Award-winning series by author and essayist Uchida Shungicu. Starting in 1993 and still ongoing, this is a frank, sex-positive look at pregnancy, childbirth, child rearing, and single motherhood, notable for tackling such issues directly at a time when such treatments were rare. Following site guidelines, the series is tagged as Erotica because it has sex in it, but if you're looking for an erotic manga per se, you'll probably want to look elsewhere.