Complex sentence: Humorously insisting that her children must not be born Yankees, Ellen went to relatives in Georgia for Margaret's birth in 1886 and Jessie's in 1887--but Eleanor was born in Connecticut in 1889, while Wilson was teaching at Wesleyan University.
Split into simpler sentences: Humorously insisting that her own children must not be born Yankees, she went to relatives in Georgia for the birth of Margaret in 1886 and Jessie in 1887. Eleanor, however, was born in Connecticut in 1889, while Wilson was teaching at Wesleyan University.