The baptism records of the First Congregational Church of Webster Groves list two infant baptisms:
Pg. 1, #22 - Charles Henry Prehn, born 17 Sep 1871 and baptized 01 Oct 1871
Pg. 1 #23 - John Frederick Prehn born 17 Sep 1871 and baptized 01 Oct 1871
The parents for both children are listed as Henry & Johanna Prehn. So we know that Johanna gave birth to twins. The only newspaper reference to Johanna's death is found in the "Missouri Republican," 24 Sep 1871 issue (pg. 2). However, that is just one sentence that merely says "Johanna beloved wife of Henry" died.
The mystery is that we don't know what happened to the boys. They simply vanish. They aren't living in Henry Prehn's household in the 1880 census. Henry remarried in 1873. In 1880 he's listed with his two children (14 and 12) from his marriage to Johanna and four children from his second marriage. None of which are the boys listed above.
At the time of her death, Johanna had a 4 year old son and a 2 year old daughter. The most likely scenario is that Henry felt he could take care of these two toddlers, but couldn't take care of twins (or triplets) so decided to give them up for adoption. There was an orphange in Webster Groves called St. Louis Protestant Orphans' Asylum. I found that the Western Historical Manuscript Collection at the University of Missouri had microfilm copies of their records. I checked roll #5 which contained the record of admissions and departures for that time period...nothing. Of course that doesn't mean they weren't given to another orphanage. Henry's will (probated 10 Dec 1913) makes no mention of these boys.
1. Was William John Prehn a child of Henry and Johanna? If so...why wasn't he baptized at the same time as the other two boys? If his age is accurate in the death register, he was born about the 20th of Sep (3 days after the other boys)...so not likely to be Johanna's. The only other Prehn living is Webster Grove was Henry's brother, John Prehn. I don't think this infant could be John's because his wife gave birth to a daughter in April of 1872. Although it's not impossible to have only a six and one half month separation between births, it seems unlikely.
2. If Henry was going to give the boys up for adoption, why have them baptized? But mostly...where did the boys go? They aren't listed as dying or being buried anywhere in the Webster Grove area.It just remains a mystery...