The word "doula" comes from Greek and means "woman's servant." It referred to the women who traditionally provided support to mothers in labor.
The Doulas of North America organization (DONA) defines a modern-day doula in the following way:
A birth doula is a person trained and experienced in childbirth who provides continuous physical, emotional and informational support to the mother before, during and just after childbirth.
Some doulas only work during labor itself, but most doulas work with women before and just after the birth as well. They give emotional support and information as needed during pregnancy, provide support and encouragement during labor, and then give early post-partum and breastfeeding support.
Research has shown that having a doula during labor can help lower the risk for a cesarean, and may also help increase breastfeeding initiation rates.
Professional labor support is probably even more important for women of size because women of size tend to be subjected to more labor interventions and restrictions and have higher cesarean rates and lower breastfeeding rates than women of average size. Doulas may be one powerful way of improving outcomes among high-BMI women.
Here is the most recent research supporting the importance of more wide-spread access to doulas.
Am J Manag Care. 2014 Aug 1;20(8):e340-52. Potential benefits of increased access to doula support during childbirth. Kozhimannil KB1, Attanasio LB, Jou J, Joarnt LK, Johnson PJ, Gjerdingen DK. PMID: 25295797
...Retrospective analysis of a nationally representative survey of women who delivered a singleton baby in a US hospital in 2011- 2012 (N = 2400)...Six percent of women reported doula care during childbirth. Characteristics associated with desiring but not having doula support were black race (vs white; adjusted odds ratio [AOR] = 1.77; 95% CI,1.03-3.03), and publicly insured or uninsured (vs privately insured; AOR = 1.83, CI, 1.17-2.85; AOR = 2.01, CI, 1.07-3.77, respectively). Doula-supported women had lower odds of cesarean compared without doula support and those who desired but did not have doula support (AOR = 0.41, CI, 0.18-0.96; and AOR = 0.31, CI, 0.13-0.74). The odds of nonindicated cesarean were 80-90% lower among doula-supported women (AOR= 0.17, CI, 0.07-0.39; and AOR= 0.11, CI, 0.03-0.36)...Increasing awareness of doula care and access to support from a doula may facilitate decreases in nonindicated cesarean rates.Am J Public Health. 2013 Apr;103(4):e113-21. doi: 10.2105/AJPH.2012.301201. Epub 2013 Feb 14. Doula care, birth outcomes, and costs among Medicaid beneficiaries. Kozhimannil KB1, Hardeman RR, Attanasio LB, Blauer-Peterson C, O'Brien M. PMID: 23409910
...We calculated descriptive statistics for Medicaid-funded births nationally (from the 2009 Nationwide Inpatient Sample; n = 279,008) and births supported by doula care (n = 1079) in Minneapolis, Minnesota, in 2010 to 2012; used multivariate regression to estimate impacts of doula care; and modeled potential cost savings associated with reductions in cesarean delivery for doula-supported births. RESULTS: The cesarean rate was 22.3% among doula-supported births and 31.5% among Medicaid beneficiaries nationally. The corresponding preterm birth rates were 6.1% and 7.3%, respectively. After control for clinical and sociodemographic factors, odds of cesarean delivery were 40.9% lower for doula-supported births (adjusted odds ratio = 0.59; P < .001). Potential cost savings to Medicaid programs associated with such cesarean rate reductions are substantial but depend on states' reimbursement rates, birth volume, and current cesarean rates. CONCLUSIONS: State Medicaid programs should consider offering coverage for birth doulas to realize potential cost savings associated with reduced cesarean rates.J Midwifery Womens Health. 2013 Jul-Aug;58(4):378-82. doi: 10.1111/jmwh.12065. Epub 2013 Jul 9. Doula care supports near-universal breastfeeding initiation among diverse, low-income women. Kozhimannil KB1, Attanasio LB, Hardeman RR, O'Brien M. PMID: 23837663
...We compared breastfeeding initiation rates (means and 95% confidence intervals) for 1069 women who received doula care from Everyday Miracles, a Minnesota-based organization that employs a diverse group of certified doulas, to a state-based sample of women with Medicaid coverage who gave birth in 2009 or 2010 and participated in the Minnesota Pregnancy Risk Assessment Monitoring System survey (weighted n = 51,721). RESULTS: Women who had doula-supported births had near-universal breastfeeding initiation (97.9%), compared with 80.8% of the general Medicaid population. Among African American women, 92.7% of those with doula support initiated breastfeeding, compared with 70.3% of the general Medicaid population. DISCUSSION: These results suggest that access to culturally appropriate doula care may facilitate higher rates of breastfeeding initiation. When supported in their nonmedical needs by birth doulas, the diverse, low-income patients of midwives and other maternity care providers may have a greater likelihood of initiating breastfeeding and experiencing the maternal and infant health benefits associated with breastfeeding.Cochrane Database Syst Rev. 2013 Jul 15;7:CD003766. [Epub ahead of print] Continuous support for women during childbirth. Hodnett ED1, Gates S, Hofmeyr GJ, Sakala C. PMID: 23857334
BACKGROUND: Historically, women have been attended and supported by other women during labour. However, in hospitals worldwide,continuous support during labour has become the exception rather than the routine...Twenty-two trials involving 15,288 women met inclusion criteria and provided usable outcome data...Women allocated to continuous support were more likely to have a spontaneous vaginal birth (RR 1.08, 95% confidence interval (CI) 1.04 to 1.12) and less likely to have intrapartum analgesia (RR 0.90, 95% CI 0.84 to 0.96) or to report dissatisfaction (RR 0.69, 95% CI 0.59 to 0.79). In addition, their labours were shorter (MD -0.58 hours, 95% CI -0.85 to -0.31), they were less likely to have a caesarean (RR 0.78, 95% CI 0.67 to 0.91) or instrumental vaginal birth (fixed-effect, RR 0.90, 95% CI 0.85 to 0.96), regional analgesia (RR 0.93, 95% CI 0.88 to 0.99), or a baby with a low five-minute Apgar score (fixed-effect, RR 0.69, 95% CI 0.50 to 0.95)...AUTHORS' CONCLUSIONS: Continuous support during labour has clinically meaningful benefits for women and infants and no known harm. All women should have support throughout labour and birth.