I used a pregnancy-by-week website that indicated the developmental stages of the foetus and ate according to the different growth stages. For example, if the baby was developing brain and neural synapses, I would eat high cholesterol foods. Another week it would be bones, so high levels of Vitamin D and calcium. For tissue and skin, I ate lots of fatty fish and animal fat. The nurses and doctors said that my kid was strong and hardy like a bull, so I guess it worked.
Having a child relatively late in life has its benefits — I am more confident when it comes to fighting off unsolicited advice from strongly opinionated mothers regarding ridiculous pregnancy diet taboos.
Also, being a scientist (in my previous life) armed me with the ability to regard or disregard taboos based on biochemistry and biology. It is quite alright to eat raw food and unpasteurised cheeses, provided you are acquiring it from respectable and reliable sources — the Japanese and French have been doing this since time immemorial. Also, do not kid yourself that you need to 'eat for two' during your first trimester. You are eating for yourself and a bunch of cells the size of a walnut.