) promotes and supports birth centers as safe, sensitive, and cost-effective care-taking place in an environment with minimal intervention.1 The model of care in the hospital setting includes care for normal labor, birth, and continuous risk screening that is consistent with the best available evidence for normal physiologic labor and birth, and with national standards for midwifery and birth center care.1 This in-hospital model may also be called an Alongside Midwifery Unit (AMU).1 More common in the United Kingdom, an AMU is a place for normal, physiologic labor, birth, and immediate postpartum and neonatal course within and alongside a hospital setting. Any condition or intervention that falls outside of this parameter requires transfer to the acute care obstetrical or neonatal unit.1,2 Currently, in the United States, there are 4 Commission for the Accreditation of Birth Centers (CABC)–accredited Alongside Units.2 This column reviews the history of the birth center model of care, the development of AMUs, and the evidence for dedicated protected space for normal physiologic birth within hospitals.
Maternity care in the 20th century was marked by the change in primary birth setting of home to hospital, from 5% at the beginning of the century to 98% in the hospital by the end.2–5 Substantial reductions in maternal and infant mortality rates were not appreciable until the second half of the century owing to broad-spectrum antibiotics and blood banking; yet, rates of routine intervention (continuous electronic fetal monitoring, intravenous catheters, limited maternal mobility, epidurals, no oral intake, episiotomies, forceps, and cesarean births) increased significantly.2–5 A central focus of the women's health movement of the 1960s and 1970s was on changing hospital childbirth practices and the medicalization of a normal life event.6 Women desired more control over the birth experience, choice of provider, place, inclusion of partner support in the labor room, options for coping, and support for breastfeeding.2–7
A growing and highly public consumer criticism of the medical management of childbirth developed.7 In response to this critique of the increasing medicalization of birth, the 1970s and 1980s witnessed a resurgence of midwifery, homebirth, and freestanding birth centers.2,8–10 Birth centers did not receive national attention until the Maternity Center Association (MCA) opened its birth center in New York City in 1975, a demonstration project for safe, out-of-hospital, family-centered maternity care.7 The next decade would see the growth of an additional 160 birth centers opening.7 At the crux of the birth center movement is the notion that maternity services be responsive to family desires, allowing the childbearing family the opportunity to regulate their birth environment.8
Birth centers may be freestanding or in-hospital.9 In 1983, AABC was established and set standards for freestanding birthing centers leading to specific certification requirements.9 In 1989, the safety of birth centers was recognized in a study published in The New England Journal of Medicine.10 A replication of the study conducted by AABC was published in 2013 with similar high-quality, safe outcomes, noting the durability of the model of care.11 The study reported a cesarean rate of 6%, compared with an expected 25% for similarly low-risk women in a hospital setting.11 Neonatal outcomes were on par with hospital settings.11
In addition to these positive clinical outcomes, birth centers provide the benefit of reduced costs.11 Birth centers consistently display charges for care for a normal birth that averaged up to 50% less than charges for an uncomplicated birth in the hospital. Beyond the safety and cost-efficiency, most recent studies display the equity of outcomes in birth center models, with no variations in experience of care, cesarean rates, or breastfeeding.12 Hence, not only are the outcomes durable but they are also both equitable and cost-efficient.
Nationally, most labor and birth units take care of birthing persons, regardless of risk. However, the research evidence does not support a model where all rooms in a labor and birth unit support natural physiologic birth while also providing the capability to care for the high-complexity/high-risk birthing people within the same space. Rather, the evidence shows that protected space has superior outcomes when compared with universal rooms that accommodate all needs, regardless of complexity.12,13 Dedicated space provides a layer of protection to the process of normal physiologic birth, reduces overuse of interventions, and unwarranted variations in care. For example, nationally, birth centers report a 15% transfer rate and a 6% cesarean birth rate. This compares dramatically with a national, low-risk, first-time cesarean rate also referred to as the nulliparous, singleton, term, vertex (NTSV) cesarean rate of 7.9% to 69%, depending on facility.12,13 There are 2 systematic reviews in the Cochrane database that compare hospital settings for birth with in-hospital birth centers or Alongside Units, revealing that the intervention rate, use of pain medications, greater mobility in labor, and greater satisfaction with care were noted in the in-hospital birth center (or protected space for normal physiologic birth).12,13 This reflects the triple aim.
