Thank you sooo much for your very thoughtful response. I am very excited that you have taken the time to think about all of the possibilities in which these options would have holes in the plot. It forces me to make it make sense. Let me further elaborate…
Option One: Drowning in the pool: The family lives in a private Estate/ large family home. There are no life guards on duty . The father is at work and the two other children are in kinder/ primary school. The mother is at home with her youngest child ( who has not been diagnosed yet… but he exhibits characteristics that fall under the spectrum of Autism / Aspergers. Although the family has the financial wherewithal to pay for nannies and additional people to tend to the children… the mother was adamant in being the only person to rear all of her children. The mother is experiencing a particularly bad migraine headache and was in the course of getting ready to take a nap as her son was already sleeping. Before laying down she decides to check on her son and discovers that not only is he no longer asleep, he has managed to leave the room completely. Meanwhile, the pool man who was working on changing the filters and other pool maintenance did not have a particular part to fix an issue. So he had left to pick up the part at the hardware store. He did not secure the door to the mud room that leads to the backyard nor did he secure the safety gate to the pool. The young child ends up in the pool… the panicked mother dives in to save the child ( but her senses and perception are skewed due to migraine complications ) she is able to rescue the child but is not able to gather her equilibrium enough to save herself. The pool man returns to find the child sitting on the edge of the pool and the mother floating facedown in the pool.
Option Two: Getting hit by a car: Mother has severe migraine, child escapes because secure doors are not secured as grounds keeper left the house briefly to replace a specific tool needed for their work. Mother discovers child entering the street as car heads towards them. Mothers perception is off and gets struck by the car while pushing her child out of the way ( car was being driven over the residential speed limit , but because the front of the car struck the mothers body and head the injuries she sustained were fatal )
Option Three: Dying from complications of giving birth:
As you have pointed out ( and I greatly appreciate your perception ) the scenario is not sound and logical. So I have to nix the idea of the mother going against doctors suggestion. It just doesn’t work. And it is not something a person of sound mind would do. Mother would have to suffer from an unforeseen complication that absolutely nobody had been aware of including the doctors )