The major organs systems have started developing.
It fine to travel in the first, second and third trimester.
No, normally there is minimal weight gain during the first trimester, most of the pregnancy weight gain occurs during the second trimester.
the organs grow larger
Some people gain no weight during the first trimester, particularly if they have morning sickness. Other people gain a small amount, particularly towards the end of the first trimester. The most weight is gained during the second trimester though.
The first trimester is most critical for the development of a baby. The babies brain is formed during the first trimester.
The traditional designations are: During the first trimester - abortion (spontaneous abortion, if you want to avoid ambiguity) During the second trimester - miscarriage During the third trimester - stillbirth
What hormones could be implicated in failing to maintain the pregnancy during the first trimester?
yes you can
The body organs are developed and refined.
You can, however it is not usually recommended because of the increases risk of miscarriage during the first trimester. Travelling during the second trimester is more recommended because of the much lower risk of miscarriage.