Table 2.

Measurement, timing and statistical power considerations for primary and secondary outcomes

Outcome	Measurement	Timing	Minimum detectable effects*
Primary outcomes
Severe maternal morbidity	Modified Centers for Disease Control and Prevention algorithm	Delivery through 42 days and through 365 days postpartum	Assuming a baseline rate of 5%, the largest detectable difference is 1.21% point
Person-reported health and wellbeing	Mothers Autonomy in Decision-Making scale [41] and Mothers On Respect index [42]	Pregnancy through 365 days postpartum	Assuming a baseline score of 35, the minimum detectable difference in score of BIPOC beneficiaries versus not is 3.4 points in the score
Evidence-based postpartum care for chronic conditions: treatment for hypertension	Follow-up visit within 10 days for blood pressure evaluation and screening (source ACOG [43]) or outpatient visit with first position diagnosis code related to hypertension or outpatient visit with cardiologist	7–365 days postpartum	Among NHB women with hypertension, assuming a prevalence rate of 21.4%, bringing sample size down to 50 883. Assuming a baseline treatment rate of 18% [44], the largest detectable difference is 4.93% point
Evidence-based postpartum care for chronic conditions: treatment for mental health conditions (excluding substance use disorders)	Screening for depression during the postpartum period (source: ACOG [45, 46]) in either maternal or infant claims [47] or outpatient visit with first position diagnosis code for a mental health disorder or outpatient visit with mental health specialist	7–365 days postpartum	Among NHB women with MH disorder, assuming a prevalence rate of 21%, bringing the sample size to 49 932. Assuming a baseline treatment rate of 80%, the largest detectable difference is 4.88% point
Evidence-based postpartum care for chronic conditions: treatment for substance use disorders	Use of medication for opioid use disorder (Source: ACOG [48]) or outpatient visit with first position diagnosis code for substance use disorder or outpatient visit with substance use disorder specialist	7–365 days postpartum	Among NHB women with SUD disorder, assuming a prevalence rate of 10%, bringing the sample size to 23 777. Assuming a baseline treatment rate of 60%, the largest detectable difference is 8.79% point
Secondary outcomes
All-cause mortality	Number of postpartum persons who die of any cause per 100 000 births	Delivery through 365 days postpartum	No statistical models will be applied
Participant experiences of discrimination or medical racism: racial or socioeconomic discrimination	Everyday Discrimination Scale	Delivery through 365 days postpartum	Assuming a baseline score of 3, the minimum detectable difference in score of BIPOC participants versus not is 0.14 point in the score

*Detectable effect sizes were calculated at a significance level of 0.05 and a power of 0.8, assuming at least 1% of the population of interest (i.e. non-Hispanic Black) engages with doula care over a period of 4 years, with a total sample size of 237 700. The total sample size was inferred from the number of non-Hispanic Black persons with deliveries paid for by Medicaid in 2020 among the six states, multiplied by four. If a greater proportion of the population uses doula services, we will be powered to detect even smaller effect sizes.