Environment is everything which is external to the child. It could be things outside the mother. That will obviously include, father, grandparents, relatives and friends.
Sunshine, rain, air, rivers, earth and the like are also part of the environment. Clean water and pure air are good! Hence it is easy to surmise that good and clean environment is a better influence for the child.
Chemicals, hormones, enzymes are inputs coming to the child from the mother. There are also external to the child and hence part of environment. They may be good or bad – because cortisol and adrenalin seem to be created during anxiety or fear. Oxytocin is produced when there is love and appreciation!
The environmental influences are carried to the child from the mother through the physical channel or placenta/umbilical cord. But they can also reach through non-physical means. Recall, the analogy of FM Channels, mobile phones and TV. In the course of our lives we are exposed to mobile waves, radiations from video/photo cameras, X Ray / MRI / CT scans and many other such gadgets. Magnetism and Gravity are certainly known influences. These are subtle energies which are capable of reaching the child. All these constitute environmental influences.
The environment hence an important role in the pregnancy period.