How many moms are diagnosed with PPD/PPA per year in the USA? How many in CA? And how many of them are on Medicaid?
Research studies generally report on prevalence rates (i.e. proportion of people who have some disease at any given time), rather than the actual number of people. This is just because of the way that the studies are designed. So, we kind of have to extrapolate/estimate the number of people. But, whether looking at prevalence or actual numbers, PPD/PPA stands out as a major public health concern.
There have been a few research studies on the prevalence of PPD (i.e. proportion of moms who develop PPD in any given year). Estimates vary pretty widely, but it is generally accepted that ~12 percent of mothers experience PPD worldwide (Woody, Ferrari, Siskind, Whiteford, & Harris, 2017). More popular news outlets will usually just say something like "approximately 1 in 5 mothers.
Women low- and middle-income countries are more likely to experience PPD than those from high-income countries (~13% for lower-income, ~11% higher income) (Woody et al., 2017).
According to the CDC, about 13% of mothers in the US experienced PPD symptoms in 2015 (http://www.cdc.gov/prams/pramstat/index.html). This was from a nationally representative sample of women from 27 states (although not including California). This is the most recent report of this nature.
The CDC did not report on SES (social-economic status) per se, but rates did differ by age (younger mothers more likely to experience PPD than older mothers), race/ethnicity (minority mothers more likely to experience PPD than white mothers), education level (mothers without college more likely to experience PPD than mothers with college), marital status (unmarried mothers more likely to experience PPD than unmarried mothers), and stressful events the year before birth (a greater number of stressful life events is associated with greater likelihood of PPD). All of these factors are likely more common in women with lower SES. Other factors associated with a greater prevalence of PPD are preterm birth, low birth weight, and admission of the infant into the NICU. (Ko, Rockhill, Tong, Morrow & Farr, 2017) (http://dx.doi.org/10.15585/mmwr.mm6606a1).
Research studies don’t estimate actual numbers (just prevalence rates or percentages). But, we can think about approximate numbers based on these rates based on the CDC’s reports on births (https://www.cdc.gov/nchs/data/nvsr/nvsr67/nvsr67_08-508.pdf). These numbers are from 2017 since it doesn't look like anything from 2018 has been published yet.
3,855,500 births in the US --> ~462,660 women with PPD symptoms in 2017
471,658 births in California --> ~56,599 women with PPD symptoms in 201
1,657,865 births paid for by Medicaid in the US --> ~215,522 women with PPD symptoms on Medicaid in 2017
Almost half of million moms are diagnosed with PPD/PPA in the United States. Another half of million if not, even more, are suffering from PPD/PPA and have not been diagnosed yet or at all.
Ko JY, Rockhill KM, Tong VT, Morrow B, Farr SL. Trends in Postpartum Depressive Symptoms — 27 States, 2004, 2008, and 2012. MMWR Morb Mortal Wkly Rep 2017;66:153–158. DOI: http://dx.doi.org/10.15585/mmwr.mm6606a1
Woody, C. A., Ferrari, A. J., Siskind, D. J., Whiteford, H. A., & Harris, M. G. (2017). A systematic review and meta-regression of the prevalence and incidence of perinatal depression. Journal of Affective Disorders, 219, 86–92. https://doi.org/10.1016/j.jad.2017.05.003