Once you've tightly tied your mechanics to the available generic mechanics, you could probably consolidate all your feats into 3-5 uber-Feats that gave whoever took them broad and powerful advantages in particular areas - chance of survival, fertility and fecundity, health of the child, midwifery ect. These feats should be specific, but in their specific area much more powerful than feats like Skill Focus or Great Fortitude or Endurance. As a suggestion, take feats that cover three related areas and combine them into single feats offering three advantages similar in design to the 'Tactical' feats seen in some late 3.5 design. You could then make these feats 'Traits', which would then compete for attention with all the other traits in your game. They might likely be still mostly 'NPC traits', but they'd at least then be clearly desirable traits you could imagine NPC's 'taking' or prizing. Indeed, they might become a trait the PC might prize in an NPC spouse, or in an NPC retainer (in the case of 'midwifery' and dynastic campaigns). If your campaign goes truly dynastic, where children are as important or more important than having cool magic items and each player is effectively playing a household rather than a character, then those NPC traits might start moving into PC traits.
Your move to make feats extra traits that a person has someone alleviates this problem, but doesn't really deal with the main issue in the feats design - pregnancy is something that occurs only every few years at most and is only one sort of specific challenge. Not only must the campaign now feature dynastic play to make it interesting, it must go on for much longer than most campaigns actually cover. Rarely do you actually have campaigns that cover even 9 months of in game time.
Thanks for your review.
...avoid mentioning scientific concepts like DNA. It's not clear that DNA exists in a typical fantasy setting, where science...
Sooner or later, you are going to get a cease and desist from multiple authors. Consider revising your artwork, and removing trademarked designs.
Consider changing your percentage chances to chances in D20. Consider changing your fertility rules to be based off Fortitude saves. In general, I find your chance of conception rules to be vastly overcomplicated. You want one simple mechanic and maybe one easy to read table.
Why in the world does the chance of bringing a baby healthy to term have nothing to do with the Constitution of the mother?
Why go into such detail about that sort of thing, and not consider whether spells, diseases, poisons, damage and hardship that target the mother effect the child and to what degree?...
In short, you've spent a lot of time thinking about something that isn't particularly hard to rule on (does someone become pregnant?) because that event is pretty binary pass/fail sort of stuff. But the stuff that would require a lot of thought and attention to detail... doesn't show up in the rules.
Back on the subject of 'traits', it might be interesting to see feats related to having some unusual heritage, but not enough to count as 'half' mechanically.
In short, there is a lot of interesting territory you aren't covering that might make your text more interesting to more readers and be more useful to you in future play. You don't even really cover enough details to be a true 'Birth Guide' for a fantasy role playing game, but where you need to be heading is less of a 'Birds and Bees' guide for D&D that explains what happens when creatures have sex, and more to being a true dynasty guide that deals with how the fantastic elements of the game intersect pregnancy and heirs.
It is not explicit, but it is very likely that exist. The fact that a human and an elf generate a half-elf makes me belive that genetics is real in D&D.
I did not expect that someone would find my mechanics complicated.
But consider that the intention was to be realistic.
In fact i already had a more complete content about it, however i was not sure about my knowledge. I decided to make a simplefied verson, and latter make a full version. I am studying about it. I hope in a few days i already bid more details about the baby health.
Could you elaborate more about it?
The idea of this book was about pure biology, however i think to add more role play elements, such how the races react towards the act of birth.
What do you suggest to make this book more interesting?

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.