That's still pretty broad... Are you focusing on a specific developmental theorist? I actually just did an assignment on developmental theories yesterday. Here's a few good names to keep in mind or research for that subject, and a little background:
Freud - psychoanalyst, broke development down into psycho***ual stages. Unsuccessfully completing any stage would result in a "fixation" later in life. The stages are: oral (early infancy), anal (toddlerhood), phallic (early childhood), latency (childhood until puberty), and genital (puberty and on). He also developed the theory of id, ego, and superego, which are all parts of the human mind/personality. The id is concerned with self-satisfaction and basic needs. Ego is the reality section, realizing and understanding that other people have needs as well. Superego is the morality portion... more or less the conscience.
Maslow - humanistic, he developed the hierarchy of needs. You can not move on to the second stage of needs until the first is met, can't move to the third until the second is met, etc. Stages: physiological (eating, sleeping, etc.); safety (financial security, safe home); love and belonging (family and friends); esteem (recognizing your achievements, confidence); and finally self-actualization (morality, pursuing your own interests). That's the simple hierarchy, there are additional needs after that, but I've never studied them, and they aren't included in all models.
Piaget - has a cognitive developmental theory. It had 4 stages, the first is sensorimotor (0 - 2 yrs), which is broken down into 6 substages. This is when the infant uses his senses to learn about the world around him and gain a sense of self. Pre-operational (2 - 7yrs) comes next, where the child develops language. The child also has an egocentric view of the world and trouble empathizing with others. Concrete operational (7 - 11 yrs) is when the child begins thinking logically, understands object conservation, and can follow multi-step directions. Formal operation (11+) is when children can handle abstract thinking, thinking about the future, etc. Look at this with the
stages of play and you can see how it applies to social and emotional development.
Erikson - he broke development down into 8 stages. Each stage consists of a basic conflict which must be resolved, and when it is, the person learns a "virtue" and moves on to the next conflict. This site gives a really good, quick description of his stages:
http://www.learningplaceonline.com/s...ze/Erikson.htm
There are plenty of others out there, but these 3 are my favorites and the ones I have learned most about. As far as pre-natal, studying the socio-emotional development is relatively new, and obviously more difficult since fetuses can't be observed the same way. You might have trouble finding a ton of reliable info... If you have time, I really recommend the movie In the Womb, it gives great information and is very well done.
Hope that helps!