North Carolina.
The research team were all female except the data/statistics expert. Two family medicine doctors, two endocrinologists and a research nurse.
I can't access the full text. If all the hormones were administered by patch (the estradiol was) then there's a clear statement that patch meds don't turn up in breast milk. I hope that's right.
It is true that in agricultural societies, it might be usual for a grandmother to feed a baby left with her so that the mother can return to work. I don't in principle object to the idea of women feeding each others' babies, though commercial wetnursing is usually exploitative.
So I can see how this bunch reassured themselves that this kind of recreational fetishism was OK. Shame on them.