Establishing the health effects of sugar-sweetened beverage (SSB) taxes has been tricky. It takes years for diabetes to develop, and Berkeley only passed its first-in-the-nation SSB tax in 2015. Yet, evidence has mounted that SSB taxes reduce SSB sales and sugar intake.

We study the health effects of SSB taxes during pregnancy, when nutrition can have long-lasting impacts. Gestational diabetes, for example, leads to a 7-fold ↑ risk of the mother getting type 2 diabetes.

Using data from 5+ million US births from 2013-19, we study changes in risk of gestational diabetes and gestational weight gain following SSB taxes as well as several secondary outcomes for mothers and infants.

We compare changes in outcomes for pregnant women in 5 US cities with SSB taxes (Berkeley, Philly, Oakland, San Fran, Seattle) vs. pregnant women in other large, urban US cities, using a Callaway-Sant'Anna difference-in-differences approach.

We find that the SSB taxes led to: 1) ↓ risk of GDM by 41% (-2.2 percentage points) 2) ↓ gestational weight gain by 7.9% (-0.2 std. dev) 3) ↓ risk of small-for-gestational-age babies by 39.1% (-4.3 percentage points)

Some of the largest perinatal benefits of SSB taxes occurred in Philly, consistent with evidence (from @cawley_john @RobertoCA @DrBleich and others) that Philly's SSB tax led to a particularly large decline in SSB sales and consumption.

We also found interesting differences in the impacts of SSB taxes across subgroups, although we didn't come away with clear conclusions about whether the taxes reduced the stark disparities that exist in perinatal health. Much more work is needed.

This is the first study I know of focused on the perinatal effects of SSB taxes, and it makes the case that SSB taxes can provide important health benefits to women and children.

Thanks to @NICHD_NIH and @NIDDKgov for their support. cc @UCSF_IHPS @UCSF_Epibiostat @UCSFFamilyMed @UCSF_ObGynRS @ucsfcvp @ChangeLabWorks @HealthyFA @NOPRENnetwork @drdeancommxn @RobertLustigMD @HilarySeligman @skaplan92 @knoxmecon @JenFalbe @AnnaGrummon @marionnestle @ShuWenNg

@justinswhite @k_andreujackson @DrRitaHamad @karasekd Thank you for publishing this with us!