The risk of intervention and transfer is significantly reduced through care pathways that are supported by criteria based upon current evidence.14 These encompass robust antenatal risk assessment of suitability; admission triage by experienced midwives; and one-to-one midwifery care in a nonclinical environment.14 AMUs provide birthing individuals within the low-risk category, the choice of an Alongside Unit model of care. Outcomes are improved and the experience of birthing families improved by reducing the likelihood of intervention and the associated risk and cost of instrumental births and surgical delivery.1,12–14 In addition there is a reduced length of hospital stay, resulting in decreased cost and the impact of separation for birthing individuals and their families.1,12–14
Interprofessional teams may develop their skills, confidence, and competence in spontaneous vaginal birth as AMUs enhance the culture of normality within the wider maternity unit and community by reinforcing and improving knowledge and skills base.14 Trials of nonclinical healthcare interventions show that approaches that prioritize positive human relationships promote respectful and collaborative multidisciplinary teamwork and address clinician beliefs and attitudes, and women's fear of labor pain and of poor quality of care, might be effective in reducing cesarean birth or increasing physiologic labor and birth.14 These include labor companionship, continuity of care, midwife-led units, antenatal education, training, and implementation of evidence-based guidelines at the point of care.12–14
Childbirth is the most common reason for hospitalization in the United States.2 Growing evidence for midwifery-led, in-hospital birth centers with low-risk, childbearing women reaches the triple aim: reduced cost, improved outcomes, and high patient satisfaction. At a time when conventional maternity models are failing women, embracing models of care that have demonstrated equity and value is critical. An in-hospital birthing center or AMU can support low-risk women in having a safe and satisfying birth experience, improve outcomes, and decrease cost.1,12–17
—Elisabeth Howard, PhD, CNM, FACNM
Director of Midwifery
Women and Infants Hospital
Obstetrics and Gynecology (Clinical)
Alpert Medical School, Brown University
Providence, Rhode Island
Linda Nanni, MSN, CNM, FACNM
Clinical Teaching Associate
Warren Alpert Medical School
Providence, Rhode Island
1. American Association of Birth Centers. Birthcenters.org
. Accessed January 1, 2022.
2. Caughey AB, Cheyney M. Home and birth center birth in the United States. Obstet Gynecol. 2019;133(5):1033–1050.
3. Davis-Floyd RE. The technocratic body: American childbirth as cultural expression. Soc Sci Med. 1994;38(8):1125–1140.
4. Arms S. Immaculate Deception: A New Look at Womanhood and Childbirth in America. Boston, MA: Houghton Mifflin; 1975.
5. Wainer Cohen N, Estner LJ. Silent Knife: Cesarean Prevention & Vaginal Birth After Cesarean. Granby, MA: Bergin & Garvey Publishers; 1983.
6. Nichols FH. The story of the women's health movement in the 20th century. J Obstet Gynecol Neonatal Nurs. 2000;2:56–64.
7. Rooks J. Midwifery and Childbirth in America. Philadelphia, PA: Temple University Press; 1993.
. Accessed October 1, 2020.
9. Rooks JP, Weatherby NL, Ernst EM, Stapelton S, Rosen D, Rosenfield A. Outcomes of care in birth centers: the National Birth Center Study. N Engl J Med. 1989;321(26):1804–1808.
10. Stapleton SR, Osborne C, Illuzzi J. Outcomes of care in birth centers: demonstration of a durable model. J Midwifery Womens Health. 2013;58(1):3–14.
11. Stapleton S, Wright J, Jolles DR. Improving the experience of care: results of the American Association of Birth Centers Strong Start Client Experience of Care Registry Pilot Program, 2015-2016. J Perinat Neonatal Nurs. 2020;34(1):27–37.
12. Hodnett ED, Downe S, Walsh D. Alternative versus conventional institutional settings for birth [review]. Cochrane Database Syst Rev. 2012;8(9):CD000012.
13. Sandall J, Soltani H, Gates S, Shennan A, Devane D. Midwife-led continuity models of care compared with other models of care for women during pregnancy, birth, and early parenting. Cochrane Database Syst Rev. 2016;(4):CD004667. https://www.cochrane.org/CD004667/PREG_midwife-led-continuity-models-care-compared-other-models-care-women-during-pregnancy-birth-and-early
. Accessed January 1, 2022.
14. Midwifery Unit Network. Vision, mission and values. https://www.midwiferyunitnetwork.org/vision-mission-values
. Accessed January 1, 2022.
15. Breedlove G, Rathbun L. Facility design: reimagining approaches to childbirth in hospital and birth center settings. J Perinat Neonatal Nurs. 2018;33(1):26–34.
16. Shah N. Reimagining Childbirth Facilities Design Workshop Organized by FGI [Facilities Guidelines Institute] and ACOG; April 30-May 1, 2018; Austin, TX. https://aahid.org/reimagining-childbirth-facilities-design-workshop
. Accessed January 1, 2022.
17. Avery MD, Bell AD, Corry MP, et al. Blueprint for advancing high-value maternity care through physiologic childbearing. J Perinat Educ. 2018;27(3):130–134.