I had the same problem with you during my first 7 month pregnancy. I have consulted with doctor but he said I can do nothing about it as medicine for preventing dropping hair is not good for baby. He said it's also the normal problem of pregnant women.
However, the situation suddenly turns good in my last 2 month of pregnancy. I think it's no need to become 禿頭媽媽 as it's only a temporary problem for pregnant moms.