Just from personal experience it seems a fetus in more active when the mother is at rest. It's as if activity is putting the baby to sleep, which is why it is so fun to put your belly into someones back while your sleeping than the baby can keep both you and your partner awake.
Cytomegalovirus (CMV) is the most common infection that can be transmitted to a fetus.
Mother Teresa was most active in the Indian city of Calcutta.
Antibodies in the maternal blood prevent most infections from being transmitted to the fetus.
Very few infected people have symptoms and most pregnant women have antibodies that protect the fetus from infection.
Most likely there is something wrong with the fetus and it's mother nature's way discarding the fetus before you get too far into your pregnancy.
If you die when you are pregnant, an attempt will be made to save the live of the fetus, but, most of the time when the mother carrying the fetus dies, the baby inside of her dies as well.
A baby's weight can sometimes be low because of the age of the mother. All babies grow at different intervals. Most babies will grow the most during the fifth month.
Some fetus' need to be removed, but most will come out (if before 12 weeks) usually after 12 weeks it will be removed, it is very dangerous that the fetus is still in the mother, this can cause blood poisoning which can lead to death of the mother if not treated fast. Although, in rare cases fetuses have been known to remain for years and even decades.
Spraying pesticide in the garden
Any substance that the mother consumes is going to wind up in her blood stream, and it will pass through the placenta to the fetus. The development of the fetus is at its most sensitive during the first trimester, and toxic substances such as alcohol can cause abnormalities.
The fate of most fetus is to be born and become humans, or other life forms that start out as a fetus.
That there is something wrong with the fetus, it is not viable. It's mother Nature's way to deal with it.