Remember in high school when your teacher showed you horror porn (aka, "The Miracle of Life")? A great scare tactic for both sexual intercourse and ever becoming an adult, because as a 14-year-old you figured anyone who would call that mass of blood and crying a "miracle" was someone you did not want to be.
Well, to put it bluntly, humans have it easy.
|For one, you don't look like this.|
Caecilians (which are a weird amphibian group that look like legless, massively-uglier salamanders with a permanent sad face) have two life strategies which both really suck for mom. Version A: live birth, with several embryos in the female's tum-tum at a time. This gets really crowded since those babies are often more than half the length of the mother's body. Plus, when they come out they look like this:
...which is never a pleasant surprise. That's the Vengeance Team's working theory as to why caecilians are mostly blind. btw: sadness-induced self-harm. But what's even worse is what happens before they come out all wriggly and hideous (a several hour ordeal you can youtube at your own leisure). In the womb the baby caecilians use their specialized teeth to scrape away the nutrient-rich "uterine milk" that is produced in the lining of their mother's uterus. Scientists also found bits of the uterus itself in the stomachs of dissected embryos. That's right, they go for more than just milk, they literally eat part of their mother's organs.
Version B is also a terrible option, which involved reproduction through eggs. Sure, with eggs nobody's eating you from the inside out, but the commitment of the caecilian mother prevails: for a week after they hatch, the mother will cuddle her little deviant hellspawn as they periodically swarm over her and EAT HER SKIN. And we thought breastfeeding was weird.
Kupfer, A. , Muller, H. , Antoniazzi, M. , Jared, C. , Greven, H. , et al. (2006). Parental investment by skin feeding in a caecilian amphibian. Nature, 440(7086), 926-929.
Wake, Marvalee H. Fetal Maintenance and Its Evolutionary Significance in the Amphibia: Gymnophiona. Journal of Herpetology , Vol. 11, No. 4 (Oct. 31, 1977), pp. 379-